Inverted binary trees and algorithmic tricks rarely tell you whether an engineer can handle a cascading PostgreSQL deadlock under Black Friday traffic.
At Onvaro, our vetting philosophy focuses on real-world systems: refactoring a messy legacy microservice, reading production telemetry, and assessing how effectively an engineer articulates trade-offs in English.
Discover the three practical evaluations that predict whether an engineer will thrive in your engineering organization.
Evaluation one: the legacy refactor
Candidates receive a small, deliberately untidy service and forty minutes to improve it. We are not looking for a perfect rewrite. We want to see how they read unfamiliar code, which problems they prioritise and how they explain the trade-offs of each change.
Senior engineers tend to stabilise first, add a test around the riskiest behaviour, and only then reshape the design.
We stopped asking candidates to perform tricks and started asking them to think out loud about real systems. The quality of our matches changed overnight.
Evaluation two: the production incident
We walk through a realistic outage using logs, metrics and a short timeline. The candidate leads the investigation, forms hypotheses and decides what to roll back, what to monitor and what to tell stakeholders.
This exercise reveals calm under pressure and clear communication far better than any whiteboard puzzle.
- Forms and tests hypotheses rather than guessing
- Separates mitigation from root cause
- Communicates status clearly to non-engineers
Evaluation three: the design conversation
The final session is a collaborative system design discussion based on a problem one of our client companies has actually faced. There is no single right answer. We assess how the candidate gathers requirements, sizes the problem and adapts when constraints change halfway through.
Throughout all three sessions we also assess written and spoken English, because clear communication is what makes remote collaboration work.
Key takeaways
- Replace puzzles with work that mirrors the real job
- Observe how candidates prioritise in unfamiliar code
- Use incident walkthroughs to test calm and communication
- Assess English throughout, not in a separate test
Written by
Amelia Thorne
Head of Talent
Amelia runs Onvaro's vetting programme and has designed assessment processes for engineering, design and data roles across four continents.
