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PDF Compress

Reduce your PDF's file size by removing metadata and compressing the document structure. Runs entirely in your browser — your file never leaves your device.

How this works: This tool re-serializes your PDF using object streams and removes metadata to reduce file overhead. It works best on PDFs with lots of metadata or redundant structure. It does not recompress embedded images — and if it can't make the file smaller, it keeps your original untouched.

Understanding the PDF Compress

This tool reduces a PDF's file size by streamlining its internal structure and stripping metadata, working entirely in your browser. It is best for documents bloated by redundant structure or heavy metadata rather than large embedded photos. If it cannot make the file smaller, it leaves your original untouched so you never download a worse copy. Useful when an email attachment limit or upload form rejects a PDF that is only slightly too big.

How it works

Using the pdf-lib library locally, the tool loads your PDF and rewrites it using object streams, a compact way of storing PDF objects, while clearing title, author, subject, and keyword metadata. The re-serialized bytes are measured against the original. Only if the new file is genuinely smaller is it offered for download; otherwise you keep the original and see a notice. Note that this approach does not recompress embedded images, which are the main weight in photo-heavy or scanned PDFs. Everything runs in your browser, so the document never leaves your device.

Savings (%) = ((Original Size − New Size) / Original Size) × 100

Worked example

A 480 KB PDF exported from a word processor often carries duplicated structure and metadata. After re-serialization with object streams, it might drop to 360 KB. Savings = ((480 − 360) / 480) × 100 = 25%, and the 360 KB file downloads. By contrast, a 5 MB scanned PDF made of full-page images may re-serialize to about 5 MB; since that is not smaller, the tool keeps your 5 MB original and explains that image recompression, which it does not perform, would be needed.

Tips & common mistakes

  • Best results come from text-based PDFs with bulky structure or metadata, not image-heavy scans.
  • For scanned or photo-heavy PDFs, lower the scan resolution or recompress images before exporting.
  • If you get a no-savings notice, the file is already well optimized; that is expected, not an error.
  • The tool removes document metadata (author, title), which also helps with privacy.
  • Encrypted PDFs may not process, so remove the password first if loading fails.

Related tools

PDF MergeCombine multiple PDF files into one, reordering pages before merging.PDF SplitExtract specific pages from a PDF or split it into individual files.JPG to PDF ConverterConvert JPG and PNG images into a single PDF, in order, in your browser.Word CounterCount words, characters, sentences, paragraphs, and reading time.

How to Compress a PDF

  1. 1Upload your PDF by clicking the upload area or dragging and dropping your file.
  2. 2Click Compress & Download. The optimized file downloads automatically.
  3. 3You will see a comparison of the original vs. new file size and the percentage saved.

Frequently Asked Questions

How does this PDF compressor work?

The tool re-serializes your PDF using object stream compression and strips metadata (author, creator, keywords). This reduces file overhead, though the effect varies by PDF. It does not recompress embedded images.

Why is my compressed file the same size or larger?

If the PDF is already well-optimized or was generated by a modern tool, there may be little overhead to remove. Image-heavy PDFs require image recompression (a server-side operation) to see significant size reductions.

Are my files uploaded to your servers?

No. All compression happens locally in your browser. Your file is never transmitted to any server.

What file sizes can this handle?

There is no hard limit. Very large files (50 MB+) may be slow depending on your device's memory and CPU.