React Web3 Jobs in San Francisco, California, United States

Company Description

Paena is building the first on chain earned wage access platform that connects decentralized liquidity to real workers living paycheck to paycheck. We provide instant cash advances with smart contract based repayment and yield subsidized fees that dramatically undercut legacy earned-wage-access incumbents.

You will lead core engineering and product development at the intersection of fintech infrastructure, DeFi protocols, and consumer systems. We use crypto for good. Your work will directly shape how capital flows from on chain markets to off chain users at scale.

Role Description

We are hiring founding full stack/Solidity engineers to join us in San Francisco for this upcoming batch starting in January. This is a rare chance to join at day zero, ship product to real users, and help define how workers around the world access their earnings.

What You Will Do

• Build the core worker experience for requesting and repaying cash advances using React Native, TypeScript, and modern mobile tooling
• Design, implement, and audit Solidity smart contracts for earned wage access, including ERC 4626 >
• Integrate and build on top of DeFi protocols such as Morpho, Aave v3 with forward looking support for Aave v4
• Architect backend systems in TypeScript or Python using Node.js frameworks, relational databases, and event driven job queues
• Implement ACH debit and bank payment flows, reconciliation, and failure handling across off chain and on chain systems
• Build smart wallet infrastructure using embedded wallet and key management systems such as Privy or Turnkey
• Design secure transaction orchestration across wallets, payment rails, and smart contracts
• Ship fast, talk directly to users, and iterate based on real feedback
  
  

• 3+ years of experience working as a software engineer at a fintech or web3 company or early stage startup, including experience shipping production systems
• Completed a Bachelor’s degree in Computer Science, Engineering, or a related field, or graduating in December of this year
• Extremely strong familiarity with modern web and backend stacks including TypeScript, React, React Native, Node.js, and relational databases
• Strong familiarity with Solidity and EVM based smart contracts, or a demonstrated ability to ramp up extremely quickly and ship audited on chain code
• Familiarity with DeFi primitives and protocols such as ERC 4626 vaults, Aave v3 or similar money markets, and stablecoin based systems
• Experience integrating payments and financial infrastructure such as ACH debit, bank account linking, or transaction reconciliation
• Proven experience designing and shipping systems within structured engineering organizations, including system design, code review, testing practices, and production operations
• Ability to lead technical execution, set engineering standards, and mentor or manage other engineers as the team grows
  
  

• Build real financial infrastructure that materially improves people’s lives
• Work on one of the rare YC crypto companies focused on real world users and cash flow
• Own large technical surface area from protocol design to user impact
• Competitive compensation, meaningful equity, and high autonomy
• Backed by top tier investors with long term conviction in the space