HTML Email Compatibility Checker

Flag email-unfriendly HTML before you send.

Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.

HTML Email Compatibility Checker

How to use this tool

  1. Paste your email HTML and press Generate.
  2. Read the flagged patterns. Each flag explains why the pattern is risky in email clients.
  3. Use Load sample for HTML containing a script tag, which is flagged and lowers the score.

Worked example

For HTML containing a script tag, the tool flags the script, deducts 30 points and gives a compatibility score of 70 out of 100, because scripts are blocked by email clients.

What this tool does not do / Limits

This tool checks patterns in the pasted code only; it does not render the email in real clients, and a clean result does not guarantee identical rendering everywhere.

Frequently asked questions

Why are scripts flagged?

Email clients block scripts for security, so script-based behaviour will not run and the code may be stripped.

Does a score of 100 mean the email looks the same everywhere?

No. Email clients still render tables, images and styles differently; the score only means no flagged risky patterns were found.

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