Pick the endpoint by job type: v3/text or v3/latex for single images (sync), v3/pdf for multi-page documents (async). A 200-page PDF posted to v3/text will just fail - and watch the URL-fetch path, which caps at 10 MB with a 15 second timeout, so slow hosts silently break. If you hit quota walls, they are per app key and can be raised from the console.

Context: Mathpix product page: single images go to the sync v3/text or v3/latex endpoints; multi-page PDFs go to async v3/pdf. Hard limits: JSON bodies 5 MB for v3/text, v3/latex and v3/batch, 10 MB for v3/converter, file upload 1 GB for v3/pdf, and images fetched from a URL cap at 10 MB with a 15 second fetch timeout. Monthly quotas are set per app key.