Finding a truly free PDF redaction tool is harder than it should be. Most search results lead to tools that either require expensive subscriptions, add watermarks to free outputs, or — worst of all — only apply visual overlays instead of permanently removing sensitive data. When you need to redact a PDF for free, you need a tool that performs real, permanent content removal without hidden costs.
This guide compares every major option for free PDF redaction in 2025, explains what to watch out for, and walks you through the fastest free method available today.
What "Free Redaction" Should Actually Mean
Before comparing tools, let us define what a legitimate free PDF redaction tool should provide:
- True permanent redaction. The text must be removed from the PDF data structure, not just covered with a visual element.
- No mandatory signup. You should not have to create an account or provide an email address for basic redaction.
- No watermarks on output. The redacted PDF should not contain branding or watermarks from the tool.
- Secure file handling. Your document should be encrypted during upload and not stored on the service's servers.
Option 1: AI-Redact (Best Free Option)
AI-Redact is a browser-based PDF redaction tool that offers a free tier with AI-powered automatic detection of sensitive information. It is the only free tool we have found that combines all four criteria above: true permanent redaction, no signup required, no watermarks, and encrypted file handling.
The free tier supports PDFs up to 4 pages. The AI automatically detects names, email addresses, phone numbers, Social Security numbers, addresses, financial account numbers, and other personally identifiable information. You review the detections, confirm what to redact, and download the permanently redacted PDF in seconds.
For documents longer than 4 pages, the pro tier offers pay-per-page pricing starting at $0.08 per page with no monthly subscription — you only pay for what you use.
Option 2: Adobe Reader (Cannot Redact)
This is the most common misconception. Many people search for "redact PDF free" expecting Adobe Reader (the free version) to include redaction tools. It does not. Adobe Reader only supports viewing, printing, and basic annotations like highlights and comments. The redaction feature is exclusive to Adobe Acrobat Pro ($239.88/year).
Critically, using Adobe Reader's drawing or highlight tools to place black rectangles over text does not constitute redaction. The text remains in the file and can be easily extracted.
Option 3: Mac Preview (Visual Only — Not Secure)
Apple's Preview app on macOS includes markup tools that let you draw black rectangles or use the redaction-style markup. However, Preview's redaction behavior has been inconsistent across macOS versions. In some versions, the markup only adds an annotation overlay and does not remove underlying text. Even in versions where Preview claims to redact, the reliability is questionable enough that security professionals do not recommend it for sensitive documents.
Option 4: Online PDF Editors (Mostly Visual Overlays)
Tools like Smallpdf, PDFescape, and Sejda offer free PDF editing that includes drawing tools and shape tools. While you can draw black rectangles over text, these tools generally do not perform true redaction — they add visual overlays that can be removed. Some have added "redaction" features, but many still operate on the annotation layer rather than modifying the document structure.
Additionally, many free online editors have significant limitations: daily usage caps, required signups, watermarks on output, or file size restrictions. Some also store uploaded files on their servers, raising privacy concerns when handling sensitive documents.
Option 5: LibreOffice Draw (Technical, Imperfect)
LibreOffice is a free, open-source office suite that can open and edit PDFs. You can theoretically delete text elements and replace them with black shapes, but this process is manual, tedious, and unreliable. LibreOffice does not natively render PDFs perfectly — formatting, fonts, and layout often break. It is not a practical option for redaction.
How to Redact a PDF for Free with AI-Redact
Here is the complete process, which takes about 30 seconds for most documents:
- Open AI-Redact in your browser. No download or installation needed.
- Drag and drop your PDF onto the upload area, or click to select a file from your device.
- Wait a few seconds while the AI scans your document. It automatically identifies sensitive data including names, emails, phone numbers, SSNs, addresses, and account numbers.
- Review the AI's detections. Toggle items on or off, or manually select additional areas to redact.
- Click to apply the redaction and download your permanently redacted PDF.
The entire process is free for documents up to 4 pages, with no signup, no watermarks, and no limitations on redaction quality.
What to Watch Out for with Free Tools
- "Redaction" that is really just annotation. Test by trying to select or search for "redacted" text in the output.
- File storage policies. Some free tools store your uploaded documents. Read the privacy policy before uploading sensitive files.
- Watermarks or branding on the output. Some tools add visible watermarks unless you upgrade to a paid plan.
- Mandatory account creation. If a tool forces you to sign up before you can use it, consider whether you want that service to have your email address associated with your sensitive documents.