Middle/Senior Backend Engineer

the hive

Berlin

Remote

EUR 90,000 - 130,000

Full time

3 days ago

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Benefits offered by this job

Remote worldwide

Benefits program

Job summary

Xsolla is seeking a Middle/Senior Backend Engineer to join the ZK team. You will build scalable blockchain infrastructure and NFT marketplace backends in Go, integrating with ZK/EraVM and various databases, queues, and APIs.

Remote worldwide role with flexible schedule and strong focus on distributed systems and cutting-edge Web3 tech. You will contribute to backend services powering wallet backends, event scanners, and cross-chain connectors, ensuring high availability and robust microservices

Qualifications

2+ years of commercial Go development experience.
Strong experience with MongoDB and PostgreSQL.
Redis for caching and session management; experience with Redis.
Experience designing REST APIs and OpenAPI/Swagger.
Familiarity with Docker and Kubernetes; container orchestration basics.
Knowledge of Ethereum/EVM blockchain integration and related tooling.
Understanding of distributed systems and microservices patterns.

Responsibilities

Develop backend services using Go with Ethereum interactions and RPC integration.
Integrate with ZKstack infrastructure and L1/L2 messaging.
Build wallet backend indexing integrations for real-time token balance tracking.
Design APIs for NFT marketplace and orderbook services with on-chain flows.
Implement smart contract interaction layer using ABI bindings (abigen).
Develop blockchain event scanners with multi-chain support.

Skills

MongoDB

PostgreSQL

Redis

REST APIs

Docker

Kubernetes

Ethereum/EVM

abigen

OpenAPI

Tools

NATS

RabbitMQ

Kafka

go-ethereum

abigen

Job description

ABOUT US

Xsolla is a global commerce company with robust tools and services to help developers solve the inherent challenges of the video game industry. From indie to AAA, companies partner with Xsolla to help them fund, distribute, market, and monetize their games. Grounded in the belief in the future of video games, Xsolla is resolute in the mission to bring opportunities together, and continually make new resources available to creators. Headquartered and incorporated in Los Angeles, California, Xsolla operates as the merchant of record and has helped over 1,500+ game developers to reach more players and grow their businesses around the world. With more paths to profits and ways to win, developers have all the things needed to enjoy the game.

For more information, visit xsolla.com.

ABOUT YOU

We are looking for a Middle/Senior Backend Engineer who is passionate about building scalable blockchain infrastructure and Web3 services to join our Xsolla ZK team. The best candidate will be someone who thrives in a fast-paced, highly collaborative, and exceptionally dynamic setting and is excited to develop backend systems that power NFT marketplaces, smart wallets, and blockchain-based gaming infrastructure.

Strong backend development skills in Go are essential, along with experience in building high-load distributed systems and working with databases. The ability to design resilient microservices architecture and integrate with blockchain networks will be key to your success in this role.

If you're passionate about building the infrastructure layer for next-generation gaming and love working on cutting-edge blockchain technology that enables gamers to truly own their digital assets, we would love to hear from you!

About the project

Xsolla ZK is building a cross-game infrastructure that empowers gamers to freely trade and use their digital assets without barriers. The backend team develops services for:
- Xsolla Bazaar — NFT marketplace for trading digital assets across Ethereum, Polygon, and Xsolla ZK chains
- Web3 Backpack — Smart wallet backend with account abstraction (ZK SSO 4337)
- Blockchain Services — Event scanners, transaction processors, and Web3 connectors
- BFF Layer — Backend-for-Frontend services orchestrating complex Web3 operations
Tech Stack:
- Language: Go (go-ethereum, ethkit, idiomatic concurrency patterns)
- Databases: MongoDB, PostgreSQL, Redis
- Message Queue: NATS, RabbitMQ, Kafka
- API: REST, WebSocket, gRPC, OpenAPI (Swagger)
- Blockchain Infrastructure:
- Key Technical Challenges:

Responsibilities

Develop backend services using Go with ethkit and go-ethereum for Ethereum interactions and RPC integration
Integrate with ZK Stack infrastructure: work with EraVM, system contracts, and L1L2 messaging
Build and maintain wallet backend indexing integrations for real-time token balance tracking and webhooks (via internal indexer or third-party providers)
Design and implement APIs for NFT marketplace and orderbook services, including on-chain order matching and settlement flows
Implement smart contract interaction layer using abigen-generated Go bindings for ERC-20/721/1155 tokens
Build Account Abstraction (ERC-4337) backend support: UserOperation submission and monitoring, paymaster gas-sponsorship logic, session-key issuance and revocation
Develop blockchain event scanners with reorg handling for Ethereum, Polygon, and Xsolla ZK chains
Implement BFF (Backend-for-Frontend) services orchestrating complex multi-chain operations
Design efficient caching and indexing strategies for on-chain data using Redis and MongoDB
Write comprehensive tests including integration tests with local ZKsync test environment
Document APIs using OpenAPI/Swagger specification
Monitor and troubleshoot production systems, handle blockchain-specific edge cases (stuck transactions, gas estimation)

Nice to Have

Required:
- 2+ years of commercial experience with Go
- Strong understanding of MongoDB and PostgreSQL (query optimization, indexing)
- Experience with Redis for caching and session management
- Knowledge of message queues (NATS, RabbitMQ, or similar)
- Experience designing and implementing REST APIs with OpenAPI/Swagger
- Understanding of microservices architecture patterns
- Experience with Docker and container orchestration basics
- Proficiency with Git and GitLab CI/CD
- Solid understanding of distributed systems concepts
Preferred:
- Experience with Ethereum/EVM blockchain integration:
  - Working with go-ethereum library and RPC nodes
  - Smart contract interaction via ABI bindings (abigen)
  - Understanding of transaction lifecycle, gas estimation, nonce management
- Knowledge of ZK Stack / ZKsync Era:
  - EraVM execution model and differences from EVM, including native Account Abstraction on zkSync-family chains
  - System contracts (ContractDeployer, NonceHolder, etc.)
  - L1L2 communication, bridging, and finality/reorg behavior
- Working knowledge of ERC-4337 Account Abstraction:
  - EntryPoint contract and the UserOperation lifecycle
  - Bundler and paymaster roles, gas estimation failure modes
  - Session keys and delegated permissions (ERC-7710 / ERC-7715)
- Familiarity with signature schemes: EIP-712 typed data, ERC-1271 contract signatures, WebAuthn/passkey signers
- Exposure to AA infrastructure providers (any of: Sequence, thirdweb, Privy, Dynamic, Turnkey, Pimlico, Alchemy, Biconomy, ZeroDev, Safe{Core}) for wallet, indexer, or transaction-relay integrations
- Knowledge of token standards (ERC-20, ERC-721, ERC-1155) and their implementation details
- Experience with blockchain event processing: event scanning, reorg handling, finality
- Understanding of DeFi concepts and NFT marketplace mechanics
- Experience with Kubernetes for container orchestration

BENEFITS

We are passionate about fostering a supportive environment for our team, so we prioritize the physical, mental, and emotional well-being of our employees and their families through a comprehensive Benefits Program. This includes medical, dental, and vision, PTO, and a personalized career roadmap for each employee. By investing in professional development through training and educational opportunities, we ensure that our team thrives both personally and professionally. Together, we’re not just building a business; we’re cultivating a community that values creativity, collaboration, and the transformative power of play.

EMPLOYMENT DETAILS

Location: Remote (worldwide)
Employment Type: Full-time
Schedule: 10:00-19:00 (flexible)
Contract: Employment agreement (entity or EOR arranged per candidate location)

EQUAL EMPLOYMENT STATEMENT

Xsolla is dedicated to creating a diverse environment and is proud to be an equal-opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, language, sexual orientation, national origin, genetics, political beliefs, disability, age, marital status, social background or other characteristics.

We are committed to compliance with all fair employment practices regarding citizenship and immigration status.

CONTACT

If you have questions regarding our hiring practices, please contact careers@xsolla.com.

For more vacancies, visit: xsolla.com/careers

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