Senior Software Engineer (AI-Driven Fraud Prevention Systems)

💻 Job Title: Software Engineer

💰 Salary: up to ~£100k (+ very generous early-stage equity, ~£80k)

📍 Location: Central London, EC1 (3 office day/week)

🏦 Company: B2B FinTech / Fraud Prevention

👥 Employees: ~30

💸 Funding: $15m+ (Series A)

This London startup is building a new intelligence layer designed to bring more context and security to digital payments. Their technology analyses transactions in real time, gathering signals from multiple sources to determine whether a payment is legitimate or potentially fraudulent.

The platform combines distributed data systems, real-time investigations and AI-driven decisioning to help financial institutions detect scams while allowing legitimate payments to flow without unnecessary friction. Within 2 years of being founded, they're working with most Tier 1 banks and payment providers in the UK - and are about to launch in the US! 🚀

Hiring a Software Engineer to join the core product team building the investigation engine itself — the APIs and UI that plug into bank payment flows, the integrations that pull in evidence from clean and messy sources alike, and the AI agents that reason over that evidence to make a real-time call. This isn't a "build to spec" role: most of the evidence this system needs doesn't come from clean APIs, so a big part of the job is deciding what "good" looks like and owning the consequences of that call. AI here isn't a feature bolt-on — engineers are actively building and shipping the LLM-powered agents that drive the investigation itself.

✅ Must have requirements:

• Strong backend engineering background (Python and/or Kotlin, or similar) with real production experience on fault-tolerant, distributed systems

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• Comfortable owning ambiguous problems end-to-end, from a loose spec through to something shipped, observed and iterated — without a big team or heavy process to lean on
• Genuine hands-on experience building with AI agents / LLM orchestration in production — not just using AI coding tools, but shipping agentic systems that make live decisions
• Product instinct — you ask "who's this for, what's the smallest useful thing I can ship" rather than just executing the ticket
• Comfort working with sensitive or regulated data, with a real understanding of data governance
• At least 3-4 years experience shipping production software

👍 Bonus points for:

• Fintech, payments, or other regulated-industry experience
• Frontend comfort in TypeScript/React (full-stack leaning backend experience)
• Early-stage startup experience
• Experience integrating messy, unstructured or third-party data sources (scraping, semi-documented APIs)

Not ticking every box? Research shows women and under-represented candidates are less likely to apply if they don't meet 100% of a spec — please apply anyway, or drop me a note to discuss fit.

🛂 Visa sponsorship available if needed.