Pick the one your invitation named.

Both are build exercises rather than quizzes, both are marked by machine against a reference implementation, and both use entirely fabricated data. They share nothing else: choose the one for the role you applied to.

Ledger Engineer

Ledger Arena

We stream you a broker event feed. You keep the book, and we score it continuously against a reference ledger.

BuildA double-entry ledger that ingests a live event stream and answers state checkpoints.
Scored onPosting correctness, checkpoint state, resilience, liveness.
NeedsOutbound HTTPS. No public address, no certificate, no cloud account.
LanguageAny. The protocol is the interface.

Start the ledger assessment → AI Engineer

AI Arena

We send you questions about a book of client records. You build the agents that answer them, and know when not to.

BuildA multi-agent ecosystem in Agno: a router and specialists behind one answer contract.
Scored onGrounded correctness, abstention and refusal, orchestration, safety.
NeedsOutbound HTTPS. We supply the model and pay for it.
LanguagePython, with Agno pinned.

Start the AI assessment →

True of both

One address, one candidate Your key is your identity. A second address is not a second chance.

Practice is unlimited And it tells you exactly what it expected, every time.

Three scored attempts, then one final Each attempt is fresh data, so a retry is a new problem rather than a retake.

The final score is withheld You see that the run finished, never how it went.