Debugging
Email HTML Inspector
Checks email template HTML for missing unsubscribe links, broken links, images without alt text, merge tags and markup that inboxes block.
- Runs in your browser
- Free to run
- You enter
- Pasted HTML, or an .html or .zip file.
- You get
- A safe preview, a verdict, an issue list and tables of links, images and merge tags.
- A good result
- No errors, an unsubscribe link found, every image with alt text.
On this page
#What it is for
Use it before importing a template from an agency or another platform, or when a campaign renders badly in some inboxes.
#What you enter
- Paste HTML, or drop a file:
.htmlup to 2 MB, or a.zipup to 25 MB (at most 400 files, 60 MB unpacked) with an HTML file and its images.
#How it works
The HTML is read in your browser without running it. Images and styles from a zip are shown from the zip. It looks for:
| Finding | Level |
|---|---|
<script>, <iframe>, <object>, <embed> | Error |
No unsubscribe link, images without alt, empty or # links, <form> | Warning |
http:// links or images, no DOCTYPE, no charset | Info |
It also lists tracking pixels, merge tags ({{ }}, %% %%, *| |*, {% %}, [[ ]]), style blocks, the title and the preheader text.
#Reading the results
The verdict is a pass, "HTML works but has issues to review" (warnings) or "HTML has content that will break in email clients" (any error). Fix errors first; inboxes strip scripts and frames, so content inside them disappears.
Check the merge tag list against the syntax your sending platform uses: a tag from another platform is sent to recipients as plain text.
#Example
<a href="https://example.com/?utm_source=newsletter">Open offer</a>
<img src="https://example.com/banner.jpg" alt="Spring banner">
<a href="{{unsubscribe}}">Unsubscribe</a>#Limits and gotchas
- An unsubscribe link is recognised by words like unsubscribe or opt-out in the link or its text; a custom wording may be missed.
- The preview is a browser, not an inbox. Rendering in Outlook or Gmail can still differ.
- Links are listed, not opened. Follow important ones with the Redirect & UTM Inspector.