How to add a timestamp to photos you have already taken

You took the photos, and now someone wants to see when. The good news is that the date is usually already hidden inside the file. The job is to make it visible without changing it.

The date is probably already there

Almost every phone camera saves the date and time inside the photo file, along with the location if location was switched on for the camera. You can see it on the phone by opening the photo and looking at its details or info panel.

The trouble is that nobody else can see it. Clients and landlords look at the picture, not the file data, and many messaging apps remove that data when they send a photo on. A visible stamp in the corner of the image travels with the picture wherever it goes.

What iPhone and Samsung can do

• iPhone: in the Photos app you can open a photo, tap the More button and choose Adjust Date & Time. Apple's guide describes this as changing the saved date. It does not print anything onto the picture.
• Samsung Galaxy: many recent models have a Watermark option in the Camera app settings with a Date and time switch. Samsung's own guide says it applies only to photos taken after you turn it on, and the menu varies by model and software version.
• Neither phone, going by its maker's support pages, has a built-in button that stamps a visible date onto photos you have already taken.
• Third-party timestamp apps can do it. Before you use one, check whether it uploads your photos and whether it adds its own watermark.

Stamp existing photos with the free tool

1. Open the timestamp tool. Go to the free timestamp tool on this site on your phone or computer. It runs in the browser, so there is nothing to install and your photos are not uploaded.
2. Choose your photos. Pick the JPEG or PNG files you want to stamp. Use the originals from your camera roll where you can, rather than copies saved from a chat.
3. Check the date and time. The tool reads the date and time saved in each photo, plus GPS coordinates if the photo has them. Compare each stamp with when you remember taking it.
4. Download the stamped copies. Save the new images and send those to your client, landlord or office.
5. Keep the originals. Leave the untouched files where they are. If anyone questions the stamp, the original file data is what backs it up.

Keep the stamp honest

A stamp added afterwards is a label. It shows what the file says, and it is only as trustworthy as the file it came from. Never change a photo's date to make it fit a story, as that undoes the point of the stamp and can be spotted.

If a photo has no date in it, for example a screenshot or an image saved from a group chat, there is nothing reliable to stamp. Say so, rather than guessing.

For work you photograph regularly, it is easier to capture the record at the time. In JobProof, photos are taken inside a job, and the app records who took each photo and who completed the job and when, so you are not stamping anything later.

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