About this tool
Almost everyone who compresses a PDF is doing it for the same reason: a portal has refused the upload and printed a number. So this tool takes the number rather than offering low, medium and high, and works towards it.
What it does under the hood is worth stating plainly, because it is the whole trade-off. Each page is rendered to a canvas, encoded as a JPEG, and written into a fresh PDF at the original paper size. A ladder of quality settings is tried in order (full resolution at high quality first, then lower quality, then progressively smaller) and the first result that fits under your limit is the one you get. Quality is spent before resolution, because at a given file size a slightly soft page at full resolution is more readable than a sharp one at half.
The cost of that approach is that the output is a picture of your document. It looks right on screen, it prints right, and it is exactly the same size of paper. But the text is no longer text: you cannot select it, search it, or have a screen reader read it, and any link, bookmark, form field or digital signature is gone. For a scanned certificate going into an application form, none of that matters. For a contract you are archiving, all of it does: keep the original and compress a copy.
The honest failure is also worth knowing about. If a target cannot be reached without turning the pages to mush, the tool gives you the smallest readable version and tells you it missed. And if your PDF is already smaller than anything re-rendering would produce (common with short text documents) it declines rather than handing back a bigger file with worse type.
The entire process runs on your device. A document you are compressing for a government portal never leaves your phone, which is the correct arrangement for a file that probably has your name, address and photograph in it.
How to use this tool
- Choose your PDF. Up to 40 pages and 50 MB. It is read straight into the browser: the file is not uploaded anywhere.
- Type the limit your form asks for. The box starts at 500 KB. Portals commonly ask for 200, 500 or 1024 KB; use whatever number is on the form in front of you.
- Run it and wait a moment. Each page is re-rendered, then a series of quality settings is tried in turn until one comes in under your limit. A long document on an older phone will take a little while.
- Read the result before you upload. You get the old size, the new size and the percentage saved. Open the PDF and check the pages are still legible: especially small print and stamps.
What this tool does not do
- The output is a rasterised PDF. Text is no longer selectable, searchable or readable by a screen reader.
- Links, bookmarks, annotations, form fields and attachments are all discarded.
- Digital signatures are destroyed. Do not use it on a signed document.
- Up to 40 pages at a time, and 50 MB in.
- Encrypted or password-protected PDFs cannot be opened.
- It cannot always reach a small target. When it cannot, it says so rather than handing you something unreadable.
Common questions
Why is the text no longer selectable afterwards?
Because compression in a browser means re-rendering. Each page is drawn onto a canvas, encoded as a JPEG and placed into a new PDF at the same paper size. The result looks like the document and prints like the document, but it is a picture of it: so text cannot be selected, copied or searched, and a screen reader cannot read it. For a form upload this is almost always fine. For an archive copy, keep the original.
Why not compress it properly, without rasterising?
Doing it properly means re-running the original compressors on each embedded object: the image streams, the font subsets, the object tables. That needs a full PDF engine, which in a browser means several megabytes of WebAssembly downloaded before anything happens. Re-rendering gets most of the benefit for a fraction of the cost, provided you know what you are giving up. Now you do.
It says the PDF is already smaller than anything it can produce.
That happens with documents that are already tightly compressed, and with short text-only PDFs, where the fonts take less space than a picture of the same page would. There is genuinely nothing to gain, so nothing is offered.
It could not reach my limit.
Then it hands back the smallest result that is still readable rather than one that is not. A twenty-page scanned document will not become 100 KB at any quality worth having. Split the PDF and upload the pages separately, or ask whether the portal will take a larger file.
Are my scanned photographs going to look worse?
Yes, and how much worse depends on how far the target is from the original. The tool spends image quality before it reduces resolution, because text stays legible longer that way. Always open the result and look at it before you upload: a certificate number that has turned to mush is worse than a file that was slightly too big.
Does it keep bookmarks, links, and form fields?
No. Everything interactive is lost: links, bookmarks, annotations, filled form fields, attachments and any digital signature. Page size and page order are preserved; nothing else is.
Is a digitally signed document still valid afterwards?
No. Re-rendering invalidates any digital signature, permanently. Never compress a digitally signed document you are required to submit as signed.