Senior Software Engineer

We’re on a mission to protect society from fraud and money laundering. We’ve already protected over 3 million people through life’s big transactions.

Fraud and regulation are rising, costing the UK economy over £100bn every year; this makes it more difficult for businesses to protect themselves and their clients - individuals like you and me - from fraud and money laundering.

About the role:

You'll join Thirdfort at an exciting moment for Tenant Referencing. We're rebuilding the product from the ground up, moving it off a legacy platform onto Thirdfort's strategic engineering platform (Go, Temporal-based workflows, cloud-native). You'll be one of the first permanent engineers on a newly-formed squad, with real scope to shape how tenant referencing gets architected and make technical calls on a live migration. It matters beyond the tech, too. Tenant referencing is where our fraud-prevention mission meets something that matters to people directly: renting a home.

We're looking for someone who takes ownership, is comfortable without a fully mature spec, and is pragmatic about tooling, including using AI where it helps them move faster.

For this role, we would love this person to be able to join us in our London office two times a week as being together as a team is valuable for us but ultimately, we trust our team to decide what works best for them.

You will achieve your mission as our Senior Software Engineer by:

• Helping lead the rebuild of our tenant referencing product, migrating it from our legacy platform onto Thirdfort's strategic engineering platform (Go, Temporal-based workflows), working across both systems during the transition

• Designing and building backend services and APIs that power tenant referencing checks, and contributing to our frontend (React/TypeScript) and mobile platforms when needed

• Making independent architecture and delivery decisions on a fast-moving, still-forming squad, working closely with our Product & Tech Lead

• Upholding engineering quality through testing, observability, and code review, as we build permanent engineering ownership into the team

• Partnering closely with Ops and Support to understand real tenant referencing workflows and translating that understanding into good technical decisions

• Using modern engineering practices, including AI-assisted development, to build new check types and features quickly without sacrificing quality

• Mentoring and uplifting engineering practices across the squad as it grows

You may be right for this role if you:

Hard requirements:

• Have strong backend service experience in a modern programming language, with the ability to ramp up quickly in Go

• Have experience designing, building, and integrating APIs

• Have experience working in cloud environments (AWS and/or GCP)

• Have taken ownership of ambiguous technical problems and seen them through with minimal oversight

Nice to haves:

• Have experience with workflow orchestration or event-driven systems (e.g. Temporal)

• Are comfortable using AI coding tools (e.g. Copilot, Cursor, Claude Code) as part of your everyday workflow

• Have experience working across a legacy-to-modern platform migration

• Have some experience with React/TypeScript and/or mobile development
  
  

“Studies show that women and other less represented groups are less likely to apply for roles unless they meet every requirement. We believe in building a diverse team, valuing different skills and experiences and so if you don’t think you have all the requirements listed here but feel this could be a role and environment you’d thrive in, we would still love for you to apply."

Our Benefits:

We've created our benefits package to reflect Thirdfort's mission and values. Everything we do is designed to build on trust, and we extend this promise to our team by investing in their physical, mental, and financial security to support them through life's big moments. Ultimately, our benefits exist to empower our people, ensuring everyone feels deeply supported, trusted, and equipped to do their best work.

When you join Thirdfort, you'll get immediate access to our employee benefits package that aims to support you across these areas:

• Compensation: up to £100,000 base salary

• Location - London Office - twice per week

• Share options for all UK employees

• Annual leave allowance of 26 days, increasing to 30 with tenure and the option to buy additional days

• Uncapped personal development budget

• Flexible working hours

• Private healthcare (AXA)

• Enhanced parental and sick leave

We're committed to building an inclusive, equitable and diverse culture where everyone has a chance to make a difference. We're purposefully building a team of problem-solvers that reflect our values, which is why we hire from all backgrounds. If you're a curious, kind individual who takes ownership, you'll be a great Thirdforter.