View and remove photo metadata

A photo file has two parts. One is the picture: the pixels, compressed. The other is a set of labeled blocks around it. Each block follows its own standard, which is why the names sound like a row of license plates. This is what they mean.

• EXIF is the block that the camera writes. It holds the date and the time, the make and the model of the camera or the phone, the lens, the exposure, and often serial numbers. The software field names the app or the system version that wrote the file.
• GPS is a part of EXIF. It holds the latitude, the longitude, and often the altitude. A phone fills it in when the camera may use the location. It marks the spot where you stood.
• Maker data is a part of EXIF in the camera maker's own format. Each maker uses it in its own way, and its content is not documented for the public.
• IPTC comes from news photography. It holds a caption, keywords, the name of the photographer, and place names such as the city and the country.
• XMP is a block of text that editing apps write. It can repeat the location and the date, and it can list the edits and the app that made them.
• Content credentials (C2PA) are a signed record of how a picture was made and edited. Cameras and apps that support the standard add it.
• The embedded preview is a small second copy of the picture, stored so that a file browser can show it fast.
• Comments are free text that an app or a person added.

The tool reads these and sorts what it finds into five groups: location, date, camera, software, and other data. A group with nothing in it is left out, so a short list means a file that holds little.

Remove all metadata takes out the blocks in the list above that it finds: EXIF with the GPS part and the maker data, IPTC, XMP, content credentials, comments, the embedded preview, and data that sits after the end of the picture. A second picture behind the first, such as an HDR gain map, stays, so that the photo looks the same. After the removal, the page shows a report with two lists, Removed and Kept, so you can see what happened to your file and not only what the tool does in general.

Two things stay, because the picture needs them to look the same.

Orientation

A camera sensor has one fixed shape. When you hold the phone upright, the camera stores the picture sideways and writes one number that says "turn this by 90 degrees". Without that number, your upright photo lies on its side. The tool keeps that one number.

Color profile

The color profile says what the color numbers in the file mean. Many phone cameras record a wider range of colors than the web standard. Without the profile, a screen has to guess, and reds and greens turn dull. The profile describes colors. It says nothing about where or when the photo was taken.

The picture stays byte for byte

The tool works on the file itself. It cuts the metadata blocks out and leaves the compressed picture data as it was, byte for byte. So the clean copy has the same pixels, the same sharpness, and the same size in pixels as your original. The file gets a little smaller, or keeps its size where the metadata is overwritten in place.

Special cases

• A second picture in the file. Some phones store a second picture after the first one, such as the gain map that makes an HDR photo bright on an HDR screen. The tool keeps it, so the photo looks the same, and clears the metadata around it.
• Metadata that cannot be read. A damaged or unknown block is removed whole. The tool takes it out without reading it, and the report says so.
• A file with nothing to remove comes back unchanged, and the page says that there was nothing to remove.
• A damaged file, or one that is cut short, gives a message and no download.

JPEG

The format of most cameras and of most photos on the web. Metadata sits in segments before the picture. The tool removes those segments. In a JPEG with a second picture, each metadata segment keeps its length and is filled with zeros, so that every part of the file stays where the file says it is.

HEIC

The High Efficiency format of the iPhone camera. Here the metadata is overwritten in place with zeros, so the clean file has the same size as the original and the same structure. The tool reads and cleans HEIC in every browser. The preview in the frame appears where the browser can show HEIC, as Safari does.

PNG

The format of screenshots. A PNG holds metadata in text chunks, a time chunk, and sometimes an EXIF chunk. The tool removes them and keeps the chunks that describe color.

WebP

A format that many websites use. EXIF and XMP sit in their own chunks, and the tool removes them. The color profile chunk stays.

The download keeps the format and the name of your file, with -no-metadata added to the name. IMG_1234.HEIC becomes IMG_1234-no-metadata.HEIC.

In Safari on an iPhone, Choose a photo lets you pick from the Photos library or from Files. Pick a photo, and the tool lists what is in the file that Safari hands to it. Read the list before you remove anything: it is the fastest way to see what a photo of yours would tell another person.

The iPhone has a control of its own for one part of the metadata. Apple describes it in its guide Manage location metadata in Photos: in the Photos app, select the photos, tap the Share button, tap Options, and turn off Location. That switch is about the location. The date, the camera model, and the rest of the metadata are a different matter, and this tool is for them.

Three cases where the tool is the shorter way:

• The photo is a file in Files, in Downloads, or in an email, and not in the Photos library.
• You want to take out the camera, the date, and the software too, and not only the place.
• You want to look at a file that someone sent you and see what it holds.

Safari saves the clean copy to the Downloads folder, which you find in the Files app. Share it from there. Your original in Photos stays as it is, with all its metadata, which is what you want for your own library: the date sorts it and the place puts it on your map.

The tool is a program that your browser downloads once and then runs on your own phone or computer. When you choose a photo, the browser hands the file to that program in memory. The clean copy is made in memory too, and Download saves it from the browser to your device. No part of this sends the photo anywhere.

You can verify that on a computer in two minutes:

1. Open the developer tools of the browser and select the Network panel.
2. Choose a photo and remove its metadata.
3. Read the list of requests. You see the page's own files from milkglass.app, among them the tool's program, a file that ends in .wasm. Every one of them comes down to you.
4. Look for a request that carries your photo up. A photo has several megabytes, so it would stand out. The list has none.

One more address appears in the list: ingest.postdeploy.dev. It counts page views, and it counts that the tool was used. That count names the tool and holds nothing about the file: no name, no size, no content. You can open the request and read what it sends.

The site also carries a content security policy, a rule that the browser enforces. It names milkglass.app and that one counting address, and the browser blocks a connection to every other origin. I wrote the tool this way because a tool that removes private data from a photo should do its work where the photo already is: on your device.

A clean copy is for sharing. For the photos you keep to yourself, I make Milkglass, an app that keeps them in Drawers on your iPhone. More about it is at the end of this page.

• Remove the location from a photo takes out the GPS position and the place names and keeps the date and the camera.
• Cover or pixelate part of a photo hides what the picture itself shows: a license plate, a name, an address, a face.