Blockchain / Web3 Developer

We are seeking a talented Blockchain / Web3 Developer to join our engineering team on a contractual, project-based engagement. The ideal candidate will have 2 to 4 years of hands-on experience building production-grade blockchain applications, wallet infrastructure, smart contracts, and transaction systems. This role demands a deep understanding of blockchain technology beyond basic wallet integrations, with a strong emphasis on security, scalability, reliability, and production readiness. The position is remote, based in Karachi or Hyderabad, Sindh, Pakistan.

Key Responsibilities
- Design, develop, and maintain blockchain and Web3 infrastructure for production environments.
- Build and integrate secure wallet solutions and wallet management systems.
- Develop end-to-end blockchain transaction flows, including creation, signing, submission, monitoring, and confirmation.
- Integrate external wallets such as MetaMask, WalletConnect-compatible wallets, Coinbase Wallet, and other EVM wallets.
- Implement Web3 authentication and wallet infrastructure providers like Web3Auth.
- Develop, deploy, and integrate smart contracts as needed.
- Build blockchain event listeners, indexing services, and transaction monitoring tools.
- Implement reliable on-chain and off-chain synchronization and reconciliation mechanisms.
- Manage transaction failures, retries, nonce handling, gas estimation, RPC failures, and other blockchain-specific edge cases.
- Integrate with blockchain infrastructure providers such as Alchemy, Infura, QuickNode, or similar services.
- Design systems supporting multiple EVM-compatible blockchain networks.
- Implement secure transaction authorization and fund-movement workflows.
- Develop automated tests for smart contracts, wallet integrations, and blockchain transaction flows.
- Monitor, troubleshoot, and optimize production blockchain infrastructure.
- Collaborate closely with backend, frontend, product, DevOps, and other engineering teams.
- Contribute to technical architecture, documentation, deployment, and ongoing maintenance.

Required Qualifications & Technical Skills
- 2 to 4 years of professional software development experience, specifically in Blockchain / Web3.
- Strong understanding of Ethereum and EVM-compatible blockchains.
- Proficiency in Node.js and TypeScript.
- Practical experience with ethers.js and/or viem libraries.
- Solid knowledge of Solidity and smart contract development.
- Experience integrating and working with Web3 wallets.
- Deep understanding of blockchain transactions, gas fees and estimation, nonce management, wallet addresses, transaction signing and confirmations, RPC providers, on-chain events, and the overall blockchain transaction lifecycle.
- Proven experience developing production-ready blockchain systems beyond prototypes or tutorials.
- Good grasp of blockchain security principles and common vulnerabilities.
- Experience working with relational databases, backend APIs, and asynchronous systems.
- Strong debugging, analytical, and problem-solving skills.
- Ability to write clean, maintainable, scalable, and well-tested code.

Preferred Qualifications
- Familiarity with Web3Auth, MetaMask, WalletConnect, and Coinbase Wallet.
- Experience with blockchain infrastructure providers such as Alchemy, Infura, or QuickNode.
- Knowledge of OpenZeppelin, Hardhat, Foundry, ERC-4337 / Account Abstraction, smart-contract wallets, multisig wallets, stablecoins, and blockchain payment infrastructure.
- Experience with blockchain indexing, transaction monitoring systems, custodial and non-custodial wallet architectures, and MPC wallet infrastructure.
- Proficiency with Redis, queues, event-driven architectures, PostgreSQL, REST APIs, and GraphQL.

Blockchain Security Expertise
Security is critical for this role. Candidates should have practical knowledge of private key and signing security, wallet custody models, smart contract vulnerabilities, access control, reentrancy and replay attacks, transaction manipulation, nonce management, front-running and MEV considerations, secure transaction authorization, smart contract upgrade risks, key management, custody architecture, and secure API design for financial and blockchain transactions.

Technical Environment
The role involves working with technologies such as TypeScript, Node.js, Solidity, ethers.js or viem, Web3Auth, EVM-compatible blockchains, PostgreSQL, Redis, REST APIs, GraphQL, Alchemy, Infura, QuickNode, Hardhat, Foundry, and OpenZeppelin. Experience with other relevant blockchain, Web3, or distributed system technologies is a plus.

We are looking for a developer who has built real-world blockchain/Web3 systems, understands complex blockchain concepts beyond tutorials, can design reliable transaction infrastructure, and has a strong security mindset. The candidate should be capable of independently troubleshooting transaction, RPC, wallet, and infrastructure issues, writing clean and scalable code, and taking ownership of technical challenges from architecture through deployment and maintenance. The ability to work effectively in a fast-paced, project-driven environment while collaborating with a broader engineering team is essential.

Interview Process
The selection process includes an initial HR/recruitment screening, a technical interview, a blockchain/Web3 architecture or practical assessment, a technical discussion, and a final discussion.

This is a hands-on engineering role focused on building and maintaining production-grade blockchain infrastructure, wallet systems, transaction workflows, and Web3 applications.