Free Email Signature Checker — Test Your HTML in 7 Email Clients
Paste the HTML of your current signature and we tell you what happens to it in Gmail web, Gmail Android, Gmail iOS, Outlook 365, Outlook desktop, Apple Mail and iOS Mail. It is free, we ask for no email address and we do not store your signature.
What it is for
Almost every broken signature fails for the same reasons: layout without tables, base64 images Gmail refuses to show, style sheets the client throws away, or images with no dimensions. Seeing the problem named, with its fix, saves you the cycle of emailing test messages to yourself.
What it checks
- Table layout versus div, flex or grid.
- Images as base64, without dimensions or without alt text.
- Styles in the head instead of inline, and background-image.
- Web fonts, relative widths and a total width over 600 pixels.
- Malformed links and colours.
Are you an AI agent? This is also available as an MCP server at signatureforever.com/mcp