Sofia-based I Senior Product Engineer

About the role

ABOUT INFINITE LAMBDA

Infinite Lambda is Europe’s fastest-growing data and AI consultancy. We empower leading companies to scale and become data-first through agile, cloud-native solutions and cutting-edge practices.

Our mission is to bring top professionals together to make an impact at the intersection of tech and sustainable growth.

Headquartered in London and having distributed teams based in the UK, France, Hungary, Slovakia, Bulgaria, Vietnam, Singapore, Italy, Romania and now expanding to South America we embrace diversity and make sure everyone is happy to be their true self at work. We have already started building teams in Brazil, Argentina, and Chile, and are looking forward to welcoming more teammates to contribute to meaningful projects. Together, we can grow, learn, and experiment with the cutting-edge data and AI technology (dbt and Snowflake among others) that we are all excited about.

ABOUT THE ROLE

We are hiring a Senior Product Engineer to own a subsystem of Flowline https://infinitelambda.com/flowline-legacy-data-migration/, our platform for migrating legacy ETL estates to dbt, Fivetran and cloud data warehouses.

Mission: Own a Flowline subsystem from spec to production, keep its quality high as agents write more of the code, and help associates grow into the same role.

1. Reports to: CPO

2. Anticipated start date: From Dec 2026 onwards

3. Location: Sofia (Bulgaria), hybrid

- You and the Product Engineering team will work from a coworking space in Sofia 2 days per week

- Every couple of months, the international Product team and the CPO will be Sofia for an in-person sync and collaborative sessions.

Interview process

1. Intro call (with TABP): 45-min

2. Take-home exercise: up to 4 hours to complete

3. Technical interview (with Product team): 90-min

4. Cultural chat (with Executive member): 45-min

What You’ll Do

- Owns a subsystem of Flowline end to end, for example a source-vendor extractor, the BI conversion path, or the IDE extension. Accountable for its correctness on client estates.

- Writes the specs for their subsystem and for cross-cutting features, with acceptance criteria. The Founding Architect reviews changes to the conversion contract and the architecture.

- Runs several agents in parallel and asynchronously on their subsystem. Writes and maintains the skills, rules and eval cases those agents depend on.

- Reviews agent-authored and associate PRs in their area. Rejects code that drifts from spec or that the author cannot explain.

- Supports Infinite Lambda delivery teams on live migrations. Triages conversion defects raised at UAT, fixes the root cause in the converter, and updates the runbook.

- Mentors associate engineers on spec writing, code review and modernisation patterns, and takes part in hiring.