janek26

Staff Engineer • product infrastructure • open source

I build infrastructure people rely on

I build user-facing products and developer infrastructure end-to-end. The work has reached 300,000+ wallet users and ~115K weekly library downloads.

Explore Work Let's Talk

Field Note

Selected Impact

Outcomes, scale, and shipped infrastructure that are easy to evaluate

Proof 01

Argent X

Senior Engineer · Lead Engineer

Built the first Starknet browser wallet from zero, owning extension UI, background service workers, dApp connector APIs, and transaction pipelines.

Impact

300,000+ Chrome users · 5.0 stars across 89,500 ratings

Wallet Infrastructure

StarknetTypeScriptReactOpen Source

Proof 02

Vesu.xyz

Founding Engineer

Bootstrapped the lending product from zero: borrowing flows, real-time position tracking, and risk dashboards.

Impact

$50M+ TVL · largest lending protocol on Starknet

DeFi Protocol

DeFiStarknetSmart ContractsFull Stack

Proof 03

starknet.js

Maintainer & Core Contributor

Co-developed the ecosystem’s core JavaScript library, authored major v3 architecture and modernization work.

Impact

~115K weekly downloads · standard Starknet developer tooling

Core Library

StarknetTypeScriptLibraryOpen Source

Proof 04

viem

Contributor

Contributed to a leading modular Ethereum library for modern TypeScript applications.

Impact

3,400+ stars · used across modern Ethereum apps

Web3 Library

EthereumTypeScriptWeb3Open Source

Proof 05

Rainbow Browser Extension

Staff Engineer

Revived the browser extension, restored shipping velocity, and shipped EIP-7702 and EIP-5792 support.

Impact

Modernized one of the most-used Ethereum wallet extensions

Browser Extension

ExtensionWeb3UXBrowser APIOpen Source

Field Note

Speaking & Events

Public technical work, not the main proof, but useful signal

Talk 01

Building Web3 Tools That Matter

StarknetCC

StarknetCC is the largest community conference in the Starknet ecosystem, bringing together builders, developers, and enthusiasts to explore Cairo and Starknet innovation.

StarknetWeb3Cairo

Talk 02

Web3 Development with Starknet.js

App.js

App.js is the largest JavaScript event in Europe, bringing together thousands of developers. Sharing insights on modern web3 development and JavaScript tooling.

JavaScriptWeb3TypeScript

Working Model

About Me

I’m a product-minded staff engineer with 8+ years shipping user-facing products and developer infrastructure end-to-end. The work spans browser extensions, TypeScript libraries, protocol integrations, and full-stack systems.

I’m strongest where product quality and deep technical systems meet: wallet transaction flows, dApp connector APIs, library architecture, account abstraction, and fast 0-to-1 execution.

Currently available for freelance work and consulting. I specialize in Web3 architecture, TypeScript libraries, smart contract integration, and full-stack development.

Available

Freelance / Consulting

Proven Scope

✓ Browser extensions used by hundreds of thousands
✓ TypeScript libraries with six-figure weekly downloads
✓ Protocol products scaled from zero to meaningful TVL
✓ Production systems at 7M+ MAU scale

Useful For

✓ Product engineering for crypto and developer tools
✓ Wallet architecture and transaction pipelines
✓ TypeScript library design and modernization
✓ Technical leadership for 0-to-1 execution