Free browser tool
NCCL log decoder
Classify covered NCCL and initiating CUDA signatures across rank logs. The decoder marks watchdog timeouts and launcher exceptions as secondary so the loudest survivor does not automatically become patient zero.
The decoder classifies covered signatures and marks timeout and launcher wrappers as secondary evidence. Logs stay in this browser.
What this decoder can establish
It recognizes a bounded set of literal signatures, extracts rank labels when present, and identifies the first non-wrapper finding by file order. It is useful for fast triage and for deciding which log to open first.
What it cannot establish
It cannot correct clock skew, reconstruct missing ranks, prove temporal order across separate files, or diagnose an unseen signature. Use the complete pipeline when the evidence is split, incomplete or ambiguous.
Need the repeatable rank-by-rank method?
Use the task guide to collect, normalize, classify and verify the first failed rank.
Open the first-rank guide