PDF Compress
Reduce the file size of your PDF documents by stripping metadata and optimizing internal structures.
Reduce the file size of your PDF documents with customizable compression levels. Choose 100% private browser compression or deep stream optimization on our Cloud Engine.
Drop a PDF file here to compress
Supports single PDF files up to 300MB (or click to browse)
1. Compression Level
2. Processing Engine
Best choice for 95% of documents. Significantly reduces file size for fast email and web sharing while maintaining sharp image & text quality.
How do I use PDF Compress?
Drop your PDF file into the compressor or click "Load Sample Data" to test with a sample document.
Choose a compression preset (`Extreme / 72 DPI`, `Recommended / 144 DPI`, or `Lossless Structure Optimization`).
Compare the before/after byte savings percentage and download your compressed PDF.
What features does PDF Compress offer?
Smart multi-level compression presets: Recommended (150 DPI), Low (Print quality), and Extreme (Email ready)
Selective image stream downsampling that retains 100% sharp vector typography and line drawings
Removal of duplicate font descriptors, unused color profiles, and redundant uncompressed metadata objects
100% client-side in-browser WebAssembly execution or 300MB high-capacity Cloud Engine
Instant real-time file size savings calculator and interactive percentage progress tracking
Zero file data retention policy guarantees confidential financial and legal files never leave your memory
PDF Stream Filters, DPI Downsampling & Byte Reduction Benchmarks
Compares lossless object-stream cleanup (`FlateDecode`) against lossy raster downsampling (`DCTDecode` JPEG / `JPXDecode`).
| Compression Preset | Target Image DPI | Stream Encoding Filter | Typical Size Reduction | Best Use Case |
|---|---|---|---|---|
| Lossless / Structural | Native (Unchanged) | FlateDecode (zlib) + Orphan Object Purge | 5% – 20% | Vector CAD drawings, contracts,LaTeX papers |
| Balanced (Recommended) | 144 – 150 DPI | DCTDecode (JPEG Q=75) + Flate | 45% – 70% | Email attachments, reports, slide decks |
| Extreme (Web / Portal) | 72 – 96 DPI | DCTDecode (JPEG Q=55) + Metadata Strip | 70% – 90% | Government portal uploads with strict 2MB limits |
Frequently Asked Questions about PDF Compress
Why did my text-only PDF barely shrink under Lossless compression?
Text and vector paths inside modern PDFs are already compressed with `FlateDecode` (`zlib` DEFLATE). Significant size reductions (`50%–85%`) occur primarily when embedded high-resolution raster images (`300+ DPI`) are downsampled to `144 DPI` or `72 DPI`.
What is the difference between `FlateDecode` and `DCTDecode` inside a PDF?
`FlateDecode` is lossless LZ77+Huffman compression used for text streams, fonts, and vector paths. `DCTDecode` is Discrete Cosine Transform (JPEG) lossy compression applied specifically to continuous-tone `/Image` XObjects.
Does rasterizing/downsampling a PDF affect selectable text?
Structural optimization preserves 100% of selectable text and vector fonts, whereas full-page canvas rasterization flattens pages into compressed JPEG/WebP streams to guarantee maximum file size reduction for scanned documents.
How does stripping `/Metadata` and incremental-update (`xref`) history save space?
PDF editors often append changes as incremental updates at the end of the file, leaving deleted images and XMP metadata blocks orphaned in the byte stream. Rebuilding a clean single-pass `xref` table purges all dead objects.
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