Compress PDF
Shrink a heavy PDF down to a smaller file, without it ever leaving your device.
Compressed PDF ready.
How it works
This tool rebuilds your PDF page by page. Each page is rendered to an image at a controlled resolution using Mozilla's PDF.js, re-encoded as a JPEG at the compression level you pick, and placed back into a fresh PDF with pdf-lib. Because photos and scans are usually what make a PDF heavy, re-encoding them at a lower quality is the most effective way to bring the file size down. Everything runs inside your browser tab, so the document is never uploaded to a server.
How to compress a PDF
Drop your file in, pick a level (start with Medium if unsure), press Compress, and compare the before/after sizes shown in the result. If the file is still too big, run it again at Strong; if the text looks fuzzy on screen, go back and try Light. You can compress the same original as many times as you like — nothing is overwritten.
A concrete example
Many email providers and job portals cap attachments at 5 or 10 MB. A 30 MB scanned contract won't get through. Compressed at Medium, that scan typically lands between 3 and 8 MB — small enough to send, readable enough to sign and archive. The exact result depends on your document, which is why the tool shows you the measured size instead of promising a fixed percentage.
Choosing a compression level
Light keeps images close to their original sharpness and is a safe choice when the PDF will be printed or read closely. Medium is a good all-round setting for sharing by email or uploading to a portal where size limits apply. Strong pushes the file as small as possible and works well for text-heavy scans that only need to stay legible on screen. After compressing, the tool shows you the before and after size so you can decide whether to try a different level.
When compression helps most
PDFs built from scanned pages, phone photos, or high-resolution screenshots shrink dramatically. A PDF that is already mostly selectable text with few images will compress less, because there is little redundant image data to remove. If your goal is to keep the original text layer perfectly intact, compression is not the right tool — it flattens each page to an image.
The trade-off, honestly stated
This method trades the text layer for size: after compression, pages are images, so text is no longer selectable or searchable. That's usually fine for documents that are read, printed, signed or archived. If you need to keep searching and copying text, keep the original and only compress the copy you send. For PDFs that barely shrink — already-light, mostly vector text — there is little to gain from any image-based compressor.
Frequently asked questions
Will the text still be selectable afterwards?
No. Compression flattens each page into an image, so the searchable text layer is removed. If you need selectable text, keep the original file.
Why did my file barely get smaller?
Your PDF was probably already lightweight or made mostly of vector text. Compression mainly saves space on image-heavy documents.
Is my document uploaded anywhere?
No. The whole process runs locally in your browser, and the file never leaves your device.
Which level should I choose for printing?
Light. Printing magnifies compression artifacts, so keep quality as high as the size limit allows.
Can I compress several PDFs at once?
This tool handles one file per run. For batch image compression we have a separate Compress Image tool.
Is compressing the same as optimizing?
Not exactly. Optimizers only reorganize the existing file's internals and save modest space; this tool genuinely re-encodes the heavy image content, which is where the big reductions come from.