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APIs are a pivotal aspect of software development. They are what enable applications to communicate with each other and access data. However, in a distributed microservices architecture, one request for data will involve calls to numerous independent services and applications, creating a proliferation of messages that can be extremely difficult to track, secure and appropriately manage.
To make sure that these calls are properly routed in a timely manner, enterprises can implement an innovative messaging mechanism: the API gateway. In essence, the API gateway provides a single point of entry into a distributed architecture, managing all requests and responses as API calls that the gateway routes appropriately. The API gateway offerings available today also include numerous tooling options that will support authentication, analytics, load balancing, cache management, dependency resolution and more.
Many development tool providers -- both proprietary and open source -- have jumped at the chance to provide API gateway tools, and there are plenty of options choose from. Choosing the right one will depend on both your development shop's specific needs and the development platforms your teams depend on.
Here's a list of the most popular API gateway tools from both proprietary and open source providers.
Large cloud proprietary options
Amazon API Gateway. Part of AWS's suite of cloud platform tools, API Gateway is a fully managed service that is used to create, deploy, manage, monitor and secure APIs, including those based in REST, HTTP and WebSocket protocols. It also focuses on features geared toward resiliency and lifecycle management. API Gateway, of course, integrates easily with other AWS services and tools, such as CloudTrail for logging, Identity and Access Management (IAM) for authentication and CloudFormation for API creation. Users can access the Amazon API Gateway through a number of AWS access points, such as a management console, CLI or SDK.
Azure API Gateway. Microsoft's Azure API Management service features an API gateway as one of its three major components, alongside Azure portal (the administrative interface) and Developer portal (the developer interface). Azure's gateway accepts and routes HTTP calls, enforces usage and rate limits, caches back-end responses, logs calls and handles verification. Azure offers different features for a range of defined pricing tiers, which range from a consumer-level option that provides a pay-per-use API gateway to a premium tier designed for enterprise-level production that provides Active Directory integration, Virtual Network support and a self-hosted gateway. The gateway tool also integrates with Azure services like Monitor for diagnostics and Logic Apps for workflow and orchestration.
Oracle API Gateway. As part of the Oracle Cloud Infrastructure services, Oracle's fully managed API gateway provides RESTful APIs to back-end services that support cloud-native apps. Developers can publish APIs with private end points and access them through their own network, as well as expose them to public IP addresses for internet traffic. It includes key features such as policy enforcement, metrics and logging. Paired with Oracle Functions, developers can create serverless RESTful APIs. Also, for security, the gateway is integrated with Oracle Cloud Infrastructure IAM.
Third-party open source options
Kong Gateway. Kong Gateway is a highly scalable, open source API gateway optimized for microservices and distributed architectures. Kong built the gateway on top of top of the NGINX web server, and governs it using the Apache 2.0 license. Kong provides API gateway tools through an open source library of plugin components that add traffic control mechanisms, analytics support, authentication methods and serverless functions that help software teams create custom domains. The gateway also allows developers to configure requests and responses on the fly.
Tyk API Gateway. Tyk is another open source gateway option made up of three distinct components: the Dashboard that provides an interface for metrics and API organization; the Pump, which provides data persistence and database connections; and the Gateway, which is the proxy that handles all traffic. The Tyk API Gateway only requires a Redis database to run, and it offers similar features to Kong, including traffic proxying methods, access controls and logging capabilities.
Express Gateway. Express Gateway is an open source option built on Express.js. It is made up of four core components: a centralized declarative config that stores API use case configurations as a single YAML or JSON file; a consumer and credentials management module for API access; a distributed persistent data store that allows global data access and scalability across multiple instances; and a plugin system that allows developers to extend policies, pipelines, conditions and actions. Some plugin features also include additional authentication, API customization, rate limiters and serverless capabilities.