PDF Compressor
Free online pdf compressor. Process data instantly in your browser. No upload, no signup, fully private.
Local processingWhat is PDF Compressor?
A PDF compressor reduces a PDF file's size by re-encoding its internal streams, removing redundant objects, and downsampling embedded images. PDFs often carry uncompressed or redundantly encoded content — fonts, images, and metadata — that can be losslessly or near-losslessly shrunk. The tool processes the file in the browser so sensitive documents never leave the user's device.
How It Works
The PDF is parsed client-side into its object structure (cross-reference table, stream objects, fonts, images). Compression strategies include re-flating uncompressed streams with DEFLATE, deduplicating identical objects, stripping unused metadata and embedded fonts, and downsampling high-resolution images. The optimized object graph is re-serialized into a new PDF. The user compares original and compressed sizes before downloading.
Common Use Cases
- Shrinking scanned documents — compress image-heavy PDFs for email attachment
- Reducing web-hosted PDF sizes — speed up downloads for online brochures and reports
- Optimizing archival storage — compress long-term document stores to save disk space
- Meeting upload limits — fit a large PDF under a portal's file-size cap
Technical Details
Engine: client-side JavaScript PDF library (WASM-accelerated). Compression: DEFLATE (FlateDecode) for streams, image downsampling for embedded raster content. Lossless for text and vector content; image downsampling is lossy. Encryption is preserved or removed per user choice. Output fidelity depends on the source — already-optimized PDFs see little further reduction.
How to Use
Enter your input above. The result updates automatically. Use the copy button to copy the result.
Privacy
All processing happens in your browser. Your data is never uploaded to any server.
FAQ
Is this PDF Compressor free?
Yes, completely free. No signup required.
Does this tool upload my data?
No. All processing happens locally in your browser. Your data never leaves your device.
What compression levels are available?
The tool offers lossless compression (re-flating uncompressed streams, removing redundant objects and metadata) and near-lossless compression (downsampling high-resolution embedded images). Text and vector content remain lossless; image downsampling is the only lossy step and can be adjusted or disabled.