How to compress a PDF
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Contents
To compress a PDF, open the Compress PDF tool, add your file, and download the lossless-optimized copy it produces right in your browser. Alongside that copy, the tool shows you a size breakdown so you can see exactly what is inflating the file — before you decide whether the optional deep image compression step is worth it.
What sets this approach apart is that it keeps two very different kinds of compression explicitly separate. The analysis and the lossless repack run entirely in your browser, so on that path your PDF stays on your device from start to finish. Deep image compression — the step that downsamples images in image-heavy files — is optional and clearly labeled, and it runs on a secure, auto-deleting server. The page checks that a server is available before anything leaves your device.
There is no account to create: add a PDF, read the breakdown, and save the result.
Step by step
- 1Open the Compress PDF tool.
- 2Add your PDF. The analysis runs privately, right in your browser — the file stays on your device while it is inspected.
- 3Review the size breakdown to see exactly what is inflating your PDF.
- 4Download the lossless-optimized copy. The repack runs entirely in your browser, and because it is lossless, the document's content is left as it was.
- 5For image-heavy files, choose the deep image compression step. It is optional and clearly labeled: your PDF is uploaded to a secure, auto-deleting server that downsamples the images.
- 6Before anything leaves your device, the page checks that a server is available — the deep step starts only after that check passes.
- 7Download the compressed result. The download link stops working after 60 minutes, and stored copies are erased by a daily storage rule.
Lossless repack vs. deep image compression
The lossless structural repack always runs in your browser. It rewrites the file's internal structure without touching the content, so it is the safe default: run it on any PDF, and if the result is small enough, you are done. The breakdown comes first, so you can see what is inflating the PDF before deciding whether the lossless pass alone will get you where you need to be.
Deep image compression is the second path, and it exists for image-heavy files. It needs a native engine, so it runs as an optional, clearly labeled secure-server step rather than in the browser: your PDF is uploaded to our server, images are downsampled, and you download a smaller PDF. Nothing routes you there silently — you choose the step yourself, and the page confirms a server is available before anything leaves your device.
Where your file is processed
Compress PDF is a hybrid tool, and the two paths have different privacy stories — both stated plainly. The size analysis and the lossless repack happen on your device: for that path, your PDF never leaves your browser. The optional deep image compression step is different: there, your file is uploaded to a secure server, and inputs are wiped when the job finishes. The download link stops working after 60 minutes, and stored copies are erased by a daily storage rule.
Because the availability check runs first, nothing is sent to a server that is not there to receive it.
When compression is not the job
Optimize PDF for Web is often mistaken for compression, and it is not: it linearizes the file so a viewer that loads a PDF in pieces can show the first page while the rest downloads. It is not meant to reduce size: the whole file is rewritten, so its size can change in either direction. Use it when the goal is a faster first page on the web, and Compress PDF when the goal is a lighter file.
Grayscale PDF converts a PDF to black and white for printing, right in your browser. Every page becomes a grayscale image, so text is no longer selectable or searchable — a trade worth knowing before you reach for it to save space.
What you get, and the limits
Both paths produce a PDF. The lossless copy is a repack of the same content; the deep path returns a PDF whose images have been downsampled to save space. The size breakdown you reviewed at the start is your guide: it shows exactly what is inflating the file, so you can judge whether the in-browser pass is enough or the file is image-heavy enough to justify the deep step. The per-file cap is 100 MB.
Common questions
Does compressing a PDF reduce its quality?
Not on the default path. The lossless repack restructures the file without altering its content — that is what lossless means here. Deep image compression does change images: it downsamples them to save more space, which is why it is a separate, clearly labeled optional step rather than part of the default pass.
Is my PDF uploaded when I compress it?
Not for the analysis or the lossless repack — both run in your browser, and on that path the file stays on your device. The exception is deep image compression. An optional, clearly labeled step uploads the file to a secure server — only when you start it, and only after the page confirms a server is available.
How large can my PDF be?
Up to 100 MB per file.
What happens to my file after deep image compression runs?
The job runs on a secure server, and inputs are wiped when the job finishes. The download link stops working after 60 minutes, and stored copies are erased by a daily storage rule.
Will a smaller PDF also open faster on a website?
Size is only part of it. If the PDF will be read in a browser, run Optimize PDF for Web on the compressed copy: it linearizes the file with qpdf on a secure server, so the first page can render while the rest still downloads, and the input is deleted after the job. Linearizing reorders the file for streaming; it is not a compression step, and the size can move in either direction, so compare the result with the copy Compress PDF gave you.
Do I need an account to compress a PDF?
No account is needed. Open the tool, add your PDF, review the breakdown, and save the result.