Compress PDF
Shrink scanned and image-heavy PDFs at a high-detail default. The tool checks every page first and, by default, leaves the original bytes unchanged when it finds selectable text or form fields.
What this tool is for
Scanned and image-heavy PDFs are often large because each page carries a high-resolution image: scanned pages, photographs, screenshots, exported design files, or product catalogs. This tool targets that case. A PDF can also be heavy for other reasons — embedded fonts, vector artwork, attachments, or duplicated objects — and raster compression will not reduce all of those. Before rasterizing anything, the tool inspects every page for selectable text and form widgets. With preservation enabled, finding either keeps the source PDF byte-for-byte instead of rebuilding it.
Image-only PDFs can be re-rendered and encoded as high-quality JPEG pages to reduce their size. Results vary with the source, so compare the output with the original before using it for a submission or archive.
How to compress a PDF
Drop in your PDF, leave Preserve selectable text and form fields checked, and click Compress PDF. The status first reports its page-by-page inspection. If protected document content is found, the download is the unchanged original. For image-only scans, Image quality controls JPEG detail and Resolution sets the nominal raster density; the default is about 216 DPI at 95% JPEG quality. Grayscale can reduce some scan sizes when color is unnecessary.
How your file is processed
PDF Compress uses pdf.js (loaded from a CDN) to inspect text, annotations, and page visuals in your browser. Protected documents are returned from the original byte buffer. Image-only documents can then be rendered locally and rebuilt with jsPDF, which also loads from a CDN.
Quality and honest limitations
Rasterization turns a page into pixels. It can work well for scans and photos, but it would flatten selectable text, hyperlinks, bookmarks, and interactive fields. That is why preservation is enabled by default: detected text or form widgets cause the original PDF to be used as the result with no raster compression. If you deliberately turn preservation off, those document features can be flattened. Hidden OCR text can also trigger preservation, which is the safer outcome for a searchable scan.
Common problems and fixes
The result is unchanged. The status will identify whether selectable text or form fields caused preservation; unchanged output is intentional. An image-only scan is still too large. Lower the JPEG quality or resolution, or enable Grayscale. Raster text looks soft. Use High or Maximum detail and keep quality near the default. A large PDF runs out of memory. Higher DPI creates larger page canvases, so try a desktop or a lower setting. Nothing happens. Confirm the file is a valid PDF and that the rendering libraries were allowed to load.
Frequently asked questions
What kind of PDFs does this compress best?
Scanned documents and image-heavy PDFs, which are usually the large ones. The tool re-renders each page as an image and re-encodes it at your chosen quality, so photo and scan content shrinks a lot. Pure text PDFs are already small and may not benefit.
Are my PDF files uploaded to a server?
No. The PDF is read, rendered, and rebuilt in your browser where supported using local libraries. The file is not uploaded to our servers for routine operations.
Why did my text PDF get larger or look softer?
This tool rasterizes pages, meaning sharp vector text becomes an image. For text-only PDFs that are already compact, that can increase size or soften text. Use it for scans and image-heavy PDFs; keep text PDFs as they are.
Related tools and guides
PDF to JPG · Image to PDF · Compress Image · All tools · How to compress images without ruining quality · When to turn images into PDF