MAT is a toolbox composed of a GUI application, a CLI application and a library, to anonymize/remove metadata.

Current status

The MAT maintenance and development is currently on hold, mostly for health reasons. I might go back to it at some point in the future.

The current version might have bugs, and doesn't work on Python3: Please avoid using it.

You should give a try to MAT2 instead.


What is metadata?

Metadata consists of information that characterizes data (e.g. Word documents, pictures, music files, etc). In essence, metadata answers who, what, when, where, why, and how about every facet of the data that is being characterized.

Why metadata can be a risk for your privacy?

Metadata within a file can tell a lot about you. Cameras record data about when and where a picture was taken and what camera was used. Office documents like pdf or Office automatically add author and company information to documents and spreadsheets. Maybe you don't want to disclose this information on the web.

Why MAT is not the ultimate solution?

Mat only removes metadata from your files, it does not anonymise their content, nor handle watermarking, steganography, or any overly customized metadata field/system. Also please not that MAT does its best to scrub as much metadata as possible, it's not really efficient at scrubbing embedded media inside complex formats. For examples, images embedded inside PDF may not be cleaned!

If you really want to be anonymous, use formats that do not contain any metadata, or better: use plain-text. And most important, be careful: every format can be watermarked, even plain text! (e.g. the SNOW project) You can also print out a copy of the documents, re-scan them, and pass it to the MAT; but be careful to securely shred your printout and not leave traces in your printer’s/scanner’s memory.

How does MAT work?

Proudly powered by Python, MAT was originally written during the GSoC 2011, under the umbrella of the Tor project.

Currently supported formats:

For now, MAT fully supports the following formats:

  • Portable Network Graphics (.png)
  • JPEG (.jpg, .jpeg, …)
  • TIFF (.tif, tiff, …)
  • Open Documents (.odt, .odx, .ods, …)
  • Office OpenXml (.docx, .pptx, .xlsx, …)
  • Portable Document Fileformat (.pdf)
  • Tape ARchives (.tar, .tar.bz2, …)
  • MPEG AUdio (.mp3, .mp2, .mp1, …)
  • Ogg Vorbis (.ogg, …)
  • Free Lossless Audio Codec (.flac)
  • Torrent (.torrent)

Where does MAT live?

What does it look like?

Check the screenshots page.

Who talks about MAT?

What's new?

Check the changelog.

What's next/What does(n't) work

Check the bugtracker.

What if I don't want to use the GUI?

There is a handy CLI (Command Line Interface), that can be invoked with the command mat (instead of mat-gui for the GUI). You should type mat -h to get help about it.


Since MAT is not a silver bullet, you may want to take a look at:

  • Exiftool, a Perl application for editing metadata in a wide variety of files.
  • exiv2, a C++ application to manage image metadata
  • jhead, a jpeg header manipulation tool
  • pdfparanoia, a tool to remove watermark from academic papers



If you have questions, patches, bug reports or simply want to talk about this project, please use the mailing list. You can also contact jvoisin on or drop an email to julien.voisin @, with the GPG key 0x04D041E8171901CC.