Paste your HTML.
Drop in your full email HTML or a fragment — or load one of the built-in samples. Nothing is uploaded; it all parses in your browser.
Free tool · runs in your browser
Free HTML Email Tester — catch what breaks before you send
Paste your email’s HTML and get a 0–100 production-readiness score in seconds — the same checks a studio runs before a template ships.
Runs in your browser · nothing uploaded · no signupThis is a static analyzer, not a rendering farm. It catches the common bugs before you send — it does not render pixel-for-pixel like Outlook or Gmail (that’s what Litmus and Email on Acid do). Use it to catch what breaks; reach for a paid rendering service when you need exact screenshots.
The check battery
What the HTML Email Tester checks
Around twenty checks across four categories, each one a real, documented email-rendering or deliverability failure — the same rules the EmailTemple studio enforces on every generation.
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Deliverability
Gmail 102 KB clipping
Flags emails near or over Gmail’s ~102 KB clip point, where everything below the cut — including your unsubscribe link — is hidden.
Base64 images
Catches images embedded as base64, which bloat the file, hurt deliverability and break ESP image pickers.
Image-to-text balance
Warns when an email is mostly images and little live text — a spam signal that shows blank with images off.
Placeholder and dead links
Finds empty hrefs, # links and placeholder domains left in before you send.
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Rendering
Viewport meta
Confirms the viewport meta that lets the email scale on mobile.
Charset declared first
Checks the charset is the first tag in the head, where Outlook expects it.
Fixed-width overflow
Flags containers wider than 600px that overflow Outlook and narrow screens.
Inline CSS for core styles
Warns when color, font or background styles live only in a <style> block Gmail strips.
Image widths
Checks every image has an explicit width so Outlook sizes it correctly.
Forbidden elements
Detects scripts, forms, iframes and media elements that clients strip.
External stylesheets
Flags linked stylesheets that never load in the inbox.
Doctype
Looks for the doctype that keeps rendering predictable.
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Compliance
Visible unsubscribe link
Requires a visible unsubscribe link — hidden ones fail CAN-SPAM and GDPR.
Physical mailing address
Looks for the postal address CAN-SPAM requires in the footer.
Preheader (preview text)
Checks for preview text of a useful length, not filler like “view in browser”.
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Accessibility
Alt text on images
Flags images missing alt text that screen readers and images-off views need.
Presentational tables
Checks layout tables carry role="presentation" so assistive tech skips them.
Body text size
Warns on body copy under 14px that is hard to read on mobile.
Language set
Looks for the html lang attribute that helps screen readers.
How it works
Paste, read, fix before you send.
Read the report.
Get a 0–100 score and a pass, warn or fail for every check, grouped into deliverability, rendering, compliance and accessibility.
Fix and re-check.
Each finding comes with why it matters and how to fix it. Edit, paste again, and watch the score climb before you send.
Questions
The HTML Email Tester, in plain language.
Is my HTML uploaded anywhere?
No. The HTML Email Tester parses your email entirely in your browser with the built-in DOMParser. Nothing is uploaded, logged or stored — you can disconnect from the network after the page loads and it still works.
Does this guarantee my email renders perfectly in Outlook?
No. This is a static analyzer, not a rendering farm. It catches the common bugs that break emails before you send — it does not produce pixel-accurate Outlook or Gmail screenshots. For exact client renders, pair it with a paid rendering service.
What is the Gmail clipping limit?
Gmail clips messages larger than about 102 KB. Everything below the cut is hidden behind a “view entire message” link — including your unsubscribe link, which is a compliance problem. Aim to keep the HTML under ~80 KB.
Why does my email need inline CSS?
Gmail’s webmail strips <style> blocks, so any color, font or background defined only there disappears. Inline the load-bearing styles on the elements themselves and keep <style> for media queries and progressive enhancement.
Do I need an unsubscribe link by law?
Yes. CAN-SPAM and GDPR both require a working, visible unsubscribe mechanism in commercial email. The tester fails your email if it can’t find a visible unsubscribe link.
Can EmailTemple just build a template that passes all of this?
Yes. Every check here is a rule the EmailTemple studio already enforces on each generation. Describe what you want to send and it produces a template with inline CSS, a compliant footer, alt text and dark-mode-safe markup from the start.
Skip the checklist
Or generate email that already passes.
EmailTemple generates templates that pass every one of these checks — inline CSS, dark-mode safe, Outlook-ready, compliant footer — from a single sentence.