Steganography
Hide a secret text message inside an ordinary PNG image - the picture looks identical to the eye but carries your hidden note in its pixels. Switch to reveal mode later, upload that PNG, and the concealed text comes back out.
It works because the note lives in the least-significant bit of each pixel, so the download has to stay a PNG - re-saving as JPG would erase it. An optional password locks the message before it is hidden, so only someone who has that password can read it back.
Key features
- Two modes, one switch. A single control flips the tool between hiding a message and pulling one back out, so encode and decode live on the same page.
- Capacity shown up front. The moment you choose a cover image it reports the longest message that image can hold, so nothing is silently cut off.
- Optional password. Leave it blank for a plain hide, or set one and the same password is then required to reveal.
- Nothing leaves your device. The picture and the text are processed in your browser and are never sent to a server.
Message capacity and the PNG-only rule
The picture you pick decides how much you can hide and whether the hidden note survives. Three choices matter:
| Choice | What it controls | Keep in mind |
|---|---|---|
| Cover size | Roughly three hidden bits per pixel | A larger image holds a longer message; the on-screen capacity is the hard limit |
| Output format | The saved file is always a PNG | Re-saving as JPG or any lossy format wipes the hidden data |
| Password | Encryption applied before hiding | Skip it for a quick hide; set one and the reader needs the same password |
Keeping the hidden message intact
The secret lives in the pixel bits, so anything that re-compresses the picture can strip it: posting to social media, sending through a chat app, or running it through an image compressor all re-encode the file. Share the PNG as a plain file download to be safe. New to this? Read How to hide a message in an image for a step-by-step walkthrough.
Frequently Asked Questions
What does Steganography do?
Hide a secret text message inside an ordinary PNG image - the picture looks identical to the eye but carries your hidden note in its pixels.
When should I reach for steganography?
Lock the hidden message with a password, so only someone who knows it can read it back.
Is my image or message uploaded to a server?
Everything runs in your browser on your own device - the image and the message are never uploaded to a server.