How to validate AMP markup?

AMP validation is strict-invalid markup causes the entire AMP portion to be ignored, falling back to HTML. Use Google's official AMP Playground (amp.dev/playground) or the Gmail AMP for Email Playground (amp.gmail.dev/playground) to validate your code before sending. These tools parse your markup and report specific validation errors with line numbers and explanations.

Common validation failures include: disallowed HTML tags (script, style in body, certain form elements), invalid AMP components (incorrect syntax or missing required attributes), CSS violations (external stylesheets, @import, !important in some contexts), and invalid URLs (non-HTTPS resources, missing CORS headers on endpoints). Each error must be fixed-AMP validation is all-or-nothing.

Beyond markup validation, test end-to-end functionality: do your server endpoints respond correctly to AMP requests? Do forms submit and return appropriate responses? Does real-time content load within acceptable timeframes? Validation tools confirm your markup is syntactically correct; testing confirms your email actually works. AMP validation is the gatekeeper-invalid code means no interactive experience, just fallback HTML. Validate early, validate often.