What is Email on Acid?

You've built a beautiful email. It renders perfectly in your browser. Then it arrives in your subscriber's Outlook looking like it went through a blender. That's the problem Email on Acid was built to solve.

Email on Acid is an email testing tool that shows you how your email looks across dozens of email clients and devices before you hit send. You upload your HTML, and it generates screenshots from real rendering environments: Gmail, Outlook, Apple Mail, mobile clients, the works. What you see is what your subscribers actually get.

Beyond rendering previews, it covers a few other pre-send checks worth knowing about. Its Campaign Precheck feature runs rendering, accessibility, and spam filter tests together in one report so you don't have to run each test separately. That's genuinely useful when you're on a deadline and need everything in one place.

Here's what Email on Acid checks for you:

• Rendering previews across 90+ email clients and devices
• Accessibility checks like missing alt text, low color contrast, and font size issues
• Spam filter testing to flag content that might trigger filters before your campaign goes out
• Image blocking previews so you can see how your email looks when images don't load
• Link validation to catch broken URLs before they reach anyone's inbox

Email on Acid is often compared to Litmus, which covers similar ground. The two tools are genuinely similar, so the choice often comes down to pricing structure and which email clients you care about most. Email on Acid tends to price per user rather than per email preview, which can work out better for teams sending high volumes of test renders each month.

If you're not sure whether you need a dedicated testing tool at all, our free Accessibility Checker is a good starting point for catching the most common issues before you invest in a paid platform.