Browser-based
Your file is processed locally without waiting for a server conversion queue.
No upload required
Files stay in your browser, which is ideal for private drafts and personal libraries.
Free ebook tool
Merge and split ebook files without signup, credits, watermarks, or installation.
How to compress an EPUB
Upload your EPUB
Select the ebook you want to shrink. It is processed entirely in your browser.
Choose a preset
Pick an e-reader preset, or enter a target file size and we'll converge on it automatically.
Download the result
Preview the savings per image and download the compressed EPUB.
FAQ
Will compression reduce quality?
The lossless preset keeps every image untouched. Lossy presets re-optimize images to match your reading screen — in normal reading the difference is barely noticeable.
Are my files uploaded?
No. Compression runs entirely in your browser; the file never leaves your device.
Why does my book barely shrink?
Books that are mostly text are already compact. The savings come from images, so illustrated books and comics benefit the most.
How accurate is the estimated size?
It's an approximation based on your book's image share. The final size shown after compression is exact — and the target-size preset verifies the result for you.