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UICheck vs Sizzy
Sizzy is a paid desktop browser for developers: it shows your site on many devices side by side, keeps scrolling and clicks in sync, and adds tools for building responsive layouts. UICheck runs in the cloud and does the looking for you: it tests every screen size, finds the bugs and writes them up.
Side by side
UICheckSizzy
SizzyWhat it isUICheck: Automatic responsive and layout QA for any URLSizzy: Desktop browser for developing responsive sites
How you testUICheck: Paste a URL; findings are listed for youSizzy: Browse many synced devices and inspect them
InstallUICheck: Nothing, runs in the cloudSizzy: Desktop app
Automatic bug reportUICheck: Yes, every screen size, with screenshotsSizzy: No, you spot problems while browsing
Safari and Firefox enginesUICheck: Yes (Lens and Prism)Sizzy: Chromium-based previews
Report for clientsUICheck: Plain-language fixes, share link without login, PDF and ExcelSizzy: Screenshots you take yourself
Based on public information, checked October 2026. Something changed? Tell us and we’ll update it.
Choose Sizzy if
- You are a front-end developer who wants many synced devices open while coding
Choose UICheck if
- You want bugs found and listed, including ones that are easy to miss
- Non-developers run checks or read the results
- You check whole sites before launch
Or use both
Build in Sizzy, then run UICheck on staging as a final check across sizes and browsers.
Also compare
Try UICheck next to Sizzy
Free account, 5 checks a day, no card. Paste a URL and see what it finds in about a minute.