What metadata is — and why it matters

In photographs taken with a smartphone or camera, metadata typically includes the date and time the photo was taken, the device model, and often GPS coordinates.

This means that a photo of your home, shared online or sent to a stranger, may include the precise location where it was taken; even if the image itself gives nothing away. The same applies to a photo of an item for sale, a document photographed on a desk, or a picture sent to someone you have only met online.

Camera metadata may also include the serial number of the device, which links otherwise unrelated photos to the same camera, and editing history indicating which software touched the file.

Office documents (Word files, PDFs, spreadsheets) can carry metadata such as the author's name, the organisation the software is registered to, revision history, comments, and the dates the file was created and last edited. This information may be visible to anyone who receives the file.

A common and avoidable case: a document prepared for one recipient by editing a document prepared for another. The visible content is updated; the metadata may still name the original, along with the author and the organisation.

PDFs additionally carry producer and creator fields naming the software that generated them, and often retain the title field from the source document, which may not be the title you intended to send.

Metadata removal tools strip out the most commonly recorded fields. FormatOS includes metadata removal for images, EXIF and IPTC data, and for PDFs.

These tools reduce the most obvious identifiers. But metadata is complex, and it is worth being precise about the limits:

• Some formats store information in multiple locations, and a tool that clears one block may not clear another.
• Some applications re-add metadata when a file is saved. Stripping a file and then opening and re-saving it in an editor can reintroduce author and timestamp fields.
• Removal does not touch content-level identifiers. A visible signature, a letterhead, a watermark, a name inside the text, or a recognisable background in a photograph are all part of the content, not the metadata.
• Removal does not defeat forensic analysis. Sensor noise patterns, compression fingerprints and similar traces persist regardless of metadata.

For most everyday file sharing, built-in metadata removal is sufficient. If you are handling genuinely sensitive files: legal documents, photos with location data, or materials where identifying details could cause harm: verify the output carefully and consider using a specialist tool in addition to a general-purpose converter.

Converting a file often changes its metadata but does not reliably clear it. Some fields carry across the conversion, some are replaced by the converting software's own details, and some survive in unexpected places.

If the goal is to remove metadata, use a tool built for that and check the result. Do not assume a format change did the job.

Both the image and PDF metadata tools show you what is present before you remove anything. That inspection step is worth running on its own: not to remove anything, but to see what your device has been recording. Most people are surprised by at least one field.

For archives, inspecting a ZIP lists what is inside, including files that are easy to forget: exports, hidden system files, and earlier drafts bundled with the intended contents.

Decide first whether metadata matters for this particular file and recipient. For a holiday photo sent to family, it does not. For a document going to a counterparty, a photo posted publicly, or anything involving an address, it might.

Then remove, then verify. The verification step is the one that gets skipped, and it is the only one that tells you whether the removal worked.