Full Stack Engineer (Trust domain)

Why this role matters?

Codility’s mission is to help companies build trust in technical hiring. In the Trust team, we ensure that assessments are secure, fair and reliable. Enterprise customers depend on us to deliver accurate signals about candidate skills. This role is about strengthening our assessment integrity systems that include similarity detection, proctoring and fraud prevention, while ensuring scalability, usability and business impact.

What you’ll do

Build Integrity & AI Systems

• Deliver features across backend (Python/Django/FastAPI) and frontend (React) — end-to-end responsibility for production outcomes.
• 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.

Own Systems at Scale

• Make pragmatic architecture choices within established patterns: event-driven, AWS primitives.
• Build observability into features: design services to emit metrics, structured logs, traces and clear health signals from the start.
• Keep operational excellence front of mind: monitoring, logging, testing, alerting and reducing complexity.
• Apply OWASP Top-10 for LLM apps to ensure security in AI-augmented features.
• Follow compliance guidance (EU AI Act transparency/fairness requirements) with support from Product, Security and Legal.

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, but apply them pragmatically.

What we’re looking for

• 6+ years of professional software engineering experience.
• Strong backend (Python/Django/FastAPI) and experience in frontend (React or similar).
• AWS fluency (RDS, S3, SQS, Lambda/ECS/EKS, DynamoDB, Kinesis) and event-driven architecture.
• Track record of end-to-end feature delivery in distributed remote-teams.
• AI-native baseline:
• Experience shipping LLM-backed or retrieval-augmented features.
• Can run simple evals (precision/recall, groundedness, harmful content).
• Understands common LLM risks (prompt injection, data leakage) and mitigation.

Nice to have

• Experience in proctoring, fraud detection and/or anomaly detection
• Experience in productionizing LLMs in high-stakes domains
• Hands-on experience with Infrastructure as Code (IaC); proficiency with Terraform

How you’ll work

• Remote-first across Poland, Germany, UK and US. Outcomes mindset first.
• 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.

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.