Guerrilla Mail vs mail.tm

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.

mail.tm issues disposable inboxes on shared domains and exposes a Hydra/JSON-LD REST API to create accounts, fetch a bearer token, and read incoming messages, all without any signup fee. It's the fully free, actively maintained sibling of mail.gw.