01What EXIF is, and why it is worth reading
Every time a camera writes a file it embeds a block of metadata describing how the photograph was made: the body, the lens if it can talk to the body, shutter speed, aperture, ISO, focal length, metering mode, white balance, the exact second, and on many cameras and every phone, GPS coordinates. It travels inside the file, so it survives copying, emailing and most editing.
The most useful thing you can do with it is study your own archive. Open the frames you actually like and look for the pattern: most photographers discover they have one focal length they genuinely see in and two that they own out of habit. It also settles arguments with yourself about whether a frame was soft because of focus or because you were at 1/30s on a 200mm lens, which is a question the numbers answer instantly and memory never does.
02The privacy part, which matters more than people think
If a file has GPS coordinates in it, they are precise to a few metres. A photograph taken in your living room carries your home address. A photograph of a child in a garden carries the location of that garden.
The large social platforms strip EXIF on upload, so posting to Instagram or Facebook is generally safe on this specific point. What is not safe is everything else: files sent as email attachments, messaging apps set to send original quality, shared cloud folders, and images uploaded to your own website or portfolio, all of which routinely keep the full block intact. If you publish your own images anywhere you control, check one of them here first. It takes ten seconds and the failure mode is publishing your address.
Turning off location tagging in the camera or phone settings is the reliable fix. Exporting through software that strips metadata works too, though it also removes your copyright and contact fields, which you may well want to keep.
03Why some files come back nearly empty
A few reasons, all normal. Screenshots and heavily processed exports often have nothing, because the software that wrote them had nothing to record or deliberately stripped it. Manual and adapted lenses have no electronic contacts, so the camera cannot know what is on the front and records no lens or aperture. Some manufacturers put a great deal of the interesting data, including lens identity and focus point, into a proprietary MakerNote block that only their own software fully decodes. And some RAW formats, notably Canon CR3, Fujifilm RAF and Panasonic RW2, use container structures this reader does not parse.
04Frequently asked questions
No. It is read by JavaScript in your own browser and never leaves your device. No upload, no account, nothing stored. Open your network tab while you use it, or disconnect from the internet after the page loads: it still works.
JPEG and TIFF-based RAW: DNG, Canon CR2, Nikon NEF, Sony ARW, Pentax PEF. Canon CR3, Fujifilm RAF, Olympus ORF, Panasonic RW2 and HEIC use container layouts this reader does not decode.
They can, to within a few metres. Social platforms usually strip it, but email attachments, messaging apps in original-quality mode, cloud links and your own website often do not. Check before you publish.
Manual and adapted lenses have no electronic contacts, so nothing is recorded. Some manufacturers also keep lens data in a proprietary MakerNote block only their own software reads.