Postgres
Order ingestion
- Duplicate events
- Transactions
- Constraints
- Query behavior
Production-behavior assessments
Backend assessment ranges for real infrastructure work.
Invite a candidate into a disposable system with Postgres, Redis, queues, and S3-like object storage. See how they handle retries, stale data, partial failures, and consistency bugs.
75m
typical range
4
first data-system ranges
0
AI hire/no-hire verdicts
Live range ready
Postgres, queue, and object storage are isolated for this session.
upload.ts
worker.ts
README.md
1
import { storage, db } from "./clients";
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import { enqueue } from "./queue";
3
4
export async function createUpload(file) {
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if (file.size > 10000000) {
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throw new Error("file too large");
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}
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const key = safeObjectKey(file.name);
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const url = await storage.signedPutUrl(key);
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await db.upload.create({ key, status: "pending" });
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await enqueue("object.created", { key });
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return { key, url };
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}
$ run visible-tests
PASS accepts valid png upload
PASS stores metadata row
FAIL rejects oversized object
FAIL duplicate event creates second invoice
The first range pack is concrete by design.
Each range has a named system, real services, visible tests, hidden checks, logs, and follow-up questions.
Redis
Cache correctness
- Invalidation
- TTLs
- Stale reads
- Fallback behavior
Queue
Worker idempotency
- Retries
- Duplicate delivery
- Dead letters
- Operational debugging
S3-like
Upload pipeline
- Signed URLs
- Metadata
- Access control
- Orphan objects
What actually happens in a range.
A candidate does not solve a riddle. They work inside a bounded backend system and leave behind observable engineering evidence.
01
Invite
Choose a calibrated range, send a private link, and let the candidate start when the environment is ready.
02
Work
The candidate edits code, runs visible tests, inspects service health, and handles realistic state and failure modes.
03
Review
Interviewers get tests, changed files, logs, timeline, rubric scores, and concrete follow-up questions.
Safe to pilot with real candidates.
Run realistic backend assessments without connecting candidate code to your production systems. Each range is isolated, time-bounded, and designed so interviewers can trust the signal without adding operational risk.
Isolated candidate sessions
Disposable runtime per assessment
Sandbox-only credentials
No production secrets or customer data
Protected evaluation signal
Hidden tests stay outside the workspace
Bounded network access
External access is off unless a range needs it
Built for hiring conversations.
The report does not pretend to replace judgment. It gives engineers a sharper next interview.
Visible and hidden test resultsincluded
Timeline, logs, and changed filesincluded
Follow-up questionsincluded
Automated hiring verdictsexcluded
Private pilots
Request pilot access.
We are looking for backend hiring teams that want practical signal from real infrastructure work. Tell us what you are hiring for, and we will follow up with a sample range and pilot plan.
Good fit: teams hiring backend, platform, SRE,
data, or infrastructure engineers.
- Early pilots include founder onboarding.
- Reports focus on technical follow-up, not automated hiring verdicts.
- Security and sandbox details are available before any candidate session.