PDF Compressor — Free, Private, Browser-Based
Optimize the file structure of a PDF in your browser. You can remove document metadata and flatten form fields. Scanned images are not downsampled, and the output may be unchanged or larger.
How to optimize a PDF in your browser
- Choose the options. Turn on Remove Metadata and/or Flatten Forms before adding files. Flattened form fields are no longer editable afterwards.
- Add your PDFs. Drop one or more PDF files into the upload area, or click to browse.
- Wait for local processing. Each file is re-saved in your browser with optimized object streams. Nothing is uploaded.
- Compare and download. Check each output size against the original, then download the results individually. If an optimized file came out larger, keep the original.
Use Cases
Frequently Asked Questions
Are my PDFs uploaded to a server?
No. Processing runs entirely in your browser. Your files are never uploaded.
Does it downsample images inside my PDF?
No. The tool has no quality presets and does not re-encode or downsample images — scanned pages keep their embedded images exactly as they are.
What does flattening form fields do?
Flattening turns the current form field values into page content — the values stay in the document, but the fields are no longer editable.
How much smaller will the PDF get?
It depends entirely on the original file structure. Structural re-saving helps some files; others come out the same size or slightly larger. Savings are not guaranteed.
Is there a file size or page limit?
There is no fixed limit. Practical limits depend on the memory your browser has available, and very large PDFs may fail to process.
Optimization options and file structure
The tool can clear common document properties and flatten form fields, then re-save structural objects. It does not re-encode embedded images.
| Option | What it does | What to watch out for |
|---|---|---|
| Remove Metadata | Clears common document properties such as title, author and creator | Not a redaction tool — page content, annotations and embedded files are left alone |
| Flatten Forms | Turns current field values into page content | The flattened fields are no longer editable |
| Object Streams | Structural optimization applied when the file is re-saved | No image downsampling — large embedded images and scans stay as they are |