Software Engineer

The role
We are hiring a Software Engineer, Web3 for Xsolla ZK , Xsolla 's Web3 ecosystem on a zkSync-based L2. It includes: smart wallets built on account abstraction; SDKs that game studios and partners use to bring players on-chain; infrastructure backend services for tokenizing in-game items and currencies; ecosystem dApps: a DEX , an NFT marketplace and an auction. This is a senior fullstack role: you work across backend, frontend and smart contracts. WHAT YOU WILL OWN Features end to end: backend, frontend and production The on-chain / off-chain architecture of your product: what lives in contracts, what lives in services, and how the two stay consistent. You make these decisions and justify them in writing Security and correctness of what you ship: signing flows, interactions with contracts that hold user assets, keys and secrets Production operation of your services, as part of the team's on-call rotation WHAT YOU WILL DO Build backend services in Go and TypeScript: chain indexing, transaction relaying, event processing, APIs for dApps and SDKs Build infrastructure backend services for tokenizing in-game items and currencies Build dApp frontends in React: wallet connection, transaction signing, on-chain state in the UI Integrate smart wallets into products: accounts, paymasters, bundlers Develop SDKs used by game studios and partners Monitor services and contracts in production and take part in on-call Review code Set up and maintain AI tooling in the repositories (Claude Code, Codex, Cursor: rules, context, harness) so the team uses it effectively

Required
Experience 5+ years of commercial software development, with senior-level production experience across backend and frontend dApps that you shipped to production and maintained Web3 libraries and wallets viem and wagmi in production: clients and transports, contract reads and writes with typed ABIs, event subscriptions, wagmi hooks and connectors, caching and invalidation of on-chain state How wallet signers work: EOAs, browser and embedded wallets, smart accounts; personal_sign (EIP-191) and typed data (EIP-712); the EIP-1193 provider; network switching Hands-on experience with smart wallets: UserOperations, gas sponsored via paymasters, signature validation for contract accounts (ERC-1271) Backend Go and TypeScript (Node.js) for production services Processing on-chain events: idempotency, reorg handling, retries Asynchronous messaging and event-driven design (Kafka, RabbitMQ or NATS ): delivery guarantees, ordering, reprocessing Relational databases (PostgreSQL) and caching (Redis) Designing REST and gRPC APIs: versioning, backward compatibility Frontend React and TypeScript: rendering model, state management, performance Web security fundamentals: XSS , CSRF , CSP , safe handling of signatures and keys in the browser Smart contracts Reading and understanding Solidity contracts and the EVM (storage, gas, call semantics, proxy upgrade patterns, access control) well enough to integrate with them safely and review changes Common contract vulnerability classes (reentrancy, front-running / MEV , oracle manipulation, signature replay) and how they affect the off-chain side Operations Containers and orchestration (Docker, Kubernetes) at the level of deploying and debugging your own services Observability (we use Datadog; experience with Prometheus, Grafana, ELK / Graylog or OpenTelemetry also counts): metrics, logs, tracing and alerting for services and contracts; diagnosing incidents in production Engineering practices Testing: unit, integration, E2E Git, CI/CD (GitLab CI or similar) AI-assisted engineering Daily hands-on use of AI coding tools (Claude Code, Codex, Cursor) for development and review, including configuring them for a repository English Spoken English at B2 level or higher

Nice to have
zkSync / ZK Stack and the specifics of the zk -rollup stack Designing, writing and testing smart contracts in Solidity with Foundry; deploying and upgrading them safely Building ERC-4337 infrastructure yourself (bundlers, paymasters); EIP-6963, EIP-5792 DeFi: DEX and AMM mechanics NFTs and marketplaces: ERC-721, ERC-1155, auction mechanics L2 infrastructure: running nodes, indexers, bridges Designing SDKs for external developers Gaming domain experience