A job applicant uploads their CV as a PDF to a recruitment portal. The portal rejects it: "File size exceeds 5MB limit." The PDF is 18MB because it was exported from a design tool with high-resolution images. A doctor sends a patient's scanned records as an email attachment and it bounces back. A consultant's 40-page illustrated proposal is too large to attach to any email client with standard limits. All three problems are the same: a PDF that is larger than the situation allows.
Compressing a PDF is not the same as degrading it. Done at the right level, the text stays sharp, the layout is unchanged, and images remain fully readable. This tool handles that balance through four compression levels with an estimated output size shown before you commit to the download. The whole process runs in your browser via PDF-Lib and the Canvas API. Your file is never uploaded to any server.
How It Works
- Upload your PDF by dragging it onto the upload area or clicking to browse. The tool reads the file structure and displays the original file size immediately. An expected result panel updates as you select compression settings, showing the estimated output size and savings percentage before any processing begins.
- Choose a compression level from four presets. Screen keeps the best quality with a 10 to 20 percent reduction, suitable for on-screen reading where visual fidelity matters most. eBook delivers a balanced result at 30 to 50 percent smaller, covering most email and upload use cases. Printer targets 50 to 65 percent reduction with acceptable quality for print-only use. Minimum compresses as aggressively as possible at 65 to 80 percent smaller. For more control, expand Advanced Options to set image quality (85% to 35%), maximum image DPI (150 DPI for web, 96 or 72 for screen or minimum), color space (keep original or convert to grayscale), object stream compression, and optional removal of metadata, annotations, bookmarks, and form fields.
- Compress and download by clicking Compress PDF. The Canvas API recompresses embedded image streams at your selected quality and DPI. PDF-Lib optimizes the document structure, object streams, and any toggled removals. The process runs through Loading, Analysing, Optimizing, Recompressing, and Done. Download the compressed file immediately.
Compatibility & Support
Supported Input and Output
- Input: Any standard PDF (text-based, scanned, image-heavy, form-based, multi-page)
- Output: Compressed PDF with reduced file size at the selected quality level
- Compression levels: Screen (10-20%), eBook (30-50%), Printer (50-65%), Minimum (65-80%)
- Advanced controls: Image quality (85%, 72%, 55%, 35%), Max DPI (original, 150, 96, 72), Grayscale conversion, Object stream compression, Remove metadata, Remove annotations, Remove bookmarks, Flatten form fields
What Compression Does Not Help With
PDFs that contain only text and vector graphics with no embedded images will see minimal size reduction from image-focused compression. For those documents, the Object Streams and Remove Metadata options address structural bloat. Very small PDFs (under 200KB) may see little meaningful reduction regardless of settings because there is minimal redundancy in the file to remove.
File Size Limits
All processing runs in-browser via PDF-Lib and Canvas API, so no server-imposed file size cap applies. Larger files take more processing time since each embedded image is individually decoded and re-encoded during the compression pass. The pre-compression size estimate updates with settings changes and gives a reliable indicator of the output before you run the full process.
Who Should Use This Tool?
- Students: A student submitting a project PDF with embedded diagrams and screenshots to a university portal with a 10MB file limit can use the eBook level to bring a 25MB export well under the threshold without visibly degrading any of the chart or screenshot content.
- Freelancers & Designers: A brand designer delivering a 40-page illustrated proposal can compress the print-quality export to an email-ready version using the eBook level with 150 DPI, producing a file that shares cleanly without requiring the client to download from a file-sharing service.
- Office Professionals: A medical practice administrator sending scanned patient referral documents via email can use the Printer level alongside the Remove Metadata toggle to produce a compact, privacy-conscious file under the email server attachment cap.
- Developers: A developer optimizing PDFs for a web application where page load time matters can use the Minimum compression level with 96 DPI and grayscale conversion on archived document PDFs, reducing storage costs and bandwidth without needing a server-side processing library.
Key Features
Here's what separates this tool from generic alternatives:
No Server Upload
PDF-Lib and the Canvas API compress the file entirely in your browser. Medical records, legal documents, and confidential business reports never transfer to any external server at any point.
Pre-Compression Size Estimate
The expected result panel shows the estimated output size and percentage savings before you click Compress. Adjust settings until the estimate hits your target file size, then run the actual process once.
Four Preset Levels
Screen, eBook, Printer, and Minimum cover the range from near-lossless quality preservation to maximum size reduction. Each preset has a clear expected reduction range displayed alongside it.
Grayscale Conversion
The Color Space option converts all color images to grayscale during compression. Combined with DPI reduction, this often produces 40 to 60 percent additional size reduction beyond image quality alone, useful for archiving and printing documents where color is not needed.
Metadata and Annotation Removal
Toggle removal of metadata (author, title, editor history), annotations, comments, and bookmarks independently. Each removes overhead from the file and also addresses privacy concerns before sharing documents externally.
Full Advanced Control
Image quality percentage, maximum DPI, object stream compression, and flatten form fields give precise control over exactly what gets compressed and how, rather than forcing a single black-box quality setting.
Why This Tool Beats the Alternatives
- No account, email, or signup required at any point.
- No watermarks added to the compressed PDF output.
- No server upload; sensitive documents stay in the browser throughout the entire compression process.
- Pre-compression size estimate lets you see expected results before downloading, which most tools do not offer.
- Grayscale conversion, metadata removal, and per-component advanced controls in one free tool; these are typically paid or Pro-only features elsewhere.
- No daily limits or file count restrictions on the free tier.
Pro Tips
- Check the size estimate at each compression level before running the full process. The difference between eBook and Printer is often only a few percent in output size but can be a visible step down in image quality. If eBook already hits your target size, there is no reason to use Printer or Minimum.
- For archive-quality compression of scanned documents where color is irrelevant (contracts, legal filings, handwritten notes), combine the Printer level with Grayscale conversion. This combination consistently produces the largest size reduction on scanned PDFs while keeping text sharp and fully readable at the output quality settings.
- If compression alone is not reducing the file enough, combine it with a prior downsampling pass. Use the Downsample Images in PDF tool to reduce image DPI first, then run the compressed output through this compressor for a second pass targeting object streams and metadata. Two targeted passes almost always produce better results than one aggressive compression at maximum settings.
Upload your PDF, check the size estimate at your preferred compression level, and download a smaller file in seconds. If the document also has wide margins adding bulk, the Trim PDF Whitespace tool removes unnecessary margin space before compression, reducing the content area the compressor has to process.