Blacking out text in a PDF — also called redaction — permanently covers sensitive information so it cannot be read. Here's how to do it correctly in your browser without Adobe Acrobat.
Go to pdfeditor.onl/pdf-studio and upload your PDF.
Select the Annotation / Pen tool. Choose black color at 100% opacity and a thick stroke width. Draw over each piece of text you want to black out. The black fill covers the text completely.
Tip: For precise coverage of a specific line of text, draw a solid horizontal rectangle at maximum thickness. Make sure the black extends slightly beyond both ends of the text to avoid partial character exposure.
Zoom in to 200% and review every redacted area. Ensure no characters are visible through or around the black coverage.
Click Download PDF. The black overlay is permanently embedded. The covered text cannot be seen in the output file.
Visually yes — both produce a black rectangle covering the text. True cryptographic redaction also removes the underlying text data from the PDF stream. For highly sensitive legal or government documents, a specialist redaction tool that also removes underlying data is recommended.
With the annotation method, the black is embedded as page content. For documents requiring absolute security, use the Eraser tool which paints white over content first, then apply the black annotation on top.
Yes — all PDF Studio tools including the annotation tool are completely free.