How to Redact a PDF: A Complete Guide
Covering something sensitive in a PDF with a black rectangle is not redaction — the underlying content can often still be copied or revealed. True redaction permanently removes the content from the file. Here's how to do it correctly.
PDF redaction is a common requirement for legal documents, freedom of information responses, court filings, medical records, and any document that needs to be shared with certain information removed. It's also frequently done wrong.
The classic mistake: placing a black-filled rectangle over sensitive text in a PDF editor and calling it redacted. This doesn't remove anything — the text beneath the box is still present in the PDF's content stream. Anyone who selects all and copies, or opens the file in a text extractor, will see the 'redacted' content in full.
The Difference Between Covering and Redacting
A cover (a black annotation box placed over content) and a true redaction look identical on screen. The difference is in what's stored in the file:
- Cover/overlay: adds a black shape on top of the page content, but the underlying text, images, and vector data remain in the PDF content stream — copyable, searchable, and extractable
- True redaction: removes the underlying content from the file entirely and replaces the area with a flat black region — nothing to extract, copy, or reveal
Real-World Failure
In 2021, a US federal court filing contained 'redacted' names that were covered with black boxes but not truly redacted. Journalists selected the text and read the names. This type of accidental disclosure is common and has appeared in government filings, corporate documents, and legal proceedings.
How True Redaction Works
Proper redaction is a two-step process:
- Mark: draw redaction areas over the content you want to remove. At this stage, nothing is deleted — you're just marking regions.
- Apply: the redaction engine processes the marked areas, removes the underlying content from the PDF's content streams, and replaces each area with a solid black rectangle (or transparent region, depending on settings).
After applying redactions, the removed content cannot be recovered from the exported file — it no longer exists in the document. The file size typically decreases slightly because content has been removed rather than covered.
How to Redact a PDF in DraftPDF
- Open your PDF in DraftPDF.
- Select the Redaction tool from the toolbar (looks like a black rectangle with an X).
- Click and drag to draw a redaction mark over the content you want to remove. The area is highlighted in red to show it's marked but not yet applied.
- Repeat for each area you want to redact — you can mark multiple regions before applying.
- When all marks are placed, use Apply in the Annotations panel to commit the pending redactions.
- DraftPDF processes the document and removes the marked content permanently.
- Save or export the redacted PDF.
Tip
Review the marks carefully before applying — redaction is permanent and cannot be undone after the file is saved. Use the undo function (Ctrl+Z) to remove a redaction mark before applying if you've made an error.
What Gets Removed
The redaction tool works on any content type in the marked area:
- Text: removed from the content stream — cannot be selected, copied, or found by search
- Images: the portion of the image within the redaction area is removed
- Vector graphics: vector elements within the redaction boundary are clipped and removed
- Annotations: existing annotations (comments, highlights) that fall within the redaction area are also removed
Common Redaction Use Cases
Legal Documents and Court Filings
Many jurisdictions require personal identifying information (PII) to be redacted from publicly filed court documents — social security numbers, dates of birth, minors' names, financial account numbers. Applying true redaction rather than covers ensures compliance with court rules and avoids the embarrassing failures described above.
Freedom of Information Responses
When organisations respond to FOI or public records requests, they often need to redact exempt information — commercially sensitive material, personal data, advice to ministers — before release. True redaction is legally required in many jurisdictions; covering is not compliant.
Medical Records
Sharing patient records for research, litigation support, or multi-provider care often requires redacting patient identifiers. HIPAA in the US and similar regulations elsewhere require that this be done properly — covered text that can be extracted does not constitute de-identification.
HR and Employment Documents
Sharing employment contracts or performance reviews for reference checks, dispute resolution, or training may require redacting salary details, third-party names, or other employee-specific information not relevant to the sharing purpose.
Checking Your Redactions Are Complete
After saving a redacted PDF, verify it before sharing:
- Open the saved PDF in a different viewer (Chrome, Adobe Reader) to confirm the redacted areas appear as flat black regions.
- Try to select text in and around the redacted areas — if redaction was applied correctly, no text should be selectable from those regions.
- Use Ctrl+F (Find) to search for a word you know was in a redacted section — it should not be found.
- Optionally, open the file in a text extractor tool to confirm the content is absent from the file's text layer.
Metadata and Hidden Content
Redacting visible content is necessary but sometimes not sufficient. PDFs can contain metadata (author, creation tool, revision history), attached files, embedded comments, and other data not visible on the page. For sensitive documents, consider also:
- Removing document properties (author name, organisation, creation tool) via Document Properties before sharing
- Checking for and removing attached files embedded in the PDF
- Removing comments and annotations not intended for the recipient
- For the highest-sensitivity documents: print to PDF after redaction to produce a clean, flat file with no metadata inheritance
Privacy Note
DraftPDF performs all redaction processing locally in your browser. Documents containing sensitive PII, legal privilege, or regulated health data should not be uploaded to cloud services for redaction — the upload itself represents a disclosure. Local processing eliminates this risk.
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