Features /HTML vs Text Diff

Compare the HTML and plain text parts of any email

The Diff tab in LocalMail.dev puts the HTML and plain text versions of a multipart email side by side. Check that your plain text fallback is accurate, complete, and consistent with the HTML before the email ever leaves your machine.

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Make sure your plain text fallback is correct

A well-formed transactional email should always include a plain text part. Spam filters use it to assess legitimacy, accessibility tools read it when HTML rendering fails, and some enterprise email clients strip HTML entirely. Yet the plain text part is often forgotten or auto-generated once and never reviewed again.

The Diff tab strips HTML tags from the HTML body and places it alongside the raw plain text part so you can read both versions together. Gaps in content, outdated copy, or missing CTAs in the plain text become obvious immediately.

The Diff tab only appears when the email contains both parts, keeping the toolbar clean for single-part emails.

  • Side-by-side view of HTML (stripped) and plain text
  • Appears only for multipart emails that have both versions
  • Scroll both panels independently
  • Monospace font for easy content comparison
HTML (stripped) 
Welcome to MyApp

Hi Alex,

Thanks for signing up. Click
the button below to confirm
your email address.

Confirm Email

If you did not create an
account, you can ignore
this email.
Plain Text 
Welcome to MyApp

Hi Alex,

Thanks for signing up.
Confirm your email here:
https://myapp.test/confirm
?token=abc123

If you did not create an
account, ignore this.

Frequently asked questions

What does the Diff tab show in LocalMail.dev?

The Diff tab shows the HTML body and plain text body of a multipart email side by side. The HTML column strips all tags so only the text content is visible, making it easy to compare wording, line breaks, and content coverage between the two parts.

When is the Diff tab available?

The Diff tab only appears when the captured email contains both an HTML part and a plain text part. If the email is HTML only or plain text only, the tab is hidden. This keeps the interface clean for emails that do not require a diff.

Why should I check the plain text version of my email?

Some email clients, spam filters, and accessibility tools rely on the plain text part of a multipart email. If the plain text is empty, outdated, or contains different wording than the HTML, it can affect deliverability scores and accessibility. The Diff tab makes it easy to spot these discrepancies before sending.

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