Free Online PDF Compressor
Optimize internal document streams or downsample scanned pages directly in your browser.
Drag & drop your PDF file here, or browse files
Supports standard PDF documents up to 50MB
⚙️ Optimization Settings
1. Understanding PDF File Size and Overhead
PDF documents can grow significantly due to embedded resources. Common causes of large file sizes include high-resolution scanned pages, uncompressed object streams, redundant font subsets, and residual metadata from previous edits.
Depending on the internal composition of the document, optimization strategies differ. Clean text-and-vector PDFs benefit from object deflation, while scanned physical documents require raster downsampling to achieve significant size reduction.
2. Optimization Mode Comparison
Technical trade-offs between available in-browser compression modes:
| Mode | Primary Method | Text Selectability | Best Use Case |
|---|---|---|---|
| Balanced | Stream compression & orphan object cleanup | 100% Preserved (Vector typography) | Digital invoices, eBooks, typed reports |
| Extreme | Canvas page re-rendering & JPEG embedding | Converted to Bitmap Images | Multi-megabyte scanned paperwork & receipts |
3. Technical Limitations of Client-Side Processing
- Vector vs. Raster Trade-Off: In Extreme mode, pages are rendered into image canvases and re-saved as JPEG pages. This eliminates searchability and text highlighting in exchange for lower file sizes on scanned pages.
- Memory Bounds: Processing large documents (e.g., more than 50 pages in Extreme mode) relies on client device RAM. Very large files may cause browser tabs to reload.
- Protected PDFs: Encrypted or password-locked PDF files must be decrypted before client scripts can re-encode them.
4. Client-Side Execution & Privacy Terms
All parsing, object stream cleanup, and canvas rasterization execute locally within your browser sandbox. Your document content is not uploaded to our backend servers.
Standard analytics and third-party advertising scripts (such as Google AdSense) operate on this page and may collect anonymized telemetry according to our standard Privacy Policy.
5. Related Document Tools
6. Frequently Asked Questions (FAQ)
What is the difference between Balanced and Extreme compression?
Balanced mode cleans internal object streams, deflates uncompressed data, and keeps text selectable. Extreme mode rasterizes each page onto an image canvas, which drastically shrinks scanned pages but turns text into bitmap images.
Why didn't my text-heavy PDF shrink significantly?
Pure text PDFs contain minimal binary weight. Most PDF file size comes from high-resolution scanned images and embedded full-font families. Stream optimization will clean overhead, but massive reductions only occur on image-heavy documents.
Are my confidential PDF documents uploaded to external servers?
No. The optimization and rendering routines run locally in your web browser memory. Documents are not transferred to our servers.
Can I compress password-protected PDF files?
Encrypted or password-protected PDF documents must be unlocked before local browser scripts can parse or optimize their internal content streams.