Disify vs Guerrilla Mail

A free, keyless REST API that checks an email's syntax, DNS/MX records, whether its domain is disposable or on an allow-list, and whether its mailbox is a role address, returning a single JSON verdict. No signup is required for the core lookup, with paid business accounts available for higher volume.

Guerrilla Mail issues disposable, auto-expiring inboxes and lets a client poll or fetch their incoming messages through a simple JSON-over-AJAX endpoint, no signup or key required. It's a fully free anti-spam utility with no paid tier.