The Best Free PDF Compressors in 2026

Almost every bloated PDF is bloated for the same reason: images. A scanned contract, a slide deck exported with full-resolution photos, a brochure with print-ready graphics. Compressing a PDF mostly means re-encoding those images at a lower resolution or quality, and the tools below differ in how much say they give you over that, and in where your document goes while they do it.

How we compared them

We checked each tool against its own published documentation and pricing in October 2026, and say so where a vendor does not publish a limit. Our own compressor is listed last, with what it cannot do; we tested it on PDFs with photos, a text-only PDF, and in both of its modes.

The short answer

1. PDF24: best free option overall

PDF24 is funded by advertising and states that its web tools have no limits and need no registration. Its compressor is also the most configurable free web tool we found. You set the resolution in DPI and the image quality as a percentage, can convert everything to greyscale, and can strip metadata, annotations and attachments. There is a lossless mode for when you only want the easy savings.

Web files are processed on PDF24’s servers in Germany and deleted after an hour. On Windows, the free PDF24 Creator app does the same work offline, with no restrictions even for commercial use. It does not run on Mac or Linux.

2. Ghostscript: best if you are comfortable with a terminal

Ghostscript is the engine many other tools are built on, and it is free and runs on your own machine. One command compresses a PDF:

gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -o smaller.pdf original.pdf

The preset decides the result. /screen downsamples colour images to 72 DPI, which gives the smallest files and can make scans hard to read. /ebook uses 150 DPI and is the right choice for most documents read on a screen. /printer and /prepress keep 300 DPI and do not downsample. Every setting can also be overridden individually, so it is also the most precise tool here.

3. Preview: built into every Mac, with a catch

On a Mac, open the PDF in Preview, choose File, Export, and pick the Quartz Filter called Reduce File Size. Nothing is uploaded and nothing needs installing. The catch is that the filter offers no settings and is aggressive: Apple itself warns the result may be lower quality than the original, and blurry output is a common complaint. It is fine for a quick email attachment and a poor choice for anything with small print or detailed images.

4. Sejda: the most control on the web

Sejda’s free compressor lets you choose image quality and an exact resolution, from 72 up to 720 PPI, plus greyscale conversion. That makes it very good for scanned documents. The free plan allows 3 tasks an hour, files up to 50 MB and documents up to 200 pages, one file at a time. Uploaded files are deleted after two hours, and the paid desktop version processes files locally.

5. iLovePDF: three simple levels

iLovePDF offers three choices, from Less compression to Extreme, and no finer control. The free plan handles up to 200 MB and two files per task. Files are deleted within two hours. Its strength is breadth: the same account and interface cover desktop apps for Windows and Mac and apps for iOS and Android, and Premium costs US$4 a month billed annually.

6. Adobe Acrobat online: large files, limited use

Adobe’s free compressor accepts files up to 2 GB, the largest of any tool here, with high, medium and low compression levels. Free use is limited without Adobe saying exactly how far, and finer settings are kept for paid Acrobat plans. Files are processed on Adobe’s servers and deleted unless you sign in to save them.

7. Smallpdf: fine for a one-off

Smallpdf’s free plan includes only its Basic compression level. Moderate and Strong are Pro features. Files are deleted an hour after processing, and Smallpdf describes the tool as built for image-heavy documents such as scans. Free use is subject to limits it does not publish.

8. PDFgear: free apps that work offline

PDFgear is free with no sign-up, watermark or ads. Its web tool handles up to 100 MB and runs on servers in the United States. Its desktop and mobile apps compress on your own device with no size limit, which is the version we would use. The site gives inconsistent answers about how long uploaded files are kept, which is another reason to prefer the apps.

9. Office’s “Minimum size” option: prevention

If the PDF has not been made yet, the cheapest compression is at the source. When saving a PDF from Excel, PowerPoint and other Office desktop apps on Windows, Microsoft offers a Minimum size (publishing online) option for when size matters more than print quality. It only works when creating the PDF, not on an existing one.

10. Stirling-PDF: self-hosted, for teams

Stirling-PDF is an open-core PDF toolkit you run on your own server or computer, typically with Docker, so documents never go to an outside service. Its compressor offers a quality level from 1 to 9 and, usefully, a desired file size, plus greyscale conversion. The free plan covers all its tools for up to five users. It is the right choice for an office that wants an internal PDF tool rather than staff uploading documents to websites.

11. qpdf: lossless restructuring

qpdf is a free command-line tool that restructures a PDF without touching image quality. Generating object streams usually makes files smaller, and it can recompress internal data losslessly. An optional image setting converts images to JPEG only where that is smaller. It does not downsample images, so its savings on scans are modest. Use it when you cannot accept any loss.

12. Foxit online: free, no settings

Foxit’s free online compressor needs no sign-up and accepts files up to 150 MB. Compression is automatic, with no level or resolution choice. Foxit says files are encrypted, deleted after processing, and not used for training. Its paid desktop editor, with a 14-day trial, adds compression levels and batch processing.

13. PDF Candy: two presets

PDF Candy offers Recommended and Maximum compression and nothing finer. Uploads are deleted within two hours. The free plan has hourly and file-size restrictions that it does not quantify. Paid plans start at $6 a month, or $99 for a lifetime licence with an offline Windows app.

14. NXPowerLite Desktop: bulk compression, paid

NXPowerLite is not free, at $59 for a perpetual licence after a 14-day trial, but it earns a place for one job: compressing thousands of files at once, locally, on Windows or Mac. It handles PowerPoint, Word, Excel and image files as well as PDFs, using saved profiles. Consider it if you are clearing out a shared drive rather than shrinking one attachment.

15. ConvertStuff: compresses in your browser

Our PDF compressor runs inside your browser with pdf.js and pdf-lib, so the PDF is never uploaded and there is no limit beyond your device’s memory. By default it re-encodes the photos inside the PDF as JPEG at the quality you pick, can shrink them to a maximum size in pixels, and leaves text, fonts and links untouched, so the text stays selectable. For scans, a second mode turns every page into a JPEG at 72 to 200 DPI. That shrinks harder, but the text becomes part of a picture and can no longer be selected or searched, and the page says so before you use it.

It has less control than PDF24 or Sejda: no greyscale conversion, no metadata stripping, and images are limited by pixel size rather than by DPI. Images in CMYK and other print colour spaces are left alone to avoid colour shifts, so print-ready PDFs shrink less. A PDF that is mostly text barely changes. If nothing smaller comes out, you get your original file back rather than a bigger one.

Which one to use

• A big scan for email: PDF24 or Sejda at 150 DPI, in greyscale if it is black text.
• Something confidential: Preview on a Mac, PDF24 Creator on Windows, Ghostscript, or our browser-based compressor if you cannot install anything.
• Dozens of files: Ghostscript in a loop, or PDF24 Creator.
• A file over 1 GB: Adobe Acrobat online, or a desktop tool.

Before you compress: is it the images?

If a PDF is large, look at what is in it. A 40-page report that is mostly text should be well under a megabyte. If it is 30 MB, there are full-resolution photos inside, and compression will cut it dramatically. A PDF that is already small and mostly text will barely change whatever you use, and the aggressive settings that force it smaller will make the images worse for a few kilobytes.

Merging is the other common cause. Combining PDFs can carry duplicated fonts and resources from every source file, so the result can be larger than the parts. Our merge tool runs in your browser, and compressing the merged file afterwards removes much of that overhead. For why PDFs hold what they hold, see what happens inside a PDF when you convert it.