WSO2 API Manager - WSO2 API Manager is a 100% open source enterprise-class solution that supports API publishing, lifecycle management, application development, access control, rate limiting and analytics in one cleanly integrated system.
Postman - The Collaboration Platform for API Development
apiman - Open source API management
DreamFactory - DreamFactory is an API management platform used to generate, secure, document, and extend APIs.
Fusio - Open source API management platform
AWS CloudTrail - AWS CloudTrail is a web service that records AWS API calls for your account and delivers log files to you.