PDF & Files
Free PDF Compressor
Free to useNo sign-up requiredNo watermarkRuns in your browser
This free PDF compressor reduces file size by re-encoding the photographs inside your document. Your text, fonts and vector graphics are left exactly as they are, so the result is still selectable, searchable and sharp at any zoom level.
That is a deliberate and unusual choice. Most browser-based PDF compressors work by rendering every page to a JPEG and rebuilding the file from those pictures. It produces impressive-looking percentages on image documents, but it destroys selectable text and frequently makes text-only PDFs several times *larger*.
How this tool works
Choose your PDF
Read straight from your device - there is no upload.
Pick how hard to compress
Light keeps the best quality, Balanced suits most documents, Strong gives the smallest file with visible softening of photographs.
Compress
Each embedded image is re-encoded in turn, with progress shown.
Check the result and download
You are told the before and after sizes and how many images were changed - and if the file could not be made smaller, you get the original back untouched.
How it works
The document is opened and every embedded JPEG image is found. Each is decoded, redrawn at the chosen quality - and optionally at a reduced resolution - then written back into the file in place of the original.
Page content streams, fonts, text and vector graphics are never touched. This is what keeps the text selectable and is the whole point of the approach.
The rebuilt file also uses object streams, a lossless PDF feature that reduces structural overhead slightly.
Images stored with encodings other than plain JPEG are deliberately skipped rather than converted, because a wrong reconstruction would corrupt the picture. That means a PDF full of PNG-style images may compress little.
If the result would be larger than what you gave us, the original is returned unchanged. A compressor that hands back a bigger file has failed, and pretending otherwise helps nobody.
What kind of PDF actually shrinks
| Scanned document or photo-heavy report | Large saving, often 60-85% |
|---|---|
| Mixed text and photographs | Good saving, typically 40-80% |
| Presentation exported to PDF | Moderate, depends on the images |
| Text-only document or invoice | Very little - there is nothing to compress |
| Already-compressed PDF | Little or nothing; the original is returned |
Why we refuse to rasterise
Flattening every page to an image is the quick way to make a PDF look smaller, and it is what most free browser tools do. The costs are severe: the text stops being text, so it can no longer be searched, selected, copied or read by a screen reader; the file no longer scales cleanly when zoomed or printed; and for a document that is mostly text, the output is routinely many times bigger than the input, because a compact page of glyphs becomes a full-page bitmap.
We measured exactly that on a competing implementation: a 3 KB text PDF came back at 120 KB. Our approach leaves that same file essentially unchanged, which is the honest outcome - there was nothing there to compress.
Getting a bigger saving
- Try Strong, which also caps the longest edge of each image at 1400 pixels - usually plenty for on-screen reading.
- If the PDF came from images you still have, resize those first with the free image resizer and rebuild the PDF with JPG to PDF.
- Remove pages you do not need with the free PDF splitter before compressing.
- For a text-only document that is somehow enormous, the size is usually embedded fonts rather than images, and there is little a browser tool can safely do about that.
Worked examples
A scanned contract
Balanced typically halves the file or better, and the scan remains perfectly readable.
A photo-heavy report for email
Strong compression usually brings a document under a 10 MB attachment limit.
A text invoice
Comes back almost unchanged, with the tool telling you so rather than inflating it to look busy.
Frequently asked questions
Is this PDF compressor free?
Yes - free, no sign-up, no watermark and no limit on file size or how often you use it.
Are my files uploaded to a server?
No. Your files never leave your device. The file is opened and processed by your browser on your own machine, so nothing is transmitted to VSThiran and no copy of your document is ever stored on a server.
Can I compress a PDF without uploading it?
Yes. The whole job runs in your browser, so the document never leaves your device. That matters for the files people most often need to shrink - scanned contracts, passports and medical records.
How do I reduce a PDF to send by email?
Choose Balanced first and check the resulting size against your limit, which is usually 10 MB or 25 MB. If it is still too large, try Strong. A document that is mostly text will not shrink much, because there are no photographs in it to compress.
Will my text still be selectable after compressing?
Yes. Text, fonts and vector graphics are never altered - only embedded photographs are re-encoded. This is the main way this tool differs from most free PDF compressors, which flatten pages into images and destroy the text.
Why did my PDF barely get smaller?
Because it is mostly text. There is very little to compress in a text document, and the honest answer is to say so rather than rasterise the pages to manufacture a percentage. Compression savings come from photographs.
Why was my file returned unchanged?
Because compressing it would have made it larger. That happens with PDFs that are already well optimised. Handing back a bigger file would be worse than doing nothing.
Does it reduce image quality?
Yes, that is where the saving comes from. Light is visually near-identical, Balanced is a sensible compromise, and Strong noticeably softens photographs. Text is unaffected at every setting.
Can it compress a password-protected PDF?
No. Encrypted files cannot be opened without the password. Remove the protection first.
Guides for this tool
Why is my PDF so large?
Two ten-page PDFs can differ in size by a hundred times. Here is what actually makes a PDF large, and how to shrink one without losing quality.
Make a PDF smaller without losing quality
PDF too large to email or upload? Compress it directly in your browser with VSThiran - no signup or software install. Choose a compression level and download the smaller file.
What is a PDF file?
A PDF (Portable Document Format) is a file that looks the same on any device, printer or screen. Here is what that means in practice, and when to use one.
How to convert a PDF into an editable Word document
Need to edit a PDF's actual text? Convert it to Word in your browser with VSThiran - tables, images and headings carry across, and it opens directly in Word, Google Docs or LibreOffice.