Senior Backend Engineer

As a Senior Backend Engineer at FlintVellum, you own the bidding and settlement services that connect a collector's final bid to a completed crypto settlement. You build the auction and payment logic, solve the cases that operations cannot afford to get wrong, and use AI tools as part of your daily engineering work. This is a senior individual contributor role, remote with UK or EU preferred; international candidates welcome provided you can overlap UK hours.

What you'll do

• Own bid validation, reserve handling, auction closing and settlement services from design through production.
• Build clear records for cryptocurrency payment events, confirmations, failed transfers and payout reconciliation.
• Handle simultaneous bids, safe retries and duplicate events without losing or repeating a transaction.
• Use AI coding assistants, research tools and review tools to investigate problems, build features and develop tests; verify their output before it reaches production.
• Work directly with operations to turn difficult settlement cases into reliable, maintainable services.

What you bring

• A working understanding of cryptocurrency is essential. Practical experience buying, holding or transferring crypto is strongly preferred; personal experience counts.
• You understand wallets, addresses, networks, transaction fees, confirmations and the difference between Bitcoin, Ethereum and stablecoins.
• You are AI-native in your working habits: you use different AI tools for coding, research, debugging and review, and you can explain where you verify or reject their output.
• You can build, debug and maintain production backend services in Node.js and TypeScript, with sound SQL, transaction handling and accurate money calculations.
• You explain your decisions clearly and take responsibility for the behaviour of the services you ship.

What we offer

• Annual base salary of £90,000-£170,000 plus share options.
• Full-time, remote role.
• Share options are separate from salary; grant size, vesting and other terms would be confirmed with an offer.

About FlintVellum

FlintVellum is an online auction house for authenticated collectibles including watches, graded trading cards, and sports and film memorabilia. The platform accepts settlement in Bitcoin, Ethereum, USDC and USDT, with seller payouts available in GBP or USDC.