Compress PDF

Apparatus optimizes the internal structure of your PDF - it packs objects into compressed streams, strips metadata (author, title, keywords), and at higher levels flattens form fields. This is most effective on text-heavy documents, forms, and files with large metadata blocks. Image-heavy PDFs like scanned documents will see smaller reductions since images are not re-encoded.

Yes. Most online compressors upload your files to a remote server, which is a concern for confidential documents. Apparatus runs entirely in your browser - your PDFs never leave your device, and no data is transmitted.

No. Low and Medium compression only change how data is stored internally - all visible content is identical. High compression also flattens form fields (making them non-editable) but does not alter text or images.

It depends on the original file. PDFs with large metadata blocks, uncompressed object streams, or fillable forms see the biggest reductions (up to 30-40%). Image-heavy PDFs like scanned documents will see minimal reduction since this tool optimizes structure, not image data.

Yes. Add as many PDF files as you like. They will all be compressed with the same settings and can be downloaded individually or as a ZIP archive.

Low: minimal changes, preserves all metadata and form fields. Medium: strips metadata and uses compressed object streams for a good balance. High: maximum structural compression including form flattening.