Best Free PDF Compressors in 2026 — I Tested 5 Tools With 30 Documents

ILovePDF (iLovePDF S.L., Barcelona) is one of the oldest online PDF tool suites, launched in 2010. Files are uploaded to their servers, compressed server-side using one of three presets (Extreme, Recommended, Less Compression), and returned as downloads. The interface shows an estimated output size before you compress, which helps you pick the right tradeoff between quality and file size.

Compression ratios were solid across all 30 test documents — averaging 55-75% reduction depending on the preset. Text remained sharp at all levels. Image quality on the "Recommended" preset was good; "Extreme" showed visible JPEG artifacts on photos but kept text readable. Forms and annotations survived compression intact.

The catch: free users get 1 task per hour. If you have multiple documents to compress before an email deadline, that's a real problem. The 100MB file size limit also blocked 3 of our larger scanned documents. For paid users at $7/month, these limits disappear.

SmallPDF (SmallPDF GmbH, Zurich) is known for clean, minimal design. Upload a PDF, choose Basic or Strong compression, and download the result. The interface is deliberately simple — fewer options than ILovePDF, but less overwhelming for casual users. All processing happens on their servers in Switzerland.

Compression was consistent across our test documents. The "Basic" preset averaged 50-60% reduction with good quality. "Strong" pushed to 65-70% but introduced visible JPEG artifacts on photos. Text remained sharp at both levels. Forms were mostly preserved, though 2 of our test documents lost interactive form field styling after strong compression.

Free tier allows 2 tasks per day. Pro costs $12/month — the most expensive in our test. The 50MB file size limit on free is the lowest, which blocked 5 of our test documents.

Adobe Acrobat's "Optimize PDF" feature lets you compress with fine-grained control over image quality, font subsetting, and object compression. The online version handles basic compression; the desktop app offers advanced controls including per-image DPI settings. Adobe invented the PDF format, and their compression preserves every element while achieving strong ratios. If PDF fidelity matters above all else, Adobe is the reference implementation.

Compression quality was excellent — the best element preservation in our test. Every form field, signature, annotation, and embedded font survived compression intact. Ratios averaged 60-80% reduction, matching MiOffice AI. The online tool's three presets (High, Medium, Low quality) give good control. The desktop app's "Advanced Optimization" is the most powerful compression configurator available anywhere.

The problem: there is no free tier for compression. The online tool requires an Adobe account and teases you with a 7-day trial, then it's $19.99/month. For compressing PDFs, that's steep when free alternatives exist.

PDF24 (Geek Software GmbH, Germany) is a completely free, ad-supported PDF tool suite with 30+ tools. Files are uploaded to their German servers, compressed using selectable quality presets, and returned. No accounts, no usage limits, no watermarks. The trade-off is ads — banner ads between operations and on the results page. The interface is functional but dated compared to ILovePDF or SmallPDF.

Basic compression worked reliably across all documents. Ratios averaged 50-70% reduction. Speed was competitive at 2-5 seconds. However, form field preservation was inconsistent — interactive form elements lost functionality in 4 of our 30 test documents. Image quality on higher compression was noticeably worse than ILovePDF or Adobe.

The big advantage: it's genuinely free with no daily limits. No signup, no payment wall. If you can tolerate ads and don't need perfect form preservation, PDF24 gets the job done.