A GIF has no 24, no 30 and no 60.

Each frame's delay is stored as a whole number of centiseconds — hundredths of a second. Not milliseconds, not a rational, not a rate in a header. So the only frame rates a GIF has are 100 divided by a whole number: 100, 50, 33.33, 25, 20, 16.67, and so on down. The three commonest frame rates in video are not among them.

The engine is free and needs no account. An exporter asked for 30 picks 3 ticks and records nothing about it, so the clip plays at 33.33 fps — 11.1% fast. The error is per frame, so 300 frames come out at 9.00 seconds instead of 10, and a second short again on every loop. And there is a fix almost nobody uses: mix the delays. Nothing requires every frame to carry the same one, and [3, 3, 4] over three frames sums to 10 ticks, which averages to exactly 30 fps. 24 works the same way. 60 does not — its pattern needs a 1‑tick frame, and every browser replaces that with 10, which puts the real ceiling at 50 fps. Every lane ships a worked example that costs nothing. Writing the report needs credits.