Blockchain / Web3 Developer

We are seeking a skilled Blockchain / Web3 Developer to join our engineering team on a contractual, project-based engagement. The ideal candidate will have 2-4 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 applications.
- 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 required.
- Build blockchain event listeners, indexing services, and transaction monitoring systems.
- Implement reliable on-chain and off-chain synchronization and reconciliation mechanisms.
- Manage transaction failures, retries, nonce management, gas estimation, RPC failures, and other blockchain-specific edge cases.
- Integrate 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
- 2-4 years of professional software development experience with a focus on 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 blockchain transaction lifecycle.
- Experience delivering production-ready blockchain systems beyond prototypes or tutorials.
- Good grasp of blockchain security principles and common attack vectors.
- Familiarity 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 Experience
- Familiarity with Web3Auth, MetaMask, WalletConnect, Coinbase Wallet.
- Experience with infrastructure providers like Alchemy, Infura, QuickNode.
- Knowledge of OpenZeppelin, Hardhat, Foundry frameworks.
- Understanding of ERC-4337 / Account Abstraction, smart-contract wallets, multisig wallets.
- Exposure to stablecoins, blockchain payment infrastructure, indexing, and transaction monitoring systems.
- Experience with custodial and non-custodial wallet architectures, MPC wallet infrastructure.
- Working knowledge of 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/viem, Web3Auth, EVM-compatible blockchains, PostgreSQL, Redis/queues, 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 blockchain technology deeply, designs reliable transaction infrastructure, and maintains a strong security mindset. The candidate should be able to independently troubleshoot transaction, RPC, wallet, and infrastructure issues, write clean and scalable code, and understand production reliability, scalability, monitoring, and failure handling. The ability to work independently while collaborating effectively with a broader engineering team is essential. Ownership of technical problems from architecture through deployment and maintenance is expected, along with comfort working in a fast-paced, project-driven environment.

Application Process
Interested candidates should submit an updated CV/resume, LinkedIn profile, GitHub or relevant portfolio, details of relevant blockchain/Web3 projects, and examples of deployed smart contracts or production blockchain systems where applicable. The interview process includes initial HR 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.