Put it into practice
- Export a sample in each relevant format.
- Inspect text and flat-color edges.
- Choose the smallest file that preserves the needed quality.
What this looks like
A UI-heavy browser image keeps cleaner fine edges as PNG.
A detail to keep clear
JPEG does not preserve a transparent background.
Using MockupX
MockupX exports PNG and JPEG, with WebP and 2× output available to Pro accounts. Export requires sign-in, and free exports carry a watermark. A transparent background remains transparent only in a format that supports it. Inspect the downloaded file, not only the editor preview.
Check the result
Keep the original screenshot, then review the exported file at the size where people will see it. Check the message, the visible interface and the final crop separately. For a handoff, record the destination and the approved file so another person can distinguish the final version from a draft.
References and further reading
Use the official references for format behavior and current destination requirements. The composition advice above is a practical design approach, not a promise of platform approval.
MDN image formats ↗