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PDF Compressor

Shrink PDF files losslessly in your browser: recompress streams, merge duplicate objects and strip metadata. Batch processing, no upload.

Your inputs and files stay in your browser

Drag and drop PDF files here

or choose a file from your device

On this page

Reduce PDF size losslessly in the browser: streams are recompressed, duplicate objects merged and metadata removed, while text, images and layout stay exactly the same. Files never leave your device.

Detailed Functionality

Each PDF is optimized without re-rendering. Flate and LZW streams are recompressed at the highest zlib level (kept only when smaller), uncompressed streams get compressed, identical objects are stored once, unused objects are dropped and the cross-reference table becomes a compressed stream (PDF 1.5). Embedded JPEG images keep their pixels; only their metadata segments are stripped.

The document info (author, producer, dates), XMP metadata and page thumbnails are removed; links, bookmarks, layers and accessibility tags (structure tree, marked content, document language) are kept. Images are not downsampled, so a scanned or photo-heavy PDF may shrink only a little, while files with uncompressed or poorly compressed streams shrink the most. The result can even be slightly larger — then Saved shows a negative percentage.

You can add several PDFs at once. They are processed one after another in a Web Worker with a progress bar, and Cancel stops immediately. A damaged file or one that needs a password to open gets an error on its row while the rest continue. Results download as compressed_<name>.pdf.

Practical Examples

Uncompressed export: a 2,500-page test PDF with uncompressed page streams goes from 5.44 MB to 685.91 KB (Saved 88%).

Small document: a one-page 729 B PDF becomes 658 B (Saved 10%) — gains come from metadata and the compressed cross-reference table.

Batch with a locked file: drop report.pdf, locked.pdf and slides.pdf; the locked one shows “locked.pdf: the PDF is password-protected and can't be processed.” and the other two get their Download buttons.

Already optimized: a PDF saved by a modern editor may show Saved 0% or a negative value — keep the original.

How to Use This Tool

  1. Add PDF files

    Click Choose file or drop one or more PDFs onto Drag and drop PDF files here. Each file appears in the list with its Original Size.

  2. Compress

    Click Compress PDFs. The progress bar shows the current file; Cancel stops the batch.

  3. Check the savings

    Every row shows Compressed Size and a Saved N% badge, or an error for damaged and password-protected files.

  4. Download

    Click Download on a row to save compressed_<name>.pdf.

Tips and Best Practices

  • Expect the biggest savings on PDFs with uncompressed or weakly compressed streams; scans and photo-heavy files barely change because images are not downsampled.
  • Tagged (accessible) PDFs stay tagged: the structure tree, marked content and document language are not changed.
  • PDFs that open without a password but have editing restrictions are processed; files with an open password are rejected.
  • Remove a row with the × button before compressing if you added a file by mistake.
  • Already compressed files are skipped when you click Compress PDFs again, so you can add more files to the same batch.