Compress PDF
Reduce the size of a PDF without turning it into pictures. Structure optimisation is lossless; image optimisation re-encodes embedded photographs while leaving text untouched.
How to use Compress PDF
- Select a PDF.
- Start with Structure only — it is lossless and instant.
- If that is not enough, switch to Image optimisation and lower the quality or the maximum image size.
- Compare the before and after figures, then download if you are happy with the result.
About this tool
There are two honest ways to make a PDF smaller in a browser, and this tool does both. Structure optimisation rewrites the file’s internal bookkeeping using compressed object streams and drops redundant metadata. It changes nothing you can see, and on documents exported by older software it can still remove a useful chunk. On a file that was already written efficiently it will save almost nothing.
Image optimisation is where real savings usually come from, because in most large PDFs the bulk is embedded photographs. Each embedded JPEG is decoded, scaled down if it exceeds the pixel limit you set, re-encoded at your chosen quality and swapped back in. Text, fonts and vector graphics are never touched, so the document stays selectable, searchable and sharp.
What this tool deliberately does not do is rasterise. Rendering every page to an image is how some compressors hit dramatic numbers, and it destroys selectable text, accessibility and print quality in the process. It also will not pretend: if the output is not meaningfully smaller than the input, it says so and offers you the original file instead of a re-saved copy of the same thing.
Frequently asked questions
Why did my PDF barely shrink?
Almost certainly because it was already optimised, or because its size comes from something other than images — embedded fonts, vector artwork, or a very large number of pages. A text-only report exported from Word is already close to as small as it reasonably gets. The tool reports the real figure rather than inventing a reduction.
Will the text still be selectable afterwards?
Yes, in both modes. Text, fonts and vector content are copied through untouched. Only embedded raster images are re-encoded, and only in image-optimisation mode.
Which images get optimised?
Embedded JPEG images, which are what scanners and cameras produce and what dominates the size of most large PDFs. Images stored in other encodings, in CMYK colour, or as transparency masks are skipped rather than risked, and the tool tells you how many it processed and how many it left alone.
Is it safe to send the compressed file instead of the original?
For everyday sharing, yes. For print production, archival or anything legal, keep the original: image optimisation is lossy by definition, and a 150 DPI photograph that looks fine on screen may be visibly soft in print. Compare the preview figures before deciding.