CONVERT
HTMLZ → MOBI

Yes. The free tier accepts files up to 100 MB without registration, email capture or watermarks. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.

Yes, provided the HTMLZ itself has a well-formed ToC. Calibre reads the navigation structure and writes an equivalent ToC into the MOBI. If the source lacks a ToC we can generate one from heading levels in Advanced → structure detection.

Uploads run over HTTPS, files are processed in isolated containers, and both the source HTMLZ and the MOBI output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.

No. KaijuConverter does not strip digital rights management. DRM-free HTMLZ files — anything you authored yourself, public-domain classics, files from DRM-free retailers — convert without any restriction.

Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.

Yes. The cover is extracted from the HTMLZ and re-embedded in the MOBI at device-appropriate dimensions. You can also override it in Advanced by uploading a custom cover image alongside the book file.