Gulag Cleaner not working? What to check and how to clean your PDF anyway

Searching for “gulag cleaner not working” is practically a ritual at the end of every term: you have twenty Wuolah PDFs to clean, the site won't load or hands back a strange file, and the exam is tomorrow. Before you give up and delete pages by hand, run through this list. Nearly every time the problem is the file, the browser or the site you're using, and it takes a minute to fix.

First: there are two sites with the same name

Gulag Cleaner started as an open-source project with its own site, gulagcleaner.com. This page, gulagcleaner.pro, is an independent web version built on the same engine, released under the GPL-3 licence, and is not affiliated with the original. Both clean Wuolah and StuDocu PDFs. If one won't load or fails on your file, try the other: they are different sites on different servers, and they rarely go down at the same time.

The seven most common causes and how to fix them

1. The page won't load

Check your connection and reload the tab. If you use a strict content blocker, a VPN or a filtered campus network, switch them off for a moment or open a private window without extensions: some of them block the scripts that make the cleaner run. If the original site is down, open the gulagcleaner.pro cleaner.

2. The “Choose PDF” button does nothing

It's almost always the browser. Try an up-to-date Chrome, Firefox, Edge or Safari, or a private window. On a phone, the PDF has to be downloaded to the device: a document opened inside the Wuolah app isn't enough, you need the file in your downloads folder. The step-by-step is in Gulag Cleaner on mobile.

3. The PDF comes out exactly as it went in

If the removed-pages count is zero, the engine found no ads to remove. That happens with PDFs that were already clean, with documents scanned or generated by the author, and with files that don't come from Wuolah or StuDocu. For those two platforms the engine extracts the original page embedded inside each ad wrapper; for everything else it applies a generic method that only removes full-page ads and banners. The details are in How it works.

4. It hands your original back “untouched”

That's not a bug, it's the safety net. gulagcleaner.pro runs the engine in two modes, counts the pages of each result and discards any that ends up with no pages or removes more than 80% of the document. If neither passes, you get your original file back so you are never left without your notes. It usually happens with new Wuolah templates the engine doesn't recognise yet. In that case, report it on the project's repository.

5. Error while processing the file

A password-protected PDF, a damaged one, or a file that isn't really a PDF (a renamed image, say) causes a read error. Open it in any viewer first: if it won't open there either, the file is the problem. Download it again from the platform and retry.

6. Very large files, or a phone short on memory

There is no fixed size limit: the ceiling is your browser's memory. A course pack of hundreds of pages runs fine on any laptop; an old phone with many open tabs may run out. Close tabs, or clean that file from a computer.

7. An old browser

The engine is compiled to WebAssembly and needs a browser from the last three years. Update Chrome, Firefox, Edge or Safari and try again.

Cleaning the PDF on gulagcleaner.pro in three steps

1. Open the cleaner in any modern browser.
2. Drop the PDF on the page or tap “Choose PDF”.
3. Check the preview of the first pages and the removed-pages count, then click “Download clean PDF”. The file is saved with the .clean.pdf suffix.

Everything happens in your browser. The PDF is never uploaded, so there is no queue, no account and no daily limit.

If nothing works: the honest alternatives

• The command line. The original project publishes gulagcleaner on PyPI. With Python installed, pip install gulagcleaner and gulagcleaner notes.pdf clean single files or whole folders. We compare it with the web version in CLI vs web version.
• A PDF editor. In Wuolah each real page sits inside an ad page, so deleting pages by hand doesn't always work and cropping is slow. Fine for one file, not for twenty.
• The platform's own ad-free download. It's paid, but it exists. The options are in Wuolah without ads.

Still failing on one specific file? That's the best way to improve the engine: open an issue with the sample PDF.