About this role
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