Design stale job listing detection
PremiumBackend systemMedium
- Staleness scoring
- Evidence aggregation
- Audit trail
Quick answer
This backend system interview question asks you to design stale job listing detection. Aim for a design that meets its requirements at the stated scale, then explain its main components, data flow and trade-offs. Interviewers want to see how you scope the problem, size it and defend each choice.
The problem
Design stale job listing detection for a job board: a backend that finds job posts that are probably filled or expired, scores them from several evidence sources and takes staged, reversible actions. The hard parts are explaining every decision and not hiding live jobs that employers pay for.
A posting can go stale in many ways: the apply link returns 404, the job vanishes from the employer’s applicant tracking system (ATS) feed, the page says “position filled”, or job seekers report it. No single signal is reliable, so the system combines them, records why, and lets employers appeal.
What must the system do?
- Evidence-based score: Combine apply-URL checks, ATS feed presence, page text, job seeker reports, employer activity and listing age into a staleness score with its evidence.
- Staged, reversible actions: Move a listing through stages (normal, demoted, flagged and employer asked to confirm, hidden from search, closed); every step can be undone.
How well must it do it?
- Precision first: At least 98% of hidden listings must truly be closed; a paid listing needs two independent signals before it is hidden.
- Freshness: A listing whose apply link is found dead is hidden within 48 hours of the first failed check, once the evidence rules allow it.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Staleness scoring
- Evidence aggregation
- Audit trail
- Reversible actions
- Web crawling politeness
- ATS feeds
How you’ll practise
- Requirements
- Estimate
- API and data
- High-level design
- Deep dives
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any backend system design round.
- Clarifies the requirements before drawing anything
- Uses a few numbers that actually change the design
- Draws a clear path from the client to storage
- Picks storage and caching with reasons, not by habit
- Explains what breaks first under load and how to fix it
- States trade-offs openly instead of claiming a perfect design
Questions people ask about this interview question
- Which design type is this question?
- It is a backend system question. You design stale job listing detection and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the requirements: what the system must do, how well it must do it and which numbers change the design. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team