Senior C# .NET Engineer – Web3, EVM Blockchain and Wallet Integration

Company: Spares 
Employment Type: Full-time  /  Part-time (Flexible)
Experience: 5–8+ years (including 2+ years of hands-on Web3/blockchain experience)

### About the Role

Spares is looking for an experienced Senior C# .NET Engineer with strong hands-on expertise in Web3 technologies, EVM-compatible blockchain networks, and cryptocurrency wallet integration.

The ideal candidate will have proven experience developing scalable backend applications using C#/.NET and integrating decentralized applications with EVM-based blockchain networks. You will be responsible for building secure blockchain-enabled services, integrating Web3 wallets, interacting with smart contracts, and developing reliable APIs that bridge traditional backend systems with blockchain infrastructure.

### Key Responsibilities

- Design, develop, and maintain scalable backend applications using C#, ASP.NET Core, and .NET.
- Integrate Web3 wallets such as MetaMask, WalletConnect, Coinbase Wallet, and other EVM-compatible wallets.
- Implement wallet connectivity, authentication, account management, message signing, and transaction-signing workflows.
- Integrate with EVM-compatible blockchain networks, including Ethereum, Polygon, BNB Smart Chain, Arbitrum, and Base.
- Develop blockchain integrations using Nethereum, Web3 APIs, and JSON-RPC providers.
- Interact with Solidity-based smart contracts and implement ERC-20, ERC-721, and ERC-1155 token standards.
- Build RESTful APIs and backend services for blockchain transactions and smart contract interactions.
- Implement blockchain transaction monitoring, event listening, confirmation tracking, and gas-fee handling.
- Implement secure wallet authentication using cryptographic signatures and Sign-In with Ethereum (SIWE).
- Optimize blockchain connectivity, API performance, and transaction-processing workflows.
- Collaborate with frontend developers, blockchain engineers, and other technical stakeholders.
- Follow security best practices for blockchain integrations, wallet interactions, and API development.

### Required Technical Skills

- Strong hands-on experience in C#, .NET Core / .NET 6+, and ASP.NET Core Web API.
- Proven experience in Web3 application development and blockchain integration.
- Strong understanding of EVM-compatible blockchain architecture.
- Practical experience integrating MetaMask, WalletConnect, or similar Web3 wallets.
- Experience with Nethereum or equivalent .NET blockchain integration libraries.
- Good understanding of Ethereum JSON-RPC, Web3 APIs, and blockchain transactions.
- Experience interacting with Solidity smart contracts.
- Understanding of ERC-20, ERC-721, and ERC-1155 token standards.
- Experience with REST APIs, microservices, and distributed systems.
- Good knowledge of SQL Server or PostgreSQL.
- Experience with Git, CI/CD pipelines, and software development best practices.

### Preferred Skills

- Experience with Ethereum, Polygon, BNB Chain, Arbitrum, or Base.
- Knowledge of WalletConnect v2, EIP-1193, SIWE, and Ethereum standards.
- Understanding of account abstraction (ERC-4337) and Layer 2 solutions.
- Familiarity with Solidity, Hardhat, Foundry, and smart contract testing.
- Experience with Redis, RabbitMQ, Kafka, Docker, and Kubernetes.
- Familiarity with AWS or Microsoft Azure cloud environments.

### Experience & Qualifications

- Bachelor's degree in Computer Science, Software Engineering, or a related field.
- 5–8+ years of professional software development experience.
- At least 2 years of practical Web3/blockchain development experience.
- Experience delivering real-world blockchain applications and wallet integrations.
- Strong problem-solving, debugging, and analytical skills.
- Ability to work independently and contribute effectively within an agile engineering team.

### What We Are Looking For

We are particularly interested in candidates who have hands-on experience building production-ready Web3 applications, integrating cryptocurrency wallets, connecting .NET backend services to EVM blockchain networks, and interacting with smart contracts.

Candidates should be able to demonstrate previous projects involving wallet integration, blockchain transactions, signature verification, and smart contract interactions.

### How to Apply

Interested candidates are invited to submit their updated CV, highlighting relevant C#/.NET development experience, Web3 projects, EVM blockchain integrations, wallet integrations, and smart contract experience.

We are looking for engineers with practical Web3 implementation experience, not just theoretical blockchain knowledge.