Job board - search, apply, and the recruiter's inbox

Why this design

A job board is a full-text and geo search over a catalogue that turns over completely every month, plus a delivery system that carries applications to wherever the recruiter really works. Interviewers use it to see how you index fast-changing documents, how you make deletion reliable rather than eventual, and whether you notice that most listings are imported from somebody else's system on a timer.

What you will learn

• Why removing a closed job from search is the product's freshness promise, not housekeeping.
• Why expiry has two mechanisms: an outbox delete and a valid_through filter on every query.
• Why 80% of jobs arrive by feed, re-fetched every four hours, and why a content hash makes that cheap.
• Why an application is routed to the employer's ATS or an inbox, and is one row per candidate per job.
• Why a hot remote job takes 2,000 applications in 48 hours, and what the inbox's sort order decides.
• Why a job that is filled but never closed is the failure this board cannot see.

How to read this board

1. Press play once: the walkthrough follows a search, an application, and then a job closing.
2. FIND & APPLY: query, freshness filter, index, apply.
3. THE RECRUITER'S INBOX: routing to an ATS or the board's own inbox.
4. POSTINGS & EXPIRY: direct posts, feed imports, the outbox, the sweeper and the indexer.
5. DATA MODEL: jobs with their own expiry date, and applications unique per candidate.
6. Then pages 1 to 6 in order: requirements, capacity, storage, availability, how it works, deployment.

Two customers with opposite needs: seekers want every live job and no dead ones; recruiters want the right hundred applications, not two thousand.

Ask these before designing

• Where do jobs come from? Direct posts by recruiters, or feeds from applicant tracking systems? Usually both, with feeds the large majority.
• Where do applications go? Our own inbox, the employer's ATS by webhook, or a redirect to the employer's site? Each has a different delivery guarantee.
• How fast must a closed job disappear? Minutes is achievable for jobs we are told about. Jobs we are not told about are the real problem.
• Is a listing paid? A paid listing has a hard end date, which is the one expiry you can always trust.
• Can a candidate apply twice to one job? No - and a double tap on Apply must not send two.

Functional

• Search by keywords, location radius, remote, salary range, seniority, posted date.
• Apply with a stored résumé and screening answers in one step.
• Route each application to the employer's ATS or to the recruiter inbox.
• Recruiter inbox: list, sort, filter and change stage on applications.
• Recruiters post, edit and close jobs; employers' ATS feeds are imported on a schedule.
• Jobs expire automatically at valid_through.

Non-functional

• Search p95 under 250 ms at 8,300 queries/s peak.
• Closed or expired jobs out of search within 5 minutes of the board knowing; and never shown past valid_through.
• Application accepted exactly once per candidate per job, durably, before the seeker sees "sent".
• ATS delivery p99 under 2 minutes, retried for 72 hours.
• Search availability 99.95%; apply 99.9%.

Out of scope

Recommendation and matching models, sponsored-listing auctions, messaging, interview scheduling, salary estimation, employer reviews.