Senior Blockchain Engineer for On-Chain Indexer Setup Program

Keystone Digital

Contract · Remote · Flexible hours

About the role

Keystone Digital is building a next‑gen mobile marketplace that will launch on major app stores this quarter. As a Blockchain Engineer you will align smart‑contract logic with the mobile backend to ensure seamless token transactions and NFT listings. The project, codenamed "Nebula Vault", focuses on secure, low‑latency integration between the app and our blockchain layer.

Key responsibilities

• Design and deploy Solidity contracts for in‑app token swaps, targeting Ethereum L2 solutions.
• Integrate contracts with the mobile backend using Web3.js and Python FastAPI gateways.
• Implement gas‑optimization strategies and automated testing pipelines in Hardhat.
• Collaborate with iOS/Android teams to synchronize state updates via push notifications.
• Conduct security audits and remediate findings before the store release deadline.
• Document contract interfaces and versioning for future mobile feature rollouts.

Must-have skills

• Advanced Solidity development and smart‑contract lifecycle management.
• Proficiency with JavaScript, Python, and REST API integration.
• Experience in blockchain security audits and gas optimization.
• Familiarity with mobile backend frameworks and CI/CD pipelines.
• Strong problem‑solving skills in cross‑platform environments.

Nice to have

• Knowledge of Polygon or Arbitrum scaling solutions.
• Previous work on NFT marketplaces or tokenized asset platforms.