Chrome Extension

Audit in your sidepanel.
Inspect elements live.

Check your HTML emails for CSS compatibility, spam triggers and accessibility, side by side inside your browser. Point, click, fix.

Open, point, fix

1
Open your email render

Open a local HTML file in your browser, or view templates in Mailgun, Klaviyo, HubSpot, or your own dashboard.
2
Turn on Inspect Mode

Point at any container, CTA button or text node to isolate its CSS support errors.
3
Audit in the sidepanel

Diagnostics update side by side. Expand a warning to see the code fix.

Hover over any block, table, button or image inside your email render to pinpoint exactly which styles break.

Free, and fully functional. The visual element inspector comes with the free tier.

Point at any of these

Side-by-side audits

Your email on the left, live preflight scores in the sidepanel on the right.
CSS support warnings

Flexbox, grid, gap, aspect-ratio and the styles Gmail, Outlook or Yahoo silently strip.
Accessibility diagnostics

Contrast ratios, and alt text on every image for screen readers.
Deliverability checks

Payload size, and a warning before Gmail clips the email at 102KB.
Auto-reload sync

The audit refreshes whenever you save in your local code editor.

Fifteen of them:

15 free local audits per day with no account needed. Sign up free for 30 audits per day.

Available on Chrome Web Store. Install once, audit in any browser tab.