Security / Images
Steganography: Hide Text in an Image
Hide a secret message inside an ordinary-looking picture, optionally locked with a password, and read hidden messages back; the image is processed in your browser and saved as PNG.
Steganography: Hide Text in an Image: Each pixel's red, green, and blue values give up their lowest bit to carry the message, a change of at most 1 in 255 that cannot be seen. A short header marks the image and gives the message length. With a password the message is first encrypted with AES-256-GCM, so even someone who finds it cannot read it. Runs 100% locally in your browser with zero server file uploads.
- Category
- Developer tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Nothing is uploaded
The message goes into the lowest bit of each pixel's red, green, and blue values, a change no one can see, and the image is saved as PNG. Send it as a file: resizing, JPEG, or a chat app's compression wipes the message out. Without a password anyone with this kind of tool can read it; with one, it is encrypted first. Transparent areas become opaque.
How much an image can carry
Every pixel carries three bits, one in each of red, green, and blue, so an image holds three eighths of a byte per pixel, less 8 bytes for the header. A 1920 × 1080 photo has room for about 777,000 bytes, far more than any message.
A locked message takes more room, because the encrypted text is about a third longer than the original plus around 80 characters.
What it protects against
Hiding stops a casual viewer from noticing that there is a message at all. It does not stop someone who suspects one: statistical tests can detect changes to the lowest bits. For secrecy, use a password; for a whole file, use encrypt a file.
Before sharing any photo, the image metadata remover strips the location and camera details it may carry.
How to use it
- Choose Hide a message, pick an image, and type the message.
- Optionally lock it with a password, then download the PNG.
- To read it, choose Read a message, pick the PNG, and enter the password if there is one.
Privacy & limitations
Images and messages stay in your browser; nothing is uploaded.
Related tools
Frequently asked questions
Why did my message disappear?
The hidden bits do not survive lossy compression: sending the image as a photo in a chat app, resizing it, or saving it as JPEG wipes them out. Send the PNG as a file.
How long a message can I hide?
Three bits per pixel: a 1000 × 1000 image holds about 375,000 bytes. The tool shows the room in the image you choose.
Is hiding the same as encrypting?
No: tools that look for hidden data can find and read an unlocked message. Add a password to encrypt it as well.
Free tool · runs in your browser · no account required