In developmentThis tool is still in development. It needs a server component that is not switched on yet, so it will not convert files in your browser right now. The 58 browser tools work fully today — this one is still in development.
Deeply re-compress image-heavy PDFs for the smallest possible size. This uses a server-side pipeline that is only available when the optional backend is enabled.
Requires server
This tool needs a server — and isn't switched on
Unlike the 58 browser tools here, this one genuinely can't run in your browser. Office-format conversion, PDF encryption, and deep image compression need software that only exists server-side.
Uploads to server
How it works
- This is the tool our browser-based compressor honestly told you it couldn't be. Ghostscript re-encodes and downsamples the embedded images, which is where PDF bulk actually lives.
- On scan-heavy PDFs this approach can reduce size substantially, though the exact result depends on the source document and the final implementation, versus the ~5% a browser can manage. That difference is exactly why this one needs a server.
- Compression is lossy — higher settings visibly degrade images. Check the result before discarding your original.
- This tool uploads your file to a server — unlike every browser-based tool here. This conversion requires server-side processing and is not currently available on AllDays.Tools. When it becomes available, this page will explain exactly how files are handled. But if that tradeoff matters to you, use the client-side tools instead, where the file provably never leaves your device.
The story behind it
Compression is really several different problems
A PDF may contain already-compressed JPEG images, lossless images, fonts, duplicate resources and structural data. 'Deep' compression can therefore require different strategies for different contents.
The biggest reduction may come from images
Downsampling a large scanned image can save far more space than removing a little document metadata, but stronger image reduction can also reduce readability or visual quality.