Postman : Save requests and organize your APIs into Collections. Create and send any HTTP request using the awesome Postman request builder. Write your own test...
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
mail-tester.com : Free online service that allows you to test your emails for Spam, Malformed Content and Mail Server Configuration problems
Postal : Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready f...
mountebank : mountebank is the first open source tool to provide cross-platform, multi-protocol test doubles over the wire. Simply point your application under tes...
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