Check Your EPUB Before You Publish
Run focused package and reference checks locally. Get a readable report without sending your manuscript to a server.
Drop your EPUB to check its structure
The file stays in this browser tab and is never uploaded.
Single EPUB · Up to 200 MB · No signupChecks included
A fast structural check, with honest limits.
The validator checks ZIP packaging, the container and OPF, required metadata, manifest files and unique IDs, spine references, cover declarations, and common compatibility warnings.
This is a focused browser-based checker, not a replacement for the full publishing conformance suite in EPUBCheck. Use EPUBCheck as the final authority for store submission.