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A practical guide to file privacy

A file can tell two stories: the content you meant to share, and the hidden information stored alongside it. These guides explain what to check and what rmmetadata can remove.

Exactly what the cleaner targets

FormatRemovedRetained / limits
JPG / JPEGApplication metadata segments and comments, including EXIF, XMP and IPTC blocks.JPEG image data, JFIF, ICC profiles and Adobe rendering information. Minimal EXIF orientation retained where needed.
PNGNonessential ancillary chunks, including tEXt, zTXt, iTXt, eXIf and dates.Image data, transparency, color and animation chunks. EXIF-rotated PNG files rejected rather than rotated incorrectly.
WebPEXIF and XMP chunks.Encoded image, ICC, transparency and animation. EXIF-rotated WebP files rejected.
PDFDocument Info dictionary, XMP metadata streams and trailer ID.Pages, annotations, attachments, forms and embedded images. Signed or encrypted PDFs rejected.
MP4 / MOVudta, meta and UUID blocks in parsed containers; creation and modification timestamps in mvhd, tkhd and mdhd headers.Media data and sample offsets remain unchanged. Codec-level tags, timed metadata tracks and proprietary fields outside parsed containers can remain. Only self-contained files with supported ftyp brands are accepted.

Metadata removal and AI detection

An image generator may write prompts or software names into PNG text chunks or XMP. rmmetadata removes those supported blocks. This does not change the image’s pixels or guarantee that another system cannot identify its origin. Visible watermarks, embedded signal patterns and content-based analysis are separate from the fields this cleaner targets.

Some metadata is necessary to display content correctly. A color profile, an image rotation value or a video timebase is retained when supported. “No supported metadata found” means the cleaner did not find its target blocks; it is not a certificate that all identifying information is absent.

Before sharing anything sensitive

  1. Keep an original and clean a copy.
  2. Review the cleaning report for the supported fields removed.
  3. Open the cleaned file and check its appearance, pages or playback.
  4. Review visible content, attachments, annotations and filenames independently.
  5. Use an independent metadata inspector if you need assurance beyond this tool’s scope.

Format references

Our implementation follows the W3C PNG specification, Google WebP container specification, Apple QuickTime format documentation and pdf-lib documentation.