mail.gw vs MailCheck.ai

mail.gw is a temporary/disposable email API that issues throwaway inboxes for testing signups and email-verification flows. Its Hydra/JSON-LD REST API is rooted at api.mail.gw, exposing /domains (available disposable-email domains) and /messages collections, with no API key required for the base entrypoint.

MailCheck.ai has rebranded to UserCheck, but its original keyless lookup endpoint keeps working unchanged: pass an address and get back disposable, free-provider, MX, and domain-age signals in one JSON response, aimed at blocking throwaway signups. The rebranded product adds a free-to-start paid tier for higher-volume, authenticated use.