What are some alternatives?
When comparing Amazon API Gateway and Postman Collections, you can also consider the following products
Apigee - Intelligent and complete API platform
DreamFactory - DreamFactory is an open source REST API backend for mobile, web, and IoT applications.
Paw.cloud - Paw is a REST client for Mac.
AWS CloudTrail - AWS CloudTrail is a web service that records AWS API calls for your account and delivers log files to you.
Gravitee.io - Gravitee.io is a flexible, lightweight and an open source API management solution.
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.