httpbin.org : A simple HTTP Request & Response Service.
MailCatcher : Catches mail and serves it through a dream.
MailCatcher runs a super simple SMTP server which catches any message sent to it to display in a web inter...
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Webhook Tester : Webhook Tester allows you to easily test webhooks and other types of HTTP requests.
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
MailHog is an email testing tool for developers:
Configure your application to use MailHog for SMTP delivery
View messages in the web UI, or retrieve them with the JSON API
Optionally release messages to real SMTP servers for delivery