Does PDF Compressor work in the browser?
Yes. The PDF is read and processed locally with browser-compatible PDF libraries; no external conversion API is used.
PDF Compressor
Reduce PDF file size with realistic browser-based compression.
1
Upload
2
Configure
3
Convert
4
Download
Reduce PDF file size with realistic browser-based compression.
High Quality preserves the PDF structure. Balanced and Maximum can rasterize pages for meaningful visual compression when that creates a smaller file.
Choose a PDF to compress
Drag and drop one PDF here, or press Enter to browse your device.
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Tool guide
Free Online PDF Compressor
Reduce PDF size directly in your browser with realistic quality controls. Formatza compares valid compression candidates and keeps the smallest result, while clearly explaining when an already optimized PDF has little room to shrink.
Steps
How it works
- Upload one PDF and review its original size, page count, and first-page preview.
- Choose High Quality, Balanced, or Maximum Compression with the quality slider.
- Compare the original first page with a debounced visual quality estimate.
- Compress the full document sequentially in your browser.
- Review the compressed size and percentage saved, then download the finished PDF.
Highlights
Key features
- Provides realistic High Quality, Balanced, and Maximum Compression presets.
- Shows original size, compressed size, and percentage reduction.
- Updates a first-page quality preview after compression settings change.
- Uses structure-preserving optimization for High Quality mode.
- Tests visual page compression for lower-quality presets and only keeps it when the result is smaller.
- Processes the document locally with browser-compatible PDF libraries.
Use cases
Common uses
- Make an image-heavy PDF smaller before sharing it.
- Reduce the size of scanned documents and visual reports.
- Compare first-page quality before compressing a complete PDF.
- Optimize a PDF for browser viewing or email attachment limits.
Notes
Limitations to know
- PDFs that already contain optimized images and compressed objects may show little or no size reduction.
- Balanced and Maximum Compression may flatten pages into images, so selectable text, links, forms, annotations, and other interactive features may not be retained.
- High Quality preserves the PDF structure but usually provides less compression.
- Large, complex, encrypted, malformed, or unsupported PDFs may exceed browser memory or fail to process.
- The first-page preview estimates visual quality; final size depends on all pages and assets in the document.
FAQ
6 answersFrequently asked questions
Which compression preset should I choose?
Balanced is the recommended starting point for image-heavy PDFs. Choose High Quality when selectable text and interactive document features matter most, or Maximum Compression when the smallest visual PDF is the priority.
Will the compressed PDF keep selectable text?
High Quality mode preserves the document structure. Balanced and Maximum may flatten pages into images when that produces the smallest valid result, so text may no longer be selectable.
Why did my PDF size stay the same?
The source may already be optimized. Formatza does not replace it with a larger generated file or claim savings that were not achieved.
Can I compress a password-protected PDF?
A locked PDF must be unlocked before browser-based compression can read and rewrite it.
Are page size, order, and orientation preserved?
Page order and visual dimensions are preserved. Visual compression renders each page in its displayed orientation, while High Quality keeps the original document structure.