Compress PDF — Shrink File Size in Your Browser
Compress PDF file size in your browser and see before/after bytes—nothing is uploaded to a server. Steps: open a PDF, pick Medium or Low quality, compress, then download. Example: a two-page sample with embedded images drops from about 180 KB to roughly 90 KB on Medium. Text-only PDFs may barely shrink. Encrypted files fail with a clear error. Differs from Organize (reorder pages) and Merge (combine files).
How it works
Choose one PDF, pick Medium or Low, click Compress, then Download. Each page is rendered and saved as JPEG inside a new PDF. Stats show original size, new size, and percent change. Libraries load on first use.
Rules you should expect
How raster JPEG presets, before/after stats, privacy, and failure cases work when you compress a PDF locally.
- Engine: pdf.js draws each page to canvas; the PDF library embeds JPEG pages into a new PDF—no server round-trip for your file.
- Presets: Medium (scale 1.2, JPEG ~72%) vs Low (scale 1.0, JPEG ~55%). Lower preset = smaller but softer output.
- Stats: shows original bytes, compressed bytes, and percent change. Saves under 5% trigger a “barely smaller” note.
- Limits: encrypted or corrupt PDFs fail with a readable error; very large files (>~25 MB) may be slow; text-only PDFs may not shrink much.
Example
Sample loads a two-page PDF with gradient blocks and embedded JPEG pages, runs Medium compression, shows before/after size with percent saved, and enables Download for compressed.pdf.
Good fits
- Office: shrink a scan packet before email attachment limits.
- Students: reduce a photo-heavy assignment PDF for upload forms.
- Site owners: trim a marketing PDF for faster sharing—when raster quality is acceptable.
Frequently asked questions
Is my PDF uploaded?
No. pdf.js and the PDF library run in your tab (libraries may load from a CDN). Your PDF is not uploaded to our servers.
Why did my file barely get smaller?
This tool rasterizes each page to JPEG and rebuilds a PDF. Text-heavy or already-optimized files may shrink little or grow slightly. It is not the same as server-side recompression of embedded streams.
Is this cloud re-encoding?
No. Pages are redrawn as images in the browser. There is no cloud re-encoding step—your bytes never leave the device.
What about encrypted PDFs?
Password-protected PDFs usually fail to open here. Remove the password first, then compress.
Which quality preset should I use?
Medium keeps more detail (scale 1.2, JPEG ~72%). Low is smaller but softer (scale 1.0, JPEG ~55%). Pick based on email limits vs readability.
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Questions or feedback
Something unclear, broken, or missing? Draft a message below — we read every note about these tools.