public challenges

Agentic codingchallenges foryour agent.

Real coding problems, each about the size of a work ticket, that you solve on your own machine with your own AI coding agent: Claude Code, Cursor, or Codex. Start one with a single command, submit when you are done, and get a score for how well you directed the agent across three axes: Direction, Outcome, and Lift.

each challenge page shows its own command

Easy

3 challenges
easybackend60 min

Bookshelf REST API

Junior Backend Engineer interview. Build a small REST API from scratch with CRUD, filters, validation, persistence, and a test suite that would...bookshelf-rest-apidetails easymobile60 min

Offline-First Notes App

Junior Mobile Engineer interview. Initialize a new React Native or Flutter project and ship a notes app that survives force-quit, fakes sync state...offline-first-notes-appdetails easyfrontend60 min

Searchable Product Listing UI

Junior Frontend Engineer interview. Scaffold a product listing page from scratch with search, multi-select filters, and sort. Senior signal: clean...searchable-product-listing-uidetails

Medium

3 challenges
mediumdata90 min

Idempotent ETL Pipeline with Schema Drift

Mid Data Engineer interview. Generate sample CSVs with realistic drift and build a re-runnable pipeline that lands them in a clean table, rejects...idempotent-etl-pipeline-with-schema-driftdetails mediumplatform90 min

Multi-Tenant Feature Flag Service

Mid Platform Engineer interview. Build a feature-flag service from scratch with sticky percentage rollouts, an instant kill switch, tenant...multi-tenant-feature-flag-servicedetails mediumsecurity90 min

Secrets Vault with Envelope Encryption

Mid Security Engineer interview. Build a secrets vault from scratch with per-tenant KEKs, envelope encryption, scoped bearer tokens, an online...secrets-vault-with-envelope-encryptiondetails

Hard

9 challenges
hardrealtime135 min

CRDT Collaborative Text Buffer

Real-Time Collaboration interview. Build a conflict-free replicated text buffer (RGA/LSEQ-style) where concurrent inserts and deletes converge...crdt-collaborative-text-bufferdetails hardsearch120 min

Inverted-Index Search with Ranking

Search / Information-Retrieval interview. Build a from-scratch full-text engine: inverted index, boolean and ranked (TF-IDF/BM25) queries, and...inverted-index-search-with-rankingdetails hardbackend120 min

Multi-Currency Wallet Ledger with Idempotent Transfers

Senior Backend Engineer interview. Build the core double-entry ledger for a multi-currency wallet: atomic transfers, race-safe negative-balance...multi-currency-wallet-ledger-with-idempotent-transfersdetails hardplatform110 min

Multi-Tenant Rate Limiter / Quota Service

Platform / Backend interview. Build a multi-tenant rate limiter with per-(tenant, route) sliding-window limits, burst handling, and longer-window...multi-tenant-rate-limiter-quota-servicedetails hardbackend120 min

Process / Task Orchestrator-Lite

Platform / Infra interview. Build a task orchestrator that runs a DAG with dependency ordering, a global concurrency limit, health checks, and...process-task-orchestrator-litedetails hardai120 min

Production RAG Service with Eval Harness & Cost Guardrails

Applied AI / RAG Engineer interview. Ship a multi-tenant retrieval-augmented service with isolation, cost budgets, semantic caching, and a real...production-rag-service-with-eval-harness-cost-guardrailsdetails harddistributed150 min

Raft-Lite Log Replication

Distributed Systems interview. Build a Raft-style replicated log on a simulated cluster with injectable partitions: leader election...raft-lite-log-replicationdetails harddata120 min

Time-Series Metrics Store

Data / Observability interview. Build an embeddable metrics store that ingests high-rate points, downsamples into rollups, enforces retention, and...time-series-metrics-storedetails hardplatform120 min

Zero-Downtime Schema Migration & Progressive Rollout

Staff Platform / SRE Engineer interview. Migrate a hot, free-text column to a normalized FK on a running service with sustained traffic...zero-downtime-schema-migration-progressive-rolloutdetails

How every challenge is scored

Scores run from 0 to 100. Most of the weight goes to how you direct the agent, because that is the part a careless prompt cannot fake. Passing the tests matters, but it is not enough on its own.

default weights
/ 100

Direction

50 pts

How you steer, verify, and decompose.

Spec Precision · Verification Rigor · Decomposition · Recovery · Intent Fidelity · Engagement

Outcome

35 pts

What shipped, replayed and stress-tested to prove it holds.

Tests · Code Quality · Complexity

Lift

15 pts

How far you beat a solo AI, not just that you passed.

Edge-Case Coverage · Lift over AI

the score, explained
your turn

Pick one and ship it.

Solving challenges, your score, your profile, and the leaderboard are free for developers. Sign up, pick a challenge, and run its command in your terminal.