EXIF.
The single richest source of identifying information in an ordinary photograph, and the reason this tool exists.
EXIF (Exchangeable Image File Format) is a block of tagged fields that cameras and phones write into a JPEG alongside the picture. It carries the capture timestamp, the camera make, model and often serial number, the exposure settings, frequently the GPS coordinates, sometimes the owner's name, and usually an embedded thumbnail. In a JPEG it lives in an APP1 segment whose payload begins with the identifier Exif\0\0.
What it is
Structurally, EXIF is a TIFF file embedded inside a JPEG segment: a byte-order marker, a header, and a chain of image file directories, each a list of numbered tags with types and values. IFD0 describes the main image. A GPS pointer tag leads to a sub-directory holding latitude, longitude, altitude and a timestamp. IFD1, if present, describes a second, smaller image — the thumbnail — stored in full inside the block.
All of that survives being emailed, uploaded to most forums, and sent through most chat apps. Some social platforms strip it on upload; you cannot tell which from the outside, and you cannot undo an upload that did not.
Why it matters
GPS coordinates in a modern EXIF block are typically accurate to within a few metres — accurate enough to identify a home, a workplace, or a route walked. The capture timestamp places you there at a moment. The device serial links a set of otherwise unrelated photographs to one camera.
The embedded thumbnail is the sharpest edge. It is generated at capture time, so if you crop something sensitive out of a photo, many editors leave the original uncropped thumbnail sitting in the metadata. People have been identified by a thumbnail of a picture they thought they had cropped.
--no-keep-orientation drops it too.
Related terms
Common questions.
Does removing EXIF change the picture?
No. EXIF lives in a segment before the compressed image data, and removing a segment does not touch the data that follows it. ScrubPony copies everything from the SOS marker to end of file verbatim, so the picture is bit-identical.
Do social networks already strip EXIF?
Many do, some do not, some strip it from the displayed copy but keep the original, and none of them tell you which. Stripping it before upload is the only version of this you control.
Is EXIF the only place GPS hides?
No. XMP packets frequently carry the coordinates again, and some vendors record location in their own undocumented segments. ScrubPony drops XMP and drops unrecognised APPn segments by default for exactly this reason.
Get ScrubPony
Strips identifying metadata out of JPEGs without touching a pixel. C99, no dependencies beyond libc, macOS and Linux, MIT-licensed.