Senior Backend Engineer
Codility
Location: Remote (Poland) - we are currently only considering applicants from Poland. Your application will not be taken into consideration if you are not located in Poland already
Why this role matters
Help unlock the world’s engineering potential by shaping the future of technical hiring !
You will join Codility’s Trust team to pioneer the next generation of assessment integrity, ensuring our platform is secure, fair, and reliable for millions of candidates and enterprise customers globally.
Impact you’ll have
Strengthen enterprise confidence in Codility’s assessments.
Shape the next generation of integrity systems for technical hiring.
Help the Trust team grow by bringing seniority and experience.
What you’ll do
Pioneer AI-Powered Integrity
Drive features across the full stack (Python/Django/FastAPI, React), taking full ownership from design to production and delivery.
Embrace and apply AI/LLM tools and components pragmatically
Develop fraud detection and proctoring solutions that balance security, accuracy and candidate experience.
Improve detection signals and reduce false positives using data-driven approaches.
Scale and Optimize
Make pragmatic architecture choices within established patterns
Champion a culture of engineering excellence, building highly observable, scalable, and resilient systems (metrics, structured logs, traces) that minimize complexity and can handle sudden traffic spikes
Collaborate & Deliver
Translate integrity needs into working features in partnership with Product and UX.
Work closely with Data/ML engineers to integrate models and evaluation pipelines.
Share knowledge: write clear design docs, participate actively in code reviews.
Elevate the Team
Mentor peers through thoughtful code reviews and pairing.
Bring fresh perspectives in AI-native engineering practices (prompt design, retrieval tuning, evaluation design).
Model ownership and initiative: identify risks early, design mitigation options, propose solutions and explain tradeoffs; and see projects through to completion.
Stay curious: propose new technologies, and apply them pragmatically.
What we’re looking for
5+ years of professional software engineering experience
Strong backend in Python and will not shy away from frontend (React or similar)
Track record of end-to-end customer outcomes delivery in distributed remote-teams
Nice to have
Experience in proctoring, fraud detection and/or anomaly detection
Experience in productionizing LLMs in high-stakes domains
Hands-on experience with AWS ecosystem
How you’ll work
Remote-first across Poland.
One-team mindset: no silos, no “not my problem”. We win together.
Ownership & initiative: we expect you to move projects forward, not just execute tickets.
Balance: deliver impact without overengineering; know when “good” is good enough.