Instructions & Help
Complete guide to all PDF Compresso features
Complete guide to all PDF Compresso features
PDF Compresso is a self-contained Windows desktop app with 18 PDF tools spread across three pages, plus a set of app-wide features (Pipeline, Recent Files, Light Mode) that tie them together. Everything runs locally on your machine, entirely in-app — there's no server to start, no Node.js to install, no external engine to configure, and no internet connection required after setup.
Your files never leave your computer. All processing happens locally, ensuring complete privacy and security.
Quick Links to Apps:
🏠 Main Tools 🛠️ PDF Tools 🔒 Convert & SecurityAccess these tools from the main PDF Compresso page.
Combine multiple PDF files and images into a single PDF document. Perfect for assembling reports, combining scanned documents, or creating photo albums.
Images are automatically scaled to fit standard page sizes while maintaining their aspect ratio. The order you arrange the files is the order they'll appear in the final PDF.
Reduce the file size of your PDF documents. Ideal for email attachments, web uploads, or saving storage space. Compress can process multiple files at once, shows you a live size estimate before you commit, and offers fine-grained controls beyond the three quality presets.
Actual reduction varies a lot by content: photo-heavy or scanned PDFs typically shrink the most (often 70%+ at Medium/High), while text-only documents with few or no images may see little to no size change, since Compress works by re-encoding embedded images rather than touching fonts or text.
Drop as many PDFs as you like at once — each is compressed in sequence with its own progress and result, and you can download files individually or all together as a zip.
As soon as you drop a file (or change any setting), Compress automatically shows an estimated Original / New / Saved size for the first file in the batch, so you can compare quality levels before running the real compression. If you drop more than one file, the preview is labeled with which file it's based on.
Compress runs entirely on your machine, in the app itself — there's no external tool to install or configure, and no internet connection needed.
Rearrange, rotate, and delete pages from your PDFs. You can even combine pages from multiple PDFs into a new arrangement.
Use "Reset" to undo all changes and restore the original page order. Deleted pages are only removed from the output—your original files remain unchanged.
Remove restrictions from PDF files, such as printing or copying limitations. Can also unlock password-protected PDFs if you know the password.
You must have legitimate access to the PDF files. This tool is intended for unlocking your own documents when you've forgotten restrictions you set, or for PDFs where you have permission to remove restrictions.
Add signatures, text, dates, and checkmarks to PDF documents. Perfect for signing contracts, filling forms, or annotating documents.
You can customize the signature color and line thickness when drawing. For typed signatures, try different fonts to find one that looks most like your natural handwriting.
View and edit a PDF's document properties, and export an archival PDF/A version for long-term storage or legal/records-retention requirements.
Converts your PDF to PDF/A-1b or PDF/A-2b, embedding the standard sRGB reference color profile and the output-intent structure required for archival compliance.
PDF/A export produces a structurally correct archival PDF (valid OutputIntent/ICC profile, correct XMP conformance metadata), but it isn't run through a full ISO 19005 conformance validator — for strict legal certification requirements, verify the output with a dedicated PDF/A validator too.
Access these tools from the PDF Tools page.
Extract specific pages from a PDF or split it into multiple separate files.
Rotate pages in your PDF by 90°, 180°, or 270°. Apply to all pages or select specific pages to rotate.
Add page numbers to your PDF documents with customizable position, format, and styling.
Add text or image watermarks to your PDF pages. Great for marking documents as confidential, draft, or adding your logo.
Use PNG images with transparency for best results with image watermarks. A 30-50% opacity usually works well for watermarks that are visible but don't obscure the content.
Flatten form fields, annotations, and layers into the PDF. This makes form data permanent and prevents further editing.
Attempts to recover a damaged or corrupted PDF by scanning the file for intact content and rebuilding it into a clean, valid file — even when the document's own table of contents (its cross-reference table) is missing or broken.
The panel checks whether your file already opens normally and tells you honestly: if it opens fine, repair can still fix subtle structural issues, but it may not be necessary; if it fails to open, repair is likely to help.
If a file is only partially recoverable, PDF Compresso labels the result as a partial recovery rather than claiming a clean success — check the recovered content carefully in that case.
Access these tools from the Convert & Security page.
Convert multiple images into a single PDF document. Each image becomes one page.
Export each page of a PDF as an image file. Useful for sharing on social media, presentations, or when you need image formats.
Add password protection to your PDF files. Set a password required to open the document and optionally a separate owner password for full access.
Don't forget your password! There is no way to recover a password-protected PDF if you lose the password. Store it securely.
Permanently remove sensitive information from PDF documents. Unlike simple black boxes, true redaction destroys the underlying content—it cannot be recovered.
PDF Compresso uses true redaction: pages with redactions are flattened to images with the black boxes burned in. The original text, images, or data under the redaction is completely destroyed and replaced with black pixels.
Redaction is permanent and irreversible. Always keep a backup of the original file. Once redactions are applied, the underlying content is completely destroyed and cannot be recovered by anyone, including forensic tools.
Pages without redactions retain their original quality (vector graphics, searchable text). Only pages with redactions are converted to images.
Pulls the original embedded images out of a PDF, rather than re-rendering each page as an image (that's what PDF to Images does).
JPEG-encoded images embedded in the PDF are extracted as byte-perfect .jpg files. Other encodings (e.g. images embedded as raw/PNG-style data) are honestly reported as "skipped — unsupported encoding" rather than risking a corrupted re-encode.
Fast, near-instant text extraction for PDFs that already have a real text layer (i.e. text you can already select and search). This is distinct from OCR, which is slower but works on scanned/image-only PDFs with no text layer at all.
If Extract Text comes back empty or garbled, your PDF likely has no real text layer (it's a scan or image) — use the OCR tool instead.
These features aren't tied to one specific tool — they work across all three pages.
Hand a file straight from one tool to another without manually downloading it and re-uploading it — even across the three different pages.
This is great for chaining tools — for example, compress a file, send it to the pipeline, then switch to Sign to add your signature to the already-compressed version.
PDF Compresso remembers PDFs you've opened from disk (drag-dropped or browsed to), so you can quickly reopen one without re-browsing to it — even after restarting the app.
Only files opened from a real location on disk are tracked — files received via the Pipeline or a launched-from-Explorer file don't create duplicate entries.
Switch the entire app between dark and light appearance. Click the moon/sun icon in the header on any page to toggle — your preference is remembered across all pages and survives restarting the app.
The installer adds a "Compress with PDF Compresso" entry to the right-click menu for any .pdf file in Windows Explorer — a fast path for the single most common task, without opening the app first.
This adds a right-click option alongside your existing default PDF app — it doesn't change what happens when you double-click a PDF.
No. PDF Compresso is a desktop app — all processing happens locally on your machine, in the app itself. There's no server, no cloud upload, no external engine, and no internet connection needed to use any tool.
There's no hard limit, but very large files (over 100MB) may be slow to process depending on your computer's memory and processing power. For best performance, we recommend files under 50MB. If you're working with very large files, consider splitting them first.
Compress works out of the box with no setup needed. If a particular file doesn't shrink much, it's usually because it's mostly text with few or no images — Compress reduces size by re-encoding embedded images, so text-only documents will see little change. Photo-heavy or scanned PDFs typically compress the most.
No. PDF encryption is designed to be secure. If you forget your password, there is no backdoor or recovery option. Always store your passwords securely, and consider using a password manager.
Yes. PDF Compresso uses true redaction technology. Pages with redactions are rendered to images with the black boxes drawn directly on top, then the original page content is replaced with this image. The underlying text or graphics are completely destroyed—not just hidden. This is the same method used by professional legal and government redaction tools.
PDF Compresso works best on modern browsers:
• Chrome (recommended) — version 90+
• Firefox — version 90+
• Edge — version 90+
• Safari — version 14+
Internet Explorer is not supported.
Yes, PDF Compresso is responsive and works on mobile devices. However, some features (like drawing signatures or organizing many pages) are easier to use on a desktop or laptop. For the best experience with complex tasks, we recommend using a computer.
Pages with redactions are converted to images to ensure the redacted content is truly destroyed. This means:
• Text on those pages is no longer searchable or selectable
• The visual quality is still high (rendered at 2x resolution)
• Pages without redactions remain unchanged (vector graphics, searchable text)
This trade-off is necessary for true security—simple black box overlays can be removed by anyone with a PDF editor.
No. PDF Compresso never modifies your original files. All operations create new files that you download separately. Your original documents remain exactly as they were.
It depends on the tool:
• Merge: Yes, add as many files as you want
• Compress: Yes, drop as many PDFs as you like — each is compressed in sequence
• Organize: Yes, combine pages from multiple PDFs
• Unlock: Yes, up to 5 files at once
• Image to PDF: Yes, add multiple images
• Other tools work with one file at a time
It hands a processed file straight to another tool without you having to download it and re-upload it yourself. Click "📤 Send to Pipeline" on any result, then switch to another tool (even on a different page) and click the "📎 Use it" hint that appears under its upload zone. See the Pipeline section above for details.
Yes. Click the 🕒 icon in the header to see PDFs you've recently opened from disk, and click any entry to reopen it into the right tool. This list survives restarting the app. See the Recent Files section above.
Yes. Right-click any .pdf file in Windows Explorer and choose "Compress with PDF Compresso." This adds a right-click option alongside your existing default PDF app — it doesn't change what happens when you double-click a PDF. See the Explorer Right-Click Integration section above.
Still have questions?
PDF Compresso is designed to be intuitive and easy to use. If you encounter any issues, try refreshing the page and starting over. Most problems are resolved by using a modern browser and ensuring your files aren't corrupted.