devZing - Bugzilla, MantisBT and Subversion Hosting Software Development - Simplified
Request inspector - Debug web hooks, http clients
GoReplay - GoReplay is an open-source tool for capturing and replaying live HTTP traffic into a test environment.
Webhook.site - Instantly generate a free, unique URL and email address to test, inspect, and automate (with a visual workflow editor and scripts) incoming HTTP requests and emails.
Testlio - Testlio is a community of expert testers that help companies release their apps with highest confidence
MockServer - Easy mocking of any system you integrate with via HTTP or HTTPS.