HttpMaster - HttpMaster is a professional software tool for testing and debugging HTTP applications, primarily aimed at REST API applications and web services.
Zonka Feedback - Top feedback app designed to collect customer feedback on iPad & Android tablets, Online Surveys on Website, Mobile, Email & SMS. Track NPS & Other Metrics.
Hoppscotch - Open source API development ecosystem
FeedbackServer - asp.net survey software Web based and open source software, for purchase or hosted, written in ASP.NET for Nsurvey
Request inspector - Debug web hooks, http clients
KeySurvey - KeySurvey provides survey and questionnaire tools.