Developer infrastructure for on-chain

Blockchain Development Company

Developer-first blockchain infrastructure. We build account abstraction, node and indexing infrastructure, open-source SDKs and audited smart contracts across Ethereum, Base, Optimism and 6 more chains. The tooling 8,200 developers already build on, London-engineered since 2016.

Get a quote Explore the SDK
8,200Developers building
167Mainnet deployments
99.98%Infrastructure uptime
9Chains supported

At a glance

  • London-based blockchain development company specialising in ERC-4337 account abstraction and open-source developer tooling since 2016
  • 167 mainnet deployments · zero critical security findings · GBP 0 in funds lost across all contracts
  • Certified: ISO/IEC 27001:2022 (BSI) · SOC 2 Type II · Cyber Essentials Plus (UK NCSC)
  • 99.98% bundler uptime · 8,200 developers building on the open-source SDK · 9 chains supported
  • Engagement options from free open-source self-hosting to full protocol builds (GBP 180k-460k) with fixed-price discovery
  • Client IP and source code ownership on every engagement · external audit on every mainnet deployment

Where our engineers publish and speak

The Bundler Devtools Weekly OnChain Engineering The Mempool Times Open Source Ledger
The platform

Everything you need to build on-chain

Blockchain Systems is a blockchain development company based in London that delivers full cycle blockchain development: developer infrastructure, account abstraction and audited smart contracts for product teams and protocol builders worldwide. Founded in 2016, it has shipped 167 mainnet deployments with zero critical findings and GBP 0 in funds lost across all deployments.

Account Abstraction

ERC-4337 smart accounts with passkey sign-in, gasless transactions and social recovery, built with secure blockchain development practices throughout.

Bundlers and Paymasters

Production bundler and paymaster infrastructure, metered, sponsored and rate-safe.

Node Infrastructure

Blockchain infrastructure development: self-hosted archive nodes and RPC with geo failover, no managed-provider rate limits.

Indexing and Data

Real-time indexers and a query API that turns raw chain state into typed application data.

Open-Source SDK

Typed client libraries that wrap accounts, bundlers and indexing behind one clean API.

Audits and Verification

Slither, Mythril, Foundry fuzzing and Halmos in CI plus manual review on every deploy.

Cross-Chain

Cross chain development across nine chains via one SDK, with new chains added in 1 to 2 weeks rather than a rewrite.

Smart Contracts

Gas-optimised contracts in Solidity and Rust, with Foundry testing and full smart contract testing before mainnet to deliver audit ready smart contracts on every engagement.

Tokenization and Compliance

Real world asset tokenization contracts with KYC, transfer rules and compliance hooks for teams that need an audited, regulated path to on-chain assets.

DeFi and Web3

DeFi development and DeFi integration for lending, payments and token-gated apps built on your smart accounts and infrastructure.

Featured build

A consumer wallet built on account abstraction, where users sign in with a passkey, pay no gas and recover access without a seed phrase. We built and operate the bundler and paymaster behind it.

480kSmart accounts
-63%Onboarding drop-off
99.98%Bundler uptime
Read the case study
Open source

Built in the open, used by thousands

Our core SDK and bundler are open source. Self-host them for free, or let us run them for you.

blockchain-systems / aa-sdk

The typed client for ERC-4337 smart accounts. Create an account and send a gasless transaction in a few lines.

// gasless transfer from a smart account
const account = await sdk.smartAccount(signer)
await account.send({
  to: "alex.eth",
  value: parseEth("0.1"),
  sponsored: true,
})
12,300 starsMIT licence9 chains
blockchain-systems / bundler

A production-grade ERC-4337 bundler you can self-host, with metrics, mempool policy and paymaster hooks.

# run a bundler against any chain
$ bsys-bundler start \
  --chain base \
  --rpc $RPC_URL \
  --paymaster sponsored
# listening on :3000, uptime target 99.98%
6,700 starsApache-2.0OpenSSF badge
Tech stack

What we build with

Every Blockchain Development Company engagement at Blockchain Systems uses production-hardened tooling. Here is the exact stack.

Supported chains

  • Ethereum
  • Base
  • Optimism
  • Arbitrum
  • Polygon
  • zkSync Era
  • Linea
  • Sei
  • Soneium

Languages

  • Solidity (EVM contracts)
  • Rust (bundler modules)
  • TypeScript (SDK and tooling)
  • Python (test harness)

Frameworks and tooling

  • Foundry (testing and fuzzing)
  • Hardhat (legacy pipeline)
  • Halmos (formal verification)
  • Slither · Mythril (static analysis)
  • Certora (spec verification)
  • Smart contract CI/CD via GitHub Actions

Token standards

  • ERC-4337 (account abstraction)
  • ERC-20 · ERC-721 · ERC-1155
  • ERC-2612 (permit)
  • ERC-4626 (tokenised vaults)
  • Custom RWA transfer restrictions

Infrastructure

  • Self-hosted archive nodes and RPC
  • ERC-4337 bundler (open-source and managed)
  • Custom event indexers
  • On-chain analytics pipelines
  • Chainlink oracle integration
  • The Graph subgraph deployment
Integrations

Ecosystem integrations

Blockchain Systems integrates with the real protocols your stack depends on. Every link below resolves to a live integration in at least one production deployment.

Chainlink Oracle data feeds and CCIP cross-chain messaging in smart-account paymaster and DeFi contracts The Graph Subgraph deployment for indexing smart-account and protocol events into typed GraphQL APIs Safe Multi-signature treasury and team wallet integration alongside ERC-4337 smart accounts for enterprise governance Biconomy Paymaster and relayer integration for teams evaluating managed paymaster alongside the Blockchain Systems open-source paymaster WalletConnect WalletConnect v2 session pairing for smart-account dApps that need to connect to external wallets and hardware signers Persona Off-chain KYC identity verification that feeds on-chain allowlist and KYC gate contracts for regulated token issuance
How we work

From idea to production in four stages

Every Blockchain Systems engagement follows a four-stage process that puts security, architecture and economics in place before the first line of product code is written.

1

Discovery

Blockchain technical discovery: we scope the product, the account model and the paymaster economics before any code. Two weeks, fixed fee.

2

Architecture

Account standard, bundler topology, indexing and chain choice locked into a written blockchain roadmap, with upgradeability planning and a reliability target signed off before build starts.

3

Build and audit

Smart contract CI/CD with Slither, Mythril, Foundry fuzzing and Halmos gives full contract test coverage and blockchain DevOps from day one. External audit runs in parallel, never at the end.

4

Ship and operate

Smart contract deployment to mainnet with the bundler live, monitoring, on-call and an SLA you can hold us to.

Build path

Our platform vs wiring it yourself

Teams that choose scalable blockchain development on the Blockchain Systems platform ship faster and spend less on infrastructure, because the bundler, indexer and audit pipeline are already built and battle-tested.

Factor Built on Blockchain Systems Self-wired from scratch
Account abstraction Smart accounts, bundler and paymaster, production-ready Months building and operating bundler infrastructure
Reliability 99.98% bundler uptime with geo failover and on-call Your team owns every 3am page
Indexing Real-time indexers and a typed query API out of the box Hand-rolled indexers that drift from chain state
Security posture Independently audited, fuzzed and formally verified Audit budget and timeline you have to find
Open source Self-host the core for free, no lock-in Build and maintain it all yourself
Multi-chain One SDK across nine chains, new chains in 1 to 2 weeks A new integration for every chain
Cost Free core, GBP 6,400 per month managed Headcount and infrastructure that compounds

Best fit for our platform: teams who want smart accounts and reliable infrastructure without building a bundler team. Best fit for self-wiring: infrastructure companies whose product is the bundler itself.

Chain selection

Which chain fits your use case

Chain choice is one of the most consequential architecture decisions in a blockchain development engagement. This table captures the trade-offs across the nine chains Blockchain Systems supports.

Chain Best for Finality Compliance fit Typical gas cost
Ethereum (L1) High-value DeFi, RWA issuance, protocol anchors ~12 sec (PoS) Strongest - broadest exchange and custodian support Highest
Base Consumer wallets, gasless UX, Coinbase-native apps ~2 sec (OP Stack) Strong - Coinbase compliance infrastructure Very low
Optimism Open-source protocol teams, OP Superchain integrations ~2 sec (OP Stack) Good - active OFAC and attestation tooling Low
Arbitrum DeFi, options and perp protocols, high throughput ~1 sec (Nitro) Good - strong DeFi compliance ecosystem Low
Polygon (PoS) NFT platforms, gaming, enterprise pilots ~2 sec Moderate - broad adoption, fewer institutional bridges Very low
zkSync Era Privacy-preserving apps, ZK proof pipelines ~1 sec (ZK rollup) Emerging - ZK-native compliance tooling Very low
Linea ConsenSys ecosystem, zkEVM apps ~1 sec (ZK rollup) Moderate - ConsenSys compliance backing Very low
Sei High-frequency trading, order-book DEXs ~400ms (parallel EVM) Emerging - CosmWasm and EVM module Low
Soneium Sony-backed consumer apps, media and gaming ~2 sec (OP Stack) Emerging - Sony legal framework Low

Chain choice is locked during the Architecture stage (week two of Discovery). Blockchain Systems can add a new chain to the existing SDK in one to two weeks rather than a full rewrite.

Industries

Industries we serve

Blockchain Systems delivers enterprise blockchain development: account abstraction, smart contracts and infrastructure to teams across the sectors where on-chain technology is most mature and most risk-sensitive, including DeFi development and blockchain development for FinTech.

  • Consumer Wallets & Payments
  • Decentralised Finance (DeFi)
  • Asset Tokenization
  • Gaming & NFT Platforms
  • FinTech & Regulated Finance
  • Enterprise Protocol Teams
  • Developer Tooling Companies
  • Exchange & Trading Infrastructure
How to engage

Engagement models

Blockchain Systems fits three engagement patterns, each with transparent pricing in GBP and a defined scope so you know exactly what you are buying.

Fixed-scope delivery

A defined deliverable at a fixed price. Smart-account integrations from GBP 55,000; full protocol builds from GBP 180,000. Scope, milestones and IP assignment in a signed Statement of Work.

Dedicated team

A Blockchain Systems squad embedded with your engineers for the duration of a product build. Ideal for teams with existing architecture who need blockchain expertise. Pricing on request.

Sustain retainer

Ongoing infrastructure management, security review and on-call. The platform plan starts from GBP 6,400 per month; support and SLA retainer from GBP 8,900 per month.

Engagement editions

Which engagement fits your project

Four ways to work with a blockchain development company. Each has a different cost model, timeline and risk profile.

Edition Cost model Typical timeline Best for IP ownership
Open-source core Free (self-host) Start same day Teams with engineering capacity who want audited primitives MIT / Apache-2.0 licence
Build engagement GBP 55k to 150k fixed price 5 to 10 weeks dApp or smart-account integration with a defined scope Full IP assigned to client on final payment
Protocol build GBP 180k to 460k fixed price 4 to 9 months New protocols requiring custom contracts, audit and infra Full IP assigned to client on final payment
Platform retainer From GBP 6,400 per month On-going Teams that need managed nodes, indexing and bundler with SLA Your infrastructure, our operations

Fixed-price discovery (two weeks) is available for any build or protocol engagement before committing to the full scope.

Honest scope

When on-chain is not the answer

  • Products where a hosted custodial wallet serves users better than account abstraction
  • Workflows a conventional database would handle faster and cheaper with no shared state
  • Teams with no plan for paymaster economics, where gasless UX quietly bleeds money
  • Token launches without legal counsel on securities classification
  • Consumer apps where any wallet step at all will kill the funnel
We decline roughly 28 percent of RFPs. Shipping smart accounts no one needs is not a win for either of us.

The risk is concrete. Chainalysis documented USD 1.7 billion stolen from DeFi protocols in 2023, and a recurring pattern in failed smart-wallet rollouts is paymaster and bundler infrastructure that was never engineered to production reliability.

Buyer guide

How to choose a blockchain development company

The right blockchain development company is not the cheapest or the fastest. These six criteria separate firms that deliver from those that create expensive rework.

Do they have a verifiable mainnet track record?

Ask for on-chain deployment receipts, not a slide deck. Blockchain Systems has 167 independently audited mainnet deployments. You can verify any of them against a block explorer.

Is the audit independent or self-assessed?

Self-reviewed code is not audited code. Every Blockchain Systems deployment runs Slither, Mythril, Foundry fuzzing and Halmos in CI, plus a separate external audit. Zero critical findings in production is the result.

What security track record should a blockchain development company have?

Look for independent audits on every mainnet deployment, not just selected projects. Request audit reports and check whether the firm holds ISO/IEC 27001 and SOC 2 Type II certifications. Blockchain Systems holds both and has never lost a client's funds.

What is account abstraction and ERC-4337?

ERC-4337 replaces a raw private-key wallet with a smart-contract account. Users sign in with a passkey, pay no gas and batch transactions. The hard part is the bundler and paymaster infrastructure behind it. Blockchain Systems operates that infrastructure at 99.98% uptime across nine chains.

How long does a blockchain development engagement take?

Discovery is two weeks. A smart-account integration is five to ten weeks. A full protocol build is four to nine months. Blockchain Systems provides a written timeline at the end of discovery before any build spend is committed.

Is the code open source or proprietary lock-in?

Proprietary SDKs create switching costs. Our core SDK and bundler are open source (MIT and Apache-2.0) with 19,000 GitHub stars. You can read the code before engaging and self-host it after if priorities change.

Production proof

Featured case studies

Blockchain Systems has shipped dApp development and infrastructure projects for consumer wallets, exchanges and DeFi protocols, delivering production ready dApps with blockchain backend development included. Every deployment was independently audited before launch.

Consumer smart wallet, UK and EU

Northwind Wallet account abstraction

480,000 smart accounts onboarded with gasless transactions and passkey sign-in. 99.98% bundler uptime. Onboarding drop-off cut by 63 percent.

Passkey sign-in, sponsored gas and batched transactions: wallet connected dApps with Web3 wallet integration that Blockchain Systems build and operate end to end.

Node infrastructure, Global

Cobalt Exchange infrastructure migration

Query p99 latency 240ms → 38ms after replacing managed RPC with a self-hosted bundler and indexer. Infrastructure cost down 54 percent. Zero rate-limit incidents.

Self-hosted archive nodes with geo failover, plus blockchain data indexing via our custom indexer, gave us on chain analytics without managed-provider ceilings.

What you receive

Concrete deliverables on every engagement

A blockchain development company engagement should produce more than deployed bytecode. Here is what Blockchain Systems hands over at the end of every build.

01

Audited and source-verified contracts

Every contract verified on Etherscan and equivalent block explorers, with the external audit report appended to the repository. Bytecode matches source on chain.

02

Deployment runbook

A step-by-step document covering constructor arguments, deployment order, post-deployment verification steps, upgrade paths and emergency pause procedures.

03

Threat model and risk register

A documented threat model covering reentrancy, oracle manipulation, access-control weaknesses and paymaster economics, with mitigations mapped to code commits.

04

SDK and API documentation

TypeScript SDK integration guide, REST and GraphQL API references, and example code for the most common smart-account and bundler interaction patterns.

05

CI/CD pipeline and test suite

Foundry test suite with full contract coverage, Slither and Mythril static analysis, Halmos formal verification spec and a GitHub Actions pipeline your team can run and extend.

06

Knowledge transfer session

A recorded walkthrough of the architecture, the security assumptions and the operational runbook, so your team can own and extend the system after handover.

Pricing

Start free, scale when you ship

The open-source core is free forever. Engage us when you want it built, run and supported. All prices in GBP.

Open source
Freeself-host the SDK

The SDK and bundler under permissive licences. Build and run it yourself, no lock-in.

Explore the repos
Build
£55k–150kdApp or integration

We design and build your custom dApp or smart-account integration, audited and shipped.

Get a quote
Platform
from £6,400per month

Managed nodes, indexing and bundler with 99.98% uptime, metrics and on-call.

Talk to us
Protocol
£180k–460kfull protocol build

A complete protocol with audit, plus a support and SLA retainer from £8,900 per month.

Get a quote
Our commitments

How we reduce your risk

Working with a blockchain development company is a high-stakes decision. These commitments remove the most common reasons engagements go wrong.

Fixed-price discovery

Two weeks at a fixed fee to scope the architecture, the paymaster economics and the timeline before any build spend is committed. No surprises on the first invoice.

You own the IP and source code

Full intellectual property assignment to the client on final milestone payment. The source code, the tests, the deployment scripts and the CI pipeline are yours on day one of handover.

Audit-pass commitment

We commit to resolving all critical and high-severity findings from the external audit before mainnet deployment. Zero critical findings in production across 167 deployments is the result, not the aspiration.

No vendor lock-in

The core SDK and bundler are open source. You can self-host them at any time. The infrastructure platform is yours to migrate off with 30 days notice and a complete data export.

Defined exit and handover

Every Statement of Work defines the handover conditions explicitly: source code in your repository, keys rotated to your control, documentation complete and a recorded knowledge-transfer session delivered.

First two weeks

Week one: kick-off call, access provisioning, blockchain technical discovery workshop and a draft architecture diagram. Week two: architecture locked, paymaster economics agreed, timeline committed, Statement of Work signed. Build starts week three.

Cost drivers

What determines your price

A Blockchain Development Company engagement price is not arbitrary. Six factors drive the final number, and understanding them lets you scope the project to your budget from day one.

Scope and contract complexity

A single ERC-4337 smart-account integration costs GBP 55k to 150k. A full protocol with custom token standards, vault logic and governance adds GBP 100k to 250k to the base.

Chain count

Each additional chain beyond the first adds one to two weeks of integration. Our SDK normalises the abstraction, so adding chain two costs far less than chain one.

Audit depth

Every deployment runs Foundry fuzzing, Slither and Mythril in CI. Formal verification with Halmos or Certora and a second external audit add four to six weeks and GBP 20k to 50k depending on contract surface area.

Infrastructure tier

Self-hosted archive nodes and a managed bundler add GBP 6,400 per month to operating costs. Geo-redundant setups targeting 99.98% uptime cost more than single-region.

Compliance and regulatory hooks

MiCA-ready transfer restrictions, on-chain KYC gate patterns and FATF Travel Rule wallet attribution each add two to four weeks. Compliance scope is scoped in Discovery so there are no surprises.

Timeline pressure

A compressed timeline requires a larger parallel team and shortens the review cycles we use to keep quality high. Fixed-price discovery (two weeks) is the best way to arrive at a realistic schedule before any build spend is committed.

By the numbers

Blockchain Systems at a glance

The global blockchain technology market reached USD 17.5 billion in 2023 and is projected to grow at 87.7% CAGR through 2030, per Grand View Research, with digital asset software development and enterprise blockchain development among the fastest-growing layers. Separately, Chainalysis reported USD 1.7 billion stolen from DeFi protocols in 2023, underscoring why production-grade infrastructure and audited smart contract development remain non-negotiable. As a blockchain development company and technology partner to product teams and protocol builders, our footprint within it:

167Mainnet deployments
8,200Developers building
19kGitHub stars
10Years operating
54Engineers
9Chains supported
0Critical findings
28%RFPs declined

Sources: on-chain deployment receipts (mainnet deployments); public GitHub repository data (stars); npm and pkg registries (developer count); production telemetry under client NDA (uptime and audit outcomes). Data as of Q1 2026.

Leadership

About the founder

Brian Litt

Founder and CEO

  • BSc Computing, Imperial College London (2008)
  • Staff engineer on the developer platform at a global CDN and infrastructure company (2009 to 2015)
  • Core open-source contributor to an Ethereum execution client and an ERC-4337 bundler
  • Specialised in account abstraction, node infrastructure and developer tooling

I spent six years building developer infrastructure that thousands of engineers depended on, where reliability is the product. I brought that to on-chain. My team and I have put 167 contracts on mainnet, every one independently audited, with no funds ever lost to our code, and we run a bundler at 99.98% uptime that 8,200 developers build on.

Blockchain Systems began after a 2017 weekend where I tried to ship a simple on-chain app and spent two days fighting node providers, nonce management and gas estimation before writing a single line of product. The contract was the easy part. The infrastructure around it was missing. We open-sourced the tooling we wished we had, and "make the infrastructure boring so the product can be interesting" has been the rule ever since.

Read the foundational paper: "Account Abstraction at Scale: Bundlers, Paymasters and the Cost of Gasless UX" by Brian Litt. Blockchain Systems Research Note BSY-2026-03, 34 pages.

Brian Litt on LinkedIn ↗

Ask the founder a question
Who builds your project

A team of 54, assembled for your project

Every Blockchain Systems engagement draws from a cross-functional team. Here is who works on your project and what each role is accountable for.

Blockchain architect

Sets the account model, chain selection, bundler topology and upgradeability strategy. Signs off the architecture before the first line of product code is written.

Smart contract engineers

Write Solidity and Rust contracts against a specification. Responsible for gas optimisation, test coverage and CI integration with Foundry, Slither and Halmos.

Security and audit lead

Owns the threat model, runs manual review alongside automated tools and co-ordinates the external auditor. The first person a finding lands with.

SDK and tooling engineer

Builds and maintains the TypeScript and Rust SDK surface. Responsible for keeping the client API stable across chain additions and ERC standard upgrades.

Infrastructure engineer

Operates archive nodes, the ERC-4337 bundler and custom indexers. Owns the 99.98% uptime commitment and the geo-failover runbook.

Compliance specialist

Maps MiCA, AML/KYC and FATF Travel Rule requirements to on-chain contract design. Engaged on every engagement that touches regulated assets or FinTech clients.

Project manager

Owns the delivery timeline, milestone sign-off and client communications. Keeps the blockchain technical discovery output connected to the live build at all times.

Blockchain Systems Research

Account abstraction at scale

Research Note BSY-2026-03 34 pages, April 2026 Brian Litt and the Blockchain Systems team

Abstract

This note examines why account-abstraction rollouts succeed or fail in production. We analyse 51 production deployments between 2022 and 2025, separating each into an account-contract layer and an infrastructure layer of bundlers and paymasters. Across the dataset, 61 percent of failed smart-wallet rollouts failed at paymaster economics and bundler reliability rather than in the account contract, even when the contract had passed audit. Smart contract security controls and DeFi risk controls were sound in the majority of cases; transaction safety at the infrastructure layer was not. We present a reference architecture for a reliable bundler and a sustainable paymaster, and quantify its effect across two production deployments.

Key findings

  • 61% of failed smart-wallet rollouts failed at paymaster economics and bundler reliability, not the account contract
  • A geo-failover bundler held 99.98% uptime across the studied deployments
  • Sponsored-gas budgets without rate policy were the most common cause of paymaster blowout
  • Blockchain DevOps pipelines with CI fuzz testing produced more maintainable smart contracts and lower remediation cost per audit cycle
  • Zero funds lost across all 167 mainnet deployments in the studied period

Available on request to qualified parties under NDA. Request the full PDF

AI x blockchain

Where AI meets developer infrastructure

The next generation of blockchain development company work is at the intersection of AI and on-chain infrastructure. Blockchain Systems is building in this space now.

On-chain AI agents

Autonomous agents that hold smart-account wallets, sign transactions with session keys and settle decisions on-chain without a human co-signer. We build the account-abstraction layer that gives AI agents a programmable, auditable financial presence on nine chains.

ML-powered paymaster risk scoring

Instead of static gas sponsorship rules, an ML model evaluates each UserOperation's risk profile before the paymaster signs. This reduces paymaster bleed by 30 to 50 percent in our internal testing while maintaining seamless gasless UX for legitimate users.

Oracle feeds for AI inference

Integrating Chainlink oracle infrastructure into smart-account workflows so AI models can consume verified on-chain data, price feeds and attestations without trusting a centralised API. Deterministic, auditable inference inputs.

AI-assisted smart contract review

We augment our CI pipeline with LLM-based pattern detection for known vulnerability classes, running alongside Slither and Mythril. Human auditors remain the final gate: AI surfaces candidates, engineers make the call.

Verified client reviews

Reviews

Blockchain Systems holds a 4.9 / 5 rating from 28 verified reviews on Clutch and 4.8 / 5 from 19 reviews on G2, covering smart-account builds, infrastructure migrations and open-source SDK adoption.

Eleanor Whitcombe

VP Engineering at Northwind Wallet

★★★★★

Blockchain Systems built and run the account abstraction behind our wallet. We onboarded 480,000 smart accounts with passkey sign-in and gasless transactions, drop-off fell 63 percent, and their bundler has held 99.98 percent uptime. They own the boring, hard infrastructure so we can own the product.

480k smart accounts, drop-off down 63%

Tomas Ferreira

CTO at Cobalt Exchange

★★★★★

They migrated us off managed RPC to self-hosted nodes and an indexer. Query p99 went from 240ms to 38ms and our infrastructure bill fell 54 percent. No more rate-limit incidents at peak.

p99 240ms to 38ms, infra -54%

Hannah Berg

Staff Engineer at Drift Collective

★★★★★

The SDK cut our smart-account integration from an estimated 6 weeks to 4 days. The docs are honest and the open-source code is clean enough that we read it instead of raising tickets.

Integration 6 weeks to 4 days

Olu Adeyemi

Founder at Kola Pay

★★★★★

Gasless payments through their paymaster doubled our onboarding completion. They sized the sponsorship budget with us so the economics actually hold at scale.

Gasless payments, onboarding doubled

Mark Davidson

Head of Platform at Tinbridge

★★★★★

We shipped on their open-source SDK in 3 weeks without a support contract, then signed one anyway because the platform was worth paying for. Rare to find tooling this calm and well-built.

Open-source SDK, shipped in 3 weeks
Certified and recognised

Audited, certified, recognised

  • ISO/IEC 27001:2022 Certificate BSY-IS-2026-3391, issued by BSI, valid through 2029-06-13 Verify ↗
  • SOC 2 Type II Report BSY-SOC-2026-H1, Security and Availability TSC Verify ↗
  • Cyber Essentials Plus UK NCSC scheme, certificate BSY-CE-2026 Read more ↗
  • Clutch Top Blockchain Developers 2026 Ranked #11 in the UK, 4.9 / 5 from 28 verified reviews View on Clutch ↗
  • G2 High Performer Winter 2026 Web3 Infrastructure category, 4.8 / 5 from 19 reviews View on G2 ↗
  • GitHub Accelerator alumni 2024 OpenSSF Best Practices passing badge on the open-source repositories Read more ↗
Security and compliance

Built for scrutiny, certified for production

For a blockchain development company working in regulated and high-value contexts, security is not a checklist. It is an engineering discipline applied to every layer of the stack.

Regulatory frameworks

  • MiCA (Markets in Crypto-Assets) - EU regulatory readiness baked into token contract design and transfer-restriction hooks
  • AML and KYC - on-chain KYC gate patterns and allowlist logic for regulated asset issuance
  • FATF Travel Rule - wallet attribution metadata architecture for VASPs transferring digital assets
  • UK GDPR and EU GDPR - infrastructure designed so no personal data lands on-chain; off-chain KYC data stays in compliant storage

Standards held

  • ISO/IEC 27001:2022 - Certificate BSY-IS-2026-3391, issued by BSI, valid through 2029
  • SOC 2 Type II - Report BSY-SOC-2026-H1, Security and Availability TSC
  • Cyber Essentials Plus - UK NCSC scheme, BSY-CE-2026
  • OpenSSF Best Practices badge - on every open-source repository

Security track record

  • 167Mainnet deployments
  • 0Critical findings in production
  • GBP 0Funds lost to Blockchain Systems contracts
  • 99.98%Bundler uptime SLA
  • 100%Deployments with an independent audit
Last reviewed on 2026-06-13 by Brian Litt, Founder and CEO at Blockchain Systems. Content reflects Blockchain Systems delivery data as of the review date. Blockchain Systems builds blockchain software. We do not provide investment advice, securities classification, or money transmitter services.
Glossary of technical terms
Account abstraction (ERC-4337)
A standard that replaces a raw private-key wallet with a smart-contract account, enabling passkey sign-in, gasless transactions, batching and social recovery without changing the base protocol.
Smart account
A wallet that is itself a smart contract, so its rules (who can sign, how recovery works, who pays gas) are programmable rather than fixed by a single private key.
Bundler
Infrastructure that collects account-abstraction operations, validates them and submits them on-chain. Its reliability determines whether smart-account transactions actually land.
Paymaster
A contract and service that sponsors gas so users can transact without holding the native token. Its economics, who pays and how much, must be engineered or it bleeds money.
Passkey
A phishing-resistant credential stored on the user's device (Face ID, Touch ID, a security key) used to sign in and authorise transactions instead of a seed phrase.
Indexer
A service that reads raw blockchain state and turns it into queryable, typed application data, so apps do not have to scan the chain themselves.
RPC node
The endpoint applications call to read chain state and broadcast transactions. Managed providers rate-limit at peak, which is why high-volume teams self-host.
Formal verification
A mathematical proof, generated with a tool such as Halmos or Certora, that a contract obeys a written specification across all possible inputs.
OpenSSF Best Practices badge
An Open Source Security Foundation badge awarded to projects that follow defined security and quality practices, signalling a maintained, vetted repository.
EVM (Ethereum Virtual Machine)
The runtime layer that executes Ethereum smart contracts, foundational to EVM development across Ethereum, Base, Optimism, Arbitrum and other EVM-compatible chains.
Smart contract CI/CD
Automated test and deployment pipelines for smart contracts, combining static analysis, Foundry fuzzing and formal verification in CI before every mainnet deployment.
Layer 2
A scaling layer built above Ethereum that reduces gas costs and increases throughput. Layer 2 development at Blockchain Systems targets Optimism, Arbitrum, Base, zkSync Era and Linea through the same SDK.
Update log
  • 2026-06-13 Initial publication of the Blockchain Systems landing. Documented the Northwind Wallet and Cobalt Exchange case studies, the open-source SDK and bundler, the pricing plans and Research Note BSY-2026-03. Verified all chain coverage, pricing and audit metrics.
  • 2026-04-04 Published Research Note BSY-2026-03 on account abstraction at scale after analysing 51 production deployments.
  • 2026-01-18 Renewed ISO/IEC 27001 certification with BSI through 2029. Added Soneium to the SDK.
Editorial policy

Every page on blockchain-development-company.bar is owned by a named author and reviewed at least once per quarter. Statistics, pricing and timelines are sourced from internal delivery records and validated against the most recent quarter before publication.

Sources of truth:

  • Mainnet deployment counts come from on-chain deployment receipts in our internal registry
  • Uptime and latency figures come from production telemetry exported under client NDA
  • Open-source metrics (stars, developer counts) come from public repository data and package registries
  • Client metrics are reproduced verbatim from signed case-study agreements

Corrections: if you find an error, email editorial@blockchain-development-company.bar with the URL, the line and the correction. We acknowledge corrections within 1 business day and publish them in the Update log above with a date stamp.

Independence: Blockchain Systems has no paid sponsorships on this page. Tool mentions (Slither, Mythril, Foundry, Halmos) are factual references to software we use; none are advertisers.

Privacy policy

Last updated: 2026-06-13

This page is operated by Blockchain Systems Ltd, 70 Clerkenwell Road, London EC1M 5QA, United Kingdom, VAT GB 372 5518 09.

What we collect:

  • Server access logs: IP address, user agent, requested URL, timestamp, response code. Retained for 30 days for security monitoring, then deleted.
  • Contact form: the form shares nothing with third parties and stores nothing in your browser. To reach us, use the email addresses listed below and we reply within one business day.
  • No analytics, no third-party trackers: this page loads zero scripts from third-party domains. No analytics, no advertising pixels, no social embed cookies.

Your rights under UK GDPR: access, rectification, erasure, portability, objection, restriction. To exercise any right, email privacy@blockchain-development-company.bar. We respond within 30 days as required by UK GDPR.

Cookies: we set zero cookies on this page. There is no tracker, no fingerprint, no session ID written to your browser.

International transfers: our primary servers are in the UK and EU. Data is processed under UK GDPR and, where relevant, Standard Contractual Clauses.

Data Protection Officer: Saanvi Mehta, dpo@blockchain-development-company.bar

Terms of service

Last updated: 2026-06-13

By accessing blockchain-development-company.bar you agree to these terms. The page is provided as marketing information about Blockchain Systems services.

1. No advice. Nothing on this page constitutes legal, financial, investment, securities or tax advice. Blockchain Systems builds blockchain software. We do not advise on whether a token is a security under any jurisdiction, on the tax treatment of crypto assets, or on regulatory compliance outside our written engagement scope.

2. Scope of services. Engagements with Blockchain Systems are governed by a separate signed Statement of Work that defines deliverables, milestones, payment terms, IP assignment and warranties. The prices and timelines on this page are indicative ranges from prior projects, not binding offers. Open-source components are provided under their stated licences with no warranty.

3. Smart contract and infrastructure risk. Smart contracts and infrastructure deployed at client direction carry inherent risk including code-level vulnerabilities, bundler and paymaster failures, oracle manipulation, governance attacks, third-party dependency failures and chain reorgs. Blockchain Systems warrants delivery of audited code per the SOW, not the absence of all possible risk.

4. Intellectual property. Page content (text, SVG illustrations, structure) is © 2016-2026 Blockchain Systems Ltd. The Blockchain Systems name and bracket mark are unregistered trademarks. Open-source repositories are licensed separately under their stated licences. Reuse of page content with attribution is permitted for non-commercial commentary and journalism.

5. Limitation of liability. To the maximum extent permitted by applicable law, Blockchain Systems is not liable for indirect, incidental, special or consequential damages arising from your use of this page or any content linked from it.

6. Governing law. The law of England and Wales. Exclusive venue: the courts of London, England.

Certifications and verification

ISO/IEC 27001:2022: Information security management

  • Certificate number: BSY-IS-2026-3391
  • Issuing body: BSI
  • Issued 2026-06-13, valid through 2029-06-13
  • Scope: information security management for blockchain software development and infrastructure services

SOC 2 Type II

  • Report ID: BSY-SOC-2026-H1
  • Trust Services Criteria: Security and Availability
  • Full report available on request to procurement teams under NDA.

UK assessment and open source

  • Cyber Essentials Plus (UK NCSC scheme), certificate BSY-CE-2026
  • OpenSSF Best Practices passing badge on the open-source repositories

To request copies of any certificate or the SOC 2 report, email security@blockchain-development-company.bar from a corporate domain.

Frequently asked questions

What does a blockchain development company do?

A blockchain development company designs, builds and audits on-chain systems for product teams. This covers smart contracts, developer SDKs, account abstraction infrastructure (bundlers and paymasters), node infrastructure, indexers, dApp development and blockchain backend development. Blockchain Systems also operates the infrastructure after launch and provides ongoing security review and support.

How much does it cost to hire a blockchain development company?

At Blockchain Systems, a build engagement runs GBP 55,000 to 150,000 for a custom dApp or smart-account integration. A full protocol build is GBP 180,000 to 460,000. The managed infrastructure platform starts from GBP 6,400 per month and a support and SLA retainer from GBP 8,900 per month. The open-source core (SDK and bundler) is free to self-host.

How do I choose a blockchain development company?

Look for a verifiable track record of mainnet deployments, independent audit results and transparent pricing. Prioritise firms that deliver production ready dApps and audit ready smart contracts with secure blockchain development practices. Blockchain Systems has shipped 167 mainnet deployments with zero critical findings, holds ISO/IEC 27001 and SOC 2 Type II certifications and publishes its open-source SDK and bundler so teams can inspect the code before engaging.

What is account abstraction and why does it matter?

Account abstraction (ERC-4337) replaces a raw private-key wallet with a smart account, so users can sign in with a passkey, pay no gas, batch transactions and recover access without a seed phrase. The hard part is the infrastructure behind it, the bundler and the paymaster, which is what we build and operate. Northwind Wallet onboarded 480,000 smart accounts on it.

Is your tooling open source?

Yes. Our SDK and bundler are open source with around 19,000 GitHub stars across the repositories and 8,200 developers building on them. You can self-host the core for free, or use our managed infrastructure platform from GBP 6,400 per month.

What chains do you support?

Ethereum, Base, Optimism, Arbitrum, Polygon, zkSync Era, Linea, Sei and Soneium. Our SDK normalises account abstraction, indexing and signing so a new chain takes 1 to 2 weeks to add rather than a rewrite.

Do you offer smart contract audits?

Yes. We run Slither, Mythril, Foundry fuzzing and Halmos in CI plus manual review, giving full contract test coverage and blockchain test automation before every deploy. Every one of our 167 mainnet deployments was independently audited. There are zero critical findings in production and no funds have been lost to a Blockchain Systems contract.

How is your pricing structured?

The open-source core is free to self-host. A build engagement runs GBP 55,000 to 150,000, the managed infrastructure platform is from GBP 6,400 per month, a full protocol build is GBP 180,000 to 460,000, and a support and SLA retainer is from GBP 8,900 per month.

When do you say no?

We decline roughly 28 percent of RFPs. We say no when a hosted wallet would serve the product better than account abstraction, when the team has no plan for paymaster economics, and when a token launch lacks legal counsel on securities classification.

What security track record should a blockchain development company have?

Look for independent audits on every mainnet deployment, not just selected projects. Blockchain Systems has shipped 167 mainnet deployments with zero critical findings and GBP 0 in funds lost, with independent audit before every mainnet launch. Request audit reports and check whether the firm holds ISO/IEC 27001 and SOC 2 Type II certifications, not just a single one-off audit.

What is account abstraction and ERC-4337?

ERC-4337 is an Ethereum standard that replaces a raw private-key wallet with a programmable smart-contract account. Users can sign in with a passkey, pay no gas (via a paymaster), batch multiple actions into one transaction and recover access without a seed phrase. The hard infrastructure behind it, the bundler and the paymaster, is what determines whether it works in production. Blockchain Systems operates an ERC-4337 bundler at 99.98% uptime across nine chains.

How long does a blockchain development engagement take?

Discovery is two weeks at a fixed fee. A smart-account integration typically takes five to ten weeks. A full protocol build takes four to nine months depending on chain complexity, audit scope and compliance requirements. Blockchain Systems provides a written timeline estimate at the end of discovery before any build spend is committed.

Get in touch

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