How much smaller will my PDF get?

It depends on how much of the file is images. Scans and photo-heavy documents often shrink a lot, while a text-only PDF may barely change. After compressing, the tool shows the size before and after, and with Light, Balanced or Strong, if no saving was possible it returns your original file unchanged and says so.

Will the text still be selectable and searchable?

Yes, with Light, Balanced or Strong. Those levels only touch the images, so text, links and form fields stay exactly as they were. Flatten to images is the exception: it renders every page to a picture, so text can no longer be selected, searched or read by a screen reader.

What is the difference between the compression levels?

Each level shrinks embedded JPEG images to a maximum size and re-encodes them at a set quality: Light keeps images up to 2400 px on the longest edge at 85 percent quality, Balanced 1600 px at 68 percent, and Strong 1100 px at 50 percent. Flatten to images renders each page at 120 dpi as a JPEG at 60 percent quality and rebuilds the PDF from those pictures.

Can I compress a PDF to a specific size, such as 200 KB?

Yes. Type the size under Fit under a size. The tool tries the Light, Balanced, Strong and Very strong image settings, then, if Flatten pages to images if that is the only way to fit is ticked, renders the pages as pictures at 110 dpi down to 50 dpi, and stops at the first result under the limit. The file is saved as name-under-200KB.pdf. If the limit cannot be met, you get the smallest version it reached and a note saying so.

Is my file uploaded to a server?

No. The images are decoded, resized and re-encoded on your own device using your browser's built-in JPEG support. Nothing is sent to FreeAIPDF or anyone else.

Why did my file not shrink at all?

The standard levels only re-encode JPEG images in RGB or grayscale. Images stored in lossless formats, CMYK images, transparency masks and very small images are skipped, and a PDF that has already been optimized has little left to give. For a scanned document, Flatten to images usually gives a much larger saving.

Does it work on scanned PDFs?

Yes. If each scanned page is stored as a JPEG, Light, Balanced and Strong re-encode it and keep any existing text layer. Scans stored in other formats, such as black-and-white CCITT or JBIG2 images, are skipped by those levels. Flatten to images works on any scan because it renders the page, but it discards the text layer, so if you need the scan to stay searchable, run OCR PDF on the result afterwards.

Compress PDF Online Free – Pick a Level or a Target Size

Direct Answer & Privacy Assurance

Compress PDF: Compress PDF makes a PDF smaller by re-encoding the JPEG images inside it at a lower quality and resolution, then rewriting the file so unused objects and duplicated structure are dropped. With the three standard levels, text, links and form fields are left as they are, so the result still reads, searches and prints like the original. A fourth level, Flatten to images, trades that for the largest saving. FreeAIPDF runs 100% locally in your web browser using WebAssembly. Your files never leave your device, guaranteeing absolute confidentiality, zero subscriptions, and no file size paywalls.

Compress PDF makes a PDF smaller by re-encoding the JPEG images inside it at a lower quality and resolution, then rewriting the file so unused objects and duplicated structure are dropped. With the three standard levels, text, links and form fields are left as they are, so the result still reads, searches and prints like the original. A fourth level, Flatten to images, trades that for the largest saving.

If a form or portal sets a limit, type it in the Fit under a size box, or tap 50 KB, 100 KB, 200 KB, 500 KB or 1 MB. The tool then tries stronger settings one after another, from re-encoding the images to, if you allow it, turning the pages into pictures at lower resolutions, and stops at the first one that fits. If it cannot get under the limit, you get the smallest version it reached and a note saying so.

The whole job runs in your browser with JavaScript. The file is never uploaded, so there is no transfer to wait for and nothing stays behind when you close the tab. Files up to 100 MB each, twenty at a time. When you compress several at once, each comes back as its own PDF and you can download them together as a ZIP.

How much you save depends on what is in the file. A scanned document or a photo-heavy brochure can shrink a great deal. A PDF that is mostly text has almost nothing to give up, and images stored in lossless formats are left untouched by the three standard levels. With those levels, if the rewritten file would not be smaller, the tool hands back your original unchanged and tells you so.

How to use Compress PDF

1Click Select files, or drop your PDFs onto the page. Use Add more files to include others.
2To fit a size limit, type it under Fit under a size or tap a quick size. Otherwise leave the box empty and choose a compression level: Light, Balanced, Strong, or Flatten to images. Balanced is selected by default.
3Click Compress, or Fit under 200 KB (the button names the size you set) when a size is set. The progress bar names each image as it is recompressed, or each page as it is rendered when pages are flattened.
4Read the note showing the size before and after, then click Download to save the compressed PDF, or Download all as ZIP if you compressed several.

Compress PDF Specifications & Privacy Overview

Core technical parameters and security disclosures for Compress PDF.

Processing Architecture: 100% client-side, runs in your browser
Data Transmission: 0 bytes uploaded; the file never leaves your device
Usage & Cost: 100% Free; unlimited daily document processing
Account Requirement: Zero sign-up, no email, no payment details
File Capacity: Up to 100 MB per file
Platform Compatibility: Windows, macOS, Linux, iOS (iPhone/iPad), Android

Why FreeAIPDF vs Cloud PDF Converters

Security & Capability	FreeAIPDF (Client-Side)	Other Online Converters
Document Privacy	✓ 100% Local (0 bytes uploaded)	✗ Uploaded to external servers
Pricing & Limits	✓ Completely Free & Unlimited	✗ Daily caps & paid tiers
User Accounts	✓ No signup or email required	✗ Forces registration
Execution Speed	✓ Instant client-side engine	✗ Network upload & queue delay

Technical Architecture & Verifiable Security

Verifiable client-side sandbox execution parameters for enterprise, compliance, and privacy verification:

Execution Runtime100% In-Browser WebAssembly (Wasm) + V8 JavaScript Engine

Network Transmission0 bytes uploaded. Disconnect WiFi to verify 100% offline execution

Data Retention PolicyEphemeral RAM execution. 0-second retention; memory purged on tab close

Compliance StandardGDPR Article 25 (Data Protection by Design), HIPAA, and CCPA aligned

Frequently asked questions

How much smaller will my PDF get?: It depends on how much of the file is images. Scans and photo-heavy documents often shrink a lot, while a text-only PDF may barely change. After compressing, the tool shows the size before and after, and with Light, Balanced or Strong, if no saving was possible it returns your original file unchanged and says so.
Will the text still be selectable and searchable?: Yes, with Light, Balanced or Strong. Those levels only touch the images, so text, links and form fields stay exactly as they were. Flatten to images is the exception: it renders every page to a picture, so text can no longer be selected, searched or read by a screen reader.
What is the difference between the compression levels?: Each level shrinks embedded JPEG images to a maximum size and re-encodes them at a set quality: Light keeps images up to 2400 px on the longest edge at 85 percent quality, Balanced 1600 px at 68 percent, and Strong 1100 px at 50 percent. Flatten to images renders each page at 120 dpi as a JPEG at 60 percent quality and rebuilds the PDF from those pictures.
Can I compress a PDF to a specific size, such as 200 KB?: Yes. Type the size under Fit under a size. The tool tries the Light, Balanced, Strong and Very strong image settings, then, if Flatten pages to images if that is the only way to fit is ticked, renders the pages as pictures at 110 dpi down to 50 dpi, and stops at the first result under the limit. The file is saved as name-under-200KB.pdf. If the limit cannot be met, you get the smallest version it reached and a note saying so.
Is my file uploaded to a server?: No. The images are decoded, resized and re-encoded on your own device using your browser's built-in JPEG support. Nothing is sent to FreeAIPDF or anyone else.
Why did my file not shrink at all?: The standard levels only re-encode JPEG images in RGB or grayscale. Images stored in lossless formats, CMYK images, transparency masks and very small images are skipped, and a PDF that has already been optimized has little left to give. For a scanned document, Flatten to images usually gives a much larger saving.
Does it work on scanned PDFs?: Yes. If each scanned page is stored as a JPEG, Light, Balanced and Strong re-encode it and keep any existing text layer. Scans stored in other formats, such as black-and-white CCITT or JBIG2 images, are skipped by those levels. Flatten to images works on any scan because it renders the page, but it discards the text layer, so if you need the scan to stay searchable, run OCR PDF on the result afterwards.

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Compress PDF online, free – Make a PDF smaller or fit a size limit