Start with one image or two
Use one image for a fast reveal, or choose separate feed and opened images.
How it works
Three steps. Everything happens locally in your browser.
Tune the previews
Adjust crop, strength, brightness and contrast while checking light and dark backgrounds.
Download transparent PNG
Save one PNG, upload it to X, then verify the result on the devices you care about.
Why the image changes on X
A transparent pixel is blended with the background behind it. The same PNG can therefore look different against a light feed and a dark image viewer.
Alpha compositing
For every pixel, the browser combines the PNG color with the background using its alpha value. This tool solves a safe grayscale approximation for both target images.
visible = source × α + background × (1 − α)Compatibility
The effect depends on X, the app version, the device and the selected theme.
X WebUsually works; verify after upload
X on iOSCan vary by app version
X on AndroidMore likely to be re-encoded
Light modeShows the first image
Dark mode / viewerReveals the hidden image
There are no guarantees. X can re-encode PNGs or change its rendering at any time.
Troubleshooting
Both images show at once
Increase hidden strength, use a brighter first image, or choose a darker hidden image.
The images are misaligned
Use the crop controls to adjust zoom and position for each image independently.
X removed the effect
Reduce dimensions or file size, upload the PNG directly, and avoid editing it in another app.
It works on one device only
Test X Web, iOS and Android in both themes. Their rendering can differ.
Frequently asked questions
Is Tap and Hold free?
Yes. There is no sign-up, payment or usage limit.
Do you upload or store my images?
No. Image decoding, processing and PNG export happen in your browser. The files are not sent to our server.
Which files can I use?
PNG, JPEG and WebP inputs are supported. The downloaded result is a PNG with an alpha channel.
Will the effect always work on X?
No. X may re-encode images or change transparency behavior. Treat the previews as guidance and test the published post.
Can I use this for deceptive or harmful content?
No. Respect copyright, privacy and X rules. Do not use the tool for fraud, harassment, illegal, sexual or harmful content.
Guides
Learn how to create, post and troubleshoot an X hidden image before publishing.