soapUI - SoapUI Pro is one of the most prominent API testing platforms around, allowing developers to quickly prototype the functions of their apps and get them to market with little hassle.
Boomi - The #1 Integration Cloud - Build Integrations anytime, anywhere with no coding required using Dell Boomi's industry leading iPaaS platform.
Requester - HTTP client plugin for Sublime Text with an expansive feature set, modern UX, elegant syntax and...
Postman - The Collaboration Platform for API Development
API Test Base - API test automation tool that has GUI, supports HTTP stubs (mock services), data driven testing, and API types beyond HTTP, such as relational database, JMS, FTP(s), AMQP, MQTT, etc.
Zapier - Connect the apps you use everyday to automate your work and be more productive. 1000+ apps and easy integrations - get started in minutes.