Free browser-local utility
See the post before you publish it.
Preview timeline and expanded states, inspect PNG transparency, and catch practical file risks without uploading your image.
What this checks
A visual preview and a file-level sanity check.
The timeline simulation shows how much detail remains when an image is constrained inside a social post. The expanded simulation uses the available stage to show the complete file without turning the page into a generic image viewer.
The browser also reads the image dimensions, format, file size, and a scaled sample of its Alpha channel. These checks help identify common problems before an image is sent through another compression step.
What this cannot promise
X controls the final rendering behavior.
Social platforms can change cropping, compression, transparency handling, and client-specific display rules. This tool is a preparation aid, not an official emulator or a guarantee of third-party behavior.
For an important campaign, publish a private or low-risk test from the same device flow you plan to use. Upload the original exported PNG directly instead of forwarding it through a messaging app.
Transparency checklist
Protect the Alpha channel all the way to upload.
- 01Export the final reveal as PNG, not JPEG.
- 02Avoid apps that flatten or recompress the image.
- 03Inspect both a light and dark preview background.
- 04Test the real publishing flow before a major post.
Questions before posting
X image preview FAQ
Does the preview checker upload my image?
No. Image loading, pixel sampling, and preview rendering happen inside your browser. The source file is not required to leave your device.
Can the checker guarantee how X will display my image?
No preview can guarantee a third-party platform's current rendering behavior. The checker provides a practical feed and expanded-view simulation plus file-level risk checks.
Why does PNG transparency matter for reveal images?
Reveal-style images can depend on Alpha information. Converting the output to JPEG or flattening it in another app removes transparent pixels and can break the intended effect.
What image formats can I inspect?
The checker accepts JPG, PNG, and WebP files up to 10 MB. PNG is the safest final format when the image needs transparency.
Why is my image marked as fully opaque?
The sampled pixels contain no Alpha values below the detection threshold. The file may have been flattened, converted, or exported against a solid background.