Does FixTools check email client compatibility?

FixTools validates HTML specification compliance. For email client compatibility testing (Outlook rendering, Gmail CSS support), use a dedicated email testing tool like Litmus or Email on Acid in addition to validation.

Why is validating HTML email templates especially important?

Email clients use stripped-down HTML rendering engines that do not support modern CSS or HTML5 features. Invalid HTML that browsers forgive may break completely in Gmail, Outlook, or Apple Mail. Validate before sending to catch issues early.

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HTML Validator for Email Templates

Email HTML has unique rules — table-based layouts, inline styles, limited CSS support, and strict rendering across dozens of email clients. FixTools validates your email HTML markup to catch structural errors before your campaign goes out.

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Cost: Free forever
Sign-up: Not required
Processing: In your browser
Privacy: Files stay local

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Validates email HTML structure

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Catches table layout errors

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Identifies missing attributes in email context

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HTML Validator

All processing happens in your browser — your files are never uploaded to any server.

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How to use this tool

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Paste your email HTML and validate. Structural errors that could break rendering across email clients are clearly identified.

How It Works

Step-by-step guide to html validator for email templates:

1
Paste email template HTML
Copy your complete email HTML and paste it into the validator.
2
Validate
Click Validate to check for structural errors.
3
Fix errors
Fix any structural, attribute, or nesting errors identified.
4
Test in email clients
After fixing HTML errors, test rendering in major email clients (Gmail, Outlook, Apple Mail) using an email testing service.

Real-world examples

Common situations where this approach makes a real difference:

Pre-send email template quality check

Before sending an email campaign to subscribers, validate the HTML to catch structural errors that could cause broken layouts in popular email clients.

Auditing an email template from a drag-and-drop builder

Email builders produce valid but often verbose and occasionally error-prone HTML. Validate before using a builder-created template in a production campaign.

When to use this guide

Use this before sending an email campaign to validate the HTML structure and catch markup errors that could break rendering in Outlook, Gmail, or Apple Mail.

Pro tips

Get better results with these expert suggestions:

Email HTML uses table-based layouts

Unlike web HTML, email HTML still relies on nested tables for layout. Ensure all table elements are correctly structured with proper row and cell counts.

All styles must be inline

Most email clients strip <style> blocks. All CSS must be applied as inline style attributes. Validate your HTML to confirm style attribute syntax is correct.

Always include width attributes on table cells

Email clients require explicit width attributes on table cells for consistent column sizing. Missing width attributes cause unpredictable rendering in Outlook.