Compress PDF

Compress PDF reduces file size by downsampling embedded images, subsetting embedded fonts, and removing redundant internal structures. It targets the most common reason PDFs are large: high-resolution images scanned at 300 DPI or above that are embedded at full resolution even when the document will only ever be viewed on screen. The compression is lossless for text and vector content; only raster images are resampled, which is why text pages compress minimally while scan-heavy documents can shrink by 60–80%.

Compress PDF is designed for mobile users, customer support teams, and anyone working with attachment limits. It runs entirely in your browser — your files are never uploaded to any server.

Step 1: Add your file. Click the upload area above or drag and drop your pdf documents directly onto it. Step 2: Adjust settings if needed. Use the settings panel to configure options such as output quality, page range, or file naming. Step 3: Run the tool. Click the action button. For simple tasks this takes a few seconds; for larger files or complex operations like OCR it may take up to a minute. Step 4: Download your result. The output file downloads automatically. No email, no sign-up, no waiting room.

One important note: if you are processing confidential documents — financial statements, legal contracts, medical records, or identification — none of this data passes through any external server. The entire operation runs inside your browser, and the file is cleared from memory when you close the tab.

A 20 MB scanned invoice pack (300 DPI, 10 pages) typically compresses to 3–5 MB on Medium quality — 75–85% reduction. A 5 MB text-only report typically compresses to 4–4.5 MB — 10–15% reduction (text compresses poorly because it is already efficient). HMRC Self Assessment portal upload limit: 3 MB. UK Visas and Immigration portal: 6 MB per document. Most university application portals: 5–10 MB. Medium quality (150 DPI target for images) is the right preset for documents that will be read on screen. Low quality (72 DPI) is only appropriate for thumbnails or low-bandwidth previews.

If you are preparing files for a specific portal, check the upload limit before processing. Compress PDF is available immediately after this tool if you need to reduce file size for submission.

PDF/A files (long-term archival format) should not be compressed — the format standard requires specific embedded resources that compression may strip. Use the standard PDF output instead. PDFs with embedded video or audio are not compressed — only static page content is processed. A PDF that was already compressed by another tool may increase in size slightly if this tool's internal object model produces a larger output structure. If this happens, keep the original. High compression (72 DPI) applied to a document containing signature images will make signatures illegible. Use Medium or Low compression for signed documents.

When you use a typical online PDF tool, your document is uploaded to a company's server, processed there, and returned as a download. During that process, the company technically has access to your file. For sensitive files — payslips, ID documents, client contracts — that is a real privacy consideration.

PDF Genius Pro takes a different approach. Compress PDF runs entirely in your browser using standard web technology. Your file is read by your browser's JavaScript engine, processed locally, and saved to your downloads folder. At no point does the file travel to a server. This is why the tool continues working even if your internet connection drops mid-process — it does not need the internet to do its job once the page has loaded.

Take a moment to review the output before sending it on. The most important checks for compress pdf are: Open the compressed file and check that all text is still sharp and readable. Check any photos or diagrams at 100% zoom — there should be no visible blocking artefacts at Medium quality. Verify the output file size meets the target portal's upload limit before attempting to upload. Confirm no pages are blank or distorted — rare but can occur if the source contains unusual transparency layers.

If the result does not look right, you can re-run the tool with different settings at no cost. Adjusting quality, page range, or file order are quick fixes. The tool is designed to support iteration.

Compress PDF works on mobile browsers including Safari on iPhone and iPad, and Chrome on Android. The upload area supports tap-to-browse on mobile devices, and drag-and-drop works on tablets. Processing is handled by your device's own processor, so performance depends on your device's speed and available memory.

For very large files (over 30 MB), a desktop browser on a computer with more RAM will give faster and more reliable results. For typical document tasks, mobile processing works well.