Litmus : Test and track your emails. Email previews, analytics and spam filter testing.
Frisby.js : Frisby is a REST API testing framework built on node.js and Jasmine that makes
testing API endpoints easy, fast, and fun. Read below for a quick overv...
Webhook Tester : Webhook Tester allows you to easily test webhooks and other types of HTTP requests.
httpbin.org : A simple HTTP Request & Response Service.
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...
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