Compress PDF — Reduce PDF File Size
Compress your PDF files to reduce file size. Choose between the Condense algorithm (recommended, preserves forms and links) or the Standard algorithm, plus 4 compression levels. Optionally remove metadata. Batch upload supported — files compress automatically. All processing stays in your browser.
Key Features
Advanced Compression
Compress PDF files using CoherentPDF's advanced compression engine. Uncompressed streams are compressed with Flate, and the document structure is optimized for smaller file sizes.
Four Compression Levels
Choose from Low (smallest file, maximum compression), Medium (recommended balance), High (better quality), or Maximum (best quality, minimal compression).
Batch Compression
Upload multiple PDF files at once — they compress automatically. Each result shows the original vs compressed size and percentage saved in the scrollable list.
100% Private & Secure
All compression happens locally in your browser using CoherentPDF WASM. Your PDF files never leave your device — no uploads to any server, complete privacy.
No Installation Required
No software to download or install. The compression engine runs in your browser — works on any device with a modern browser.
About This PDF Compressor
Our PDF Compressor offers two compression algorithms running entirely in your browser. The Condense algorithm (default) uses PyMuPDF to clean and optimize the PDF structure through garbage collection, deduplication, and stream compression — it preserves interactivity such as form fields, links, and bookmarks while achieving good size reductions. The Standard algorithm uses CoherentPDF, a professional PDF library compiled to WebAssembly, to compress uncompressed streams with Flate and optimize the document structure. Both algorithms offer four compression levels: Low applies the most aggressive compression; Medium offers a recommended balance of size reduction and quality; High performs lighter compression for better visual quality; Maximum preserves the original quality with minimal changes. You can also choose to remove document metadata for additional savings and privacy. Each compressed file shows its original and compressed size along with the percentage saved. All processing stays local in your browser — no data is ever uploaded.
How to Compress PDF — Step by Step
Compressing a PDF with our tool is simple:
Upload Your PDFs
Drag and drop one or more PDF files onto the upload area. Files begin compressing automatically — no button to click.
Choose Algorithm & Level
Select the compression algorithm (Condense for preserving forms and links, or Standard) and a compression level: Low for the smallest file, Medium for a recommended balance, High for better quality, or Maximum for best quality. Optionally toggle Remove Metadata.
Download Results
Each compressed file appears in the results list showing original size, compressed size, and percentage saved. Download individually or use Download All for a ZIP archive.
Important Notes
Compression results vary depending on the PDF content. Files with many images or uncompressed streams show the most size reduction. Already-optimized PDFs may show minimal savings. The Condense algorithm (default) preserves interactivity such as form fields, links, and bookmarks while the Standard algorithm focuses on stream and structure optimization. The Low and Medium levels apply stronger compression which may slightly affect image quality. Encrypted PDFs cannot be compressed — please decrypt them first. Remove Metadata strips document information such as title, author, and producer.