Kong - An open-source management layer for APIs and microservices.
Postman - The Collaboration Platform for API Development
Tyk - Tyk is an open-source API gateway and API management platform.
Apigee - Intelligent and complete API platform
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
KrakenD - KrakenD is a pure open source API Gateway that interacts with all your different microservices providing clients a single interface. Improves response times, saves bandwidth, delivers a better user experience and saves developers time.