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.

Our co-founders Olly and Jack were led to this area when a friend was defrauded of £25K when buying their first property. At the time, anti-fraud technology didn’t exist, which meant that completing the anti-fraud checks required in these processes was largely manual. These big life moments should be exciting, but instead are often confusing and scary due to the painful process of completing these paper-based checks and the risk of fraud.

Thirdfort helps businesses to facilitate these anti fraud checks so that individuals know they can transact safely and seamlessly with professionals during these big transactions. Our anti-fraud platform provides a secure way for professionals in regulated sectors like Lawyers, Estate Agents and Accountants to transfer funds and verify sensitive information through app based document checks, facial recognition and open banking.

Over 1,500 businesses now trust Thirdfort to verify their clients. We are FCA regulated and have raised over $33m in capital from leading Fintech investors Breega and Element Ventures, as well as the founders of Zoopla, Funding Circle, Comply Advantage, Tessian, Fenergo and Fidel.

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

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.

If you require any reasonable adjustments during the application or interview process, please let your dedicated Talent Partner know and we'll do our best to accommodate.

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