Flag Checks
Paste a FastFlag list and have it validated against all 24,086 known flags. Accepts JSON or a plain list of names.
Existence check
Catch typos and made-up flags. A name that doesn't exist is silently ignored by the client, so it's easy to miss.
Open →Duplicate check
Find flags listed more than once, and flag the cases where the repeats disagree on a value.
Open →Stability check
See which flags fall outside the curated set — real, but untested and more likely to misbehave.
Open →Nothing you paste is stored — checks run against the flag index and the result is returned straight back to your browser.