Compress an EPUB
Drop in an EPUB and it re-encodes the images inside — covers, illustrations, embedded scans — while leaving the text, structure and metadata exactly as they were.
- Runs on your device
- No upload, no server
- No account, no sign-up
EPUB Reducer
Compress or Merge EPUB files. Images are converted to optimized JPEGs to reduce size.
Upload EPUB Files
Drag & drop your EPUBs here
Reduction Settings
Images are re-encoded to shrink them, which is lossy — keep your original if you need it. Everything runs in this browser tab; no file is uploaded.
It is almost always the images
The text in a novel-length EPUB is tiny — often under a megabyte. When an EPUB is large, it is because of embedded images stored at far higher resolution than any reader will display. Re-encoding those is where the size goes.
What is left alone
Chapter structure, table of contents, metadata and the text itself are untouched — they are copied through unchanged. Only the image files inside the archive are re-encoded, so the book opens and navigates exactly as before.
Nothing leaves your device
The EPUB is unpacked, processed and repacked inside your browser. No copy is uploaded, which matters for books you own but would rather not hand to a web service.
Questions
Will it break DRM-protected books?
It cannot open them at all. DRM-protected EPUBs are encrypted, so there is nothing to re-encode. This works on DRM-free files only.
Does the text get compressed too?
No. Text is copied through untouched — it is a negligible share of the file size and re-encoding it would risk breaking the book's structure for no gain.
Will my reader still open it?
Yes. The output is a standard EPUB with the same structure and metadata as the input; only the image files inside are smaller.
BiblioFuse reads CBZ, CBR, EPUB, PDF and TXT on iPhone, iPad, Mac, Android and Windows — and streams big libraries straight from your own machine.
See BiblioFuse Reader