What to assess in a backend engineer
Many backend teams work in Python, Go, Java or Ruby. SynergicHire's hands-on code is TypeScript on Node, so use the screen's conversation and whiteboard for design and language experience, and the coding round for how the candidate builds and verifies a service with an assistant.
- System design: services, queues, caches and the trade-offs between them.
- Data modelling: schemas, indexes, transactions and consistency.
- Reliability: timeouts, retries, idempotency, backpressure and graceful degradation.
- API design: contracts, versioning, pagination and error handling.
- Operations: logging, metrics, alerts and what to do in an incident.
- Working with AI: using an assistant for boilerplate while owning the design and the tests.
Screening questions for backend engineers
Design sections open a whiteboard. The board is saved with each answer and described to the screener, so it can ask about the diagram itself rather than only the words.
- Draw how an order flows from checkout to fulfilment. What happens to checkout when that queue backs up?
- How would you design rate limiting for a public API used by thousands of customers?
- A table has grown to a few hundred million rows and one query is slow. Walk through your approach.
- How do you make a job that charges customers safe to run twice?
- Tell me about a production incident you handled. What did you change afterwards?
The backend coding round
The coding round runs a Node.js service with starter files and tests, in a Cursor-like IDE with a terminal, completions, file-aware chat and an agent. It shows how a candidate reads an unfamiliar codebase, uses an assistant, and checks the result. It does not run Python, Go or Java.
You choose guarded or unguarded mode, and the server enforces it. The server reruns the tests when the round ends.
AI-fluency signals for backend work
| Signal | What it tells you about a backend engineer |
|---|---|
| Time to first prompt | Whether they read the service and its tests before reaching for the assistant. |
| Prompt quality | Whether prompts specify constraints: concurrency, failure handling, data shape. |
| AI-generated share | How much of the final service code came from accepted AI output. |
| Verification | Whether they ran tests or edited code within 90 seconds of accepting it. |
| Over-reliance flags | Large accepted blocks, such as retry or transaction logic, never reviewed. |
| Recovery | What they did when the assistant's code failed a test or ignored an edge case. |
From scores to a decision
The screen, the coding round, the hiring manager round and any bar raiser all sit on one scorecard. The lowest verdict sits next to the average, so a strong no is not hidden by a good mean. A named person records the outcome.
Questions
Can SynergicHire assess backend engineers who work in Python or Go?
Partly. The AI screen can cover design and language experience in conversation and on a whiteboard. Hands-on code runs in TypeScript on Node, so the coding round shows how they build with an assistant rather than their fluency in another language.
Does the screen include system design?
Yes, if your plan includes it. A whiteboard opens beside the conversation and the screener can ask about what was drawn.
What does the coding round run?
Backend coding rounds run a Node.js service with tests and a terminal. Other stacks are React, Next.js and React Native (Expo).
Is the decision automated?
No. The AI assesses and gives advice with citations. A named person signs off every round and records every outcome.