Compress a PDF without uploading it
Pick a file, choose how much quality you are willing to trade, and get a smaller PDF. The whole process runs inside this browser tab.
Drop your PDF here
or pick a file from your device
- Drop a PDF onto the page, or press Select PDF. CLEKARA reads it and reports the page count, PDF version, content type and how many images it found.
- Choose a profile. Smart is the default: it compresses a few representative pages with every profile, measures the real size and the visual difference, and picks the least aggressive one that still gives a worthwhile reduction.
- Press Compress PDF. When it finishes, the result is opened and checked before it is offered for download.
It measures instead of guessing
Compression runs on Ghostscript compiled to WebAssembly. Rather than applying a fixed recipe, Smart mode first compresses a small sample of pages with each profile, compares the resulting sizes against a reference render, and scores the visual difference of each candidate against the original.
A profile is only accepted if it saves a meaningful amount and stays above a quality threshold that depends on the type of document — a scan tolerates more loss than a page of text. If nothing achieves a useful reduction, CLEKARA keeps your original file and says so instead of handing you something slightly larger.
What it will not do
Digitally signed PDFs, XFA forms, owner-restricted files and PDF portfolios are blocked on purpose: rewriting them would break the signature, drop the form or silently remove the restrictions.
Documents with fillable forms, embedded JavaScript, attachments, layers or tagged accessibility structure are allowed, but you have to confirm first, because those elements are lost when the file is rewritten.
A PDF that is already optimised, or that is mostly text with few images, has little left to compress. 250 MB is the practical ceiling for browser processing, and phones will manage less.
Frequently asked questions
Are my files uploaded anywhere?
No. The PDF is read into memory and processed by code running in this tab. It is never sent to a CLEKARA server.
Which profile should I pick?
Smart, unless you have a reason not to. It tests the real document instead of assuming. Use High quality for anything that will be printed, and Maximum only for on-screen reading.
Why did my PDF barely get smaller?
Most of the savings come from images. A text-only PDF, or one that has already been compressed, has very little left to remove. CLEKARA will tell you when that happens rather than inventing a result.
Can I set a target size?
You can enter an optional target in MB. CLEKARA will aim for it, and if it cannot be reached without damaging the document it will give you the smallest valid result it found and say that the target was missed.
Why does this page take a moment the first time?
The compression engine is a WebAssembly build of around 16 MB. It is downloaded only on this page, and only once — the other five tools never touch it.