Email HTML/CSS Compatibility Checker
Paste your email's full HTML (including its styles): the tool uses static analysis to detect CSS properties and tags known to behave poorly in Outlook, Gmail, or other email clients, and lists the points to check before sending.
How it works
The tool looks in your HTML code for known patterns that cause problems in major email clients: modern CSS properties not supported by the Word rendering engine used by desktop Outlook (flexbox, grid, position fixed), interactive tags systematically blocked (<script>, <iframe>, <video>), or risky practices that vary by client (@media, CSS background images, non-inline styles). Each detection is classified as "blocking" (likely broken rendering) or "warning" (possible degradation but not systematic), with an explanation of the affected clients.
Will an email that's "clean" according to this tool display perfectly everywhere?
No absolute guarantee: this analysis is static and covers the most well-known, documented pitfalls (notably from resources like Can I Email), but it does not replace a real test on major clients (Outlook, Gmail, Apple Mail, Yahoo) via an email testing service. It's a quick first filter, not a certification of full compatibility.
Why are HTML tables still recommended for emails?
Unlike the regular web, layout with <table> remains the most reliable method in email because it has been consistently supported by all clients for a long time, including Outlook, while modern CSS techniques (flexbox, grid) remain unevenly supported.
Your email code is never sent to a server: the analysis runs entirely in your browser.