Guerrilla Mail vs Kickbox

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.

Kickbox's free, keyless Open API endpoint answers a single question — whether an email domain is disposable — a common building block for lightweight signup-form validation. It's a separate, fully free offering from Kickbox's metered full verification product, which is where catch-all (accept-all) detection lives; a live probe found no catch-all surface on the open endpoint at all.