httpbin.org : A simple HTTP Request & Response Service.
Hurl : Hurl is a command line tool that runs HTTP requests defined in a simple plain text format.
It can chain requests, capture values and evaluate queries ...
Webhook Tester : Webhook Tester allows you to easily test webhooks and other types of HTTP requests.
Litmus : Test and track your emails. Email previews, analytics and spam filter testing.
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...
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