Remove hidden metadata from a PDF

Some PDFs expose an author name or the software used to create them through standard document properties. Clearing those fields can be useful before sharing a document.

A document can also disclose information in visible text, comments, file attachments, XMP and other embedded objects. Clearing basic properties does not remove all of these sources.

For sensitive documents, inspect the output with an appropriate independent tool and follow your organisation’s redaction and security procedure. Check comments, hidden layers and attachments as well as the visible pages. If a recipient requires the original signed file, do not replace it with a rewritten copy.

This tool exists for PDF documents handled in a hurry: no queue, no account, no upload, and a result you can verify on the spot. The explanation below is the same one we would give a colleague who asked how it works.

Scanned documents behave differently from every other file you have. Each page is a photograph, typically 1–3 MB at 300 dpi in colour, with no text layer unless your scanner ran OCR. That means there is no lossless cleverness available — the bytes genuinely are the picture. The cheapest wins on a scan are usually cropping the grey table edge out of every page and turning off colour where the document is black ink on white paper.

Password-protected and encrypted PDFs are not supported by these tools. If you are authorised to do so, use your PDF reader to make an unlocked copy and try that copy instead. Preserve the original, especially if it has a digital signature.

Accepted inputs are PDF files up to 50 MB. SVG, HTML and other script-bearing formats are refused outright rather than sanitised, because a file that can execute code has no business being re-encoded — and an upload field that accepts one is a security hole rather than a feature. The tool works on one file at a time, which keeps the result unambiguous.

The PDF is parsed, common Info dictionary fields are set to empty values, dates are reset to a fixed value, and the file is reserialized. XMP streams, annotations, hidden layers, attachments, scripts and identifying content may remain. This is not complete anonymisation, secure redaction or malware removal. No guarantee is made that all document features or signatures survive rewriting. The rewrite clears common title, author, subject, keywords, producer and creator fields and resets document dates. Other information, including XMP metadata, visible content, attachments or actions, can remain. It does not sanitize malware or guarantee anonymity.