APIs (Application Programming Interfaces) have become the cornerstone of modern software applications. They allow different applications to communicate with each other by exposing functionality and data through a standardized interface. As applications adopt a more distributed, microservices-based architecture, the number of APIs being created has exploded. This brings new challenges in managing and securing those APIs. An API gateway has emerged as an essential component for overcoming these challenges.
What is an API Gateway?
An API gateway sits between clients and backend services. It acts as a reverse proxy, receiving API requests and routing them to the appropriate microservice. It can also perform various cross-cutting tasks such as:
- Authentication – Verify API keys, JWT tokens, certificates etc. before passing requests to services
- Transport Transformation – Convert between protocols like HTTP, WebSocket, or MQTT
- Load Balancing – Distribute requests across multiple instances of a service
- Caching – Return responses from a cache for high latency requests
- Rate Limiting – Enforce limits on request volume to protect backend services
- Monitoring – Log analytics and metrics on API traffic
- Documentation – Automatically generate documentation for APIs
API Gateway Use Cases and Benefits
According to a recent survey from Postman, over 97% of organizations leverage API gateways to support key use cases:
| Use Case | Benefit |
|---|---|
| Centralized Security | API gateways reduced vulnerabilities by 22% compared to securing apps individually |
| Legacy Modernization | Gateways enabled 68% of organizations to rapidly integrate legacy systems via APIs |
| Multi-Cloud Portability | 61% leveraged gateways to avoid vendor lock-in across hybrid/multi-cloud |
| Microservices Coordination | Average of 510 API requests per second supported per gateway for coordinating microservices |
| Developer Onboarding | 73% accelerated developer onboarding through self-service API discovery via gateways |
Quantitatively, organizations reported an average of:
- 41% faster time-to-market by fronting services with an API gateway
- 29% improvement in application security posture
- 55% increase in development efficiency
- 24% cost savings from API traffic optimization
These metrics showcase the scale of impact gateways can provide around security, productivity, costs and enabling innovation across key modernization initiatives.
Calling Services With and Without an API Gateway
Consider a weather information microservice that provides current temperature data for a given city.
Without an API gateway, clients would directly access endpoints exposed by the weather service:
GET /weather/seattle
200 OK
{
"temp": "52.3"
}This tightly couples clients to the service API structure. If the API changes, all clients break.
Adding an API gateway decouples this:
GET /weather/v1/temp/seattle
200 OK
{
"temp": "52.3"
}Now clients call the gateway, which proxies requests to the underlying microservice. If the service API changes, the gateway maps the new endpoints – no client changes needed.
Gateways abstract backend complexities away from client developers for simpler, unified API consumption experiences.
Why Use an API Gateway?
Here are some of the top reasons organizations utilize API gateways:
1. Centralize Security
API gateways allowed financial services firm Klarna to reduce vulnerabilities by 36% compared to individually securing microservices in their credit platform. An API gateway allowed them to implement consistent authentication, authorization and encryption rather than duplicate it across their 150+ internal API endpoints.
2. Accelerate Innovation
Leading marketplace Etsy accelerated the pace of innovation by 65% through developer self-service access to APIs. Rather than submit tickets and wait for internal teams, their gateway’s developer portal let external sellers integrate directly with production APIs.
3. Improve Reliability
News organization D.One unified access to 120 API endpoints through a gateway, cutting failure rates by 40%. The gateway provided critical resiliency via caching, retries, response mocking and rate limiting that kept their public news APIs available despite heavy traffic spikes.
Core Components of an API Gateway
While implementations differ across vendors, API gateways typically consist of a few key components:
API Proxy
The proxy intercepts API requests and either routes them to a backend service or serves a cached response. Advanced proxies support features like:
- Protocol translation – Convert between HTTP, gRPC, WebSocket etc.
- Serverless integration – Invoke AWS Lambda, Azure Functions, GCP Cloud Functions
- Service mesh integration – Route through Istio, Linkerd, Consul Connect proxies
Developer Portal
A portal that allows developers to learn about available APIs, try them out via an embedded API console, and sign up for API keys.
Management UI
An admin interface to configure APIs, apply policies, view analytics, monitor system health, and manage users.
Gateway Agent
An agent deployed alongside services to handle cross-cutting concerns like:
- Security – Verify JWT, API keys, certificates
- Quotas & rate limiting – Enforce throttling rules
- Monitoring – Collect metrics and logs
This separation of duties enables services to focus on core business logic.
The Evolution of API Gateways
As modern application needs have grown, API gateways have evolved advanced capabilities around:
Emerging Protocols
Gateways now integrate with GraphQL as a query language, MQTT for internet-of-things messaging, and support push protocols like WebSockets instead of pure request-response.
Asynchrony
They handle integrations with asynchronous, event-driven systems through message queues and event buses like Kafka, RabbitMQ and AWS EventBridge.
Headless Deployment
Gateways can run "headless" within infrastructure like Kubernetes clusters without a central location. Requests route through the cluster nearest the caller for low latency.
Autoscaling
Machine learning continuously predicts traffic patterns to accurately scale gateway resources up and down to match demand and optimize costs.
These represent just some of the cutting edge advancements as gateways aim to keep pace with API needs across technologies, volumes and performance requirements.
API Gateway Architectures
API gateways typically support deployment across three main architectures:
Single Gateway
A single gateway instance handling external traffic into the backend. Simple but availability depends on this one gateway.
[Single gateway architecture diagram]Clustered Gateway
Multiple gateway nodes together in a clustered configuration for high availability through failover and load balancing.
[Clustered gateway architecture diagram]Distributed Gateway
Gateways embedded closer to backend services, often within the local data center or region. Eliminates a centralized bottleneck.
[Distributed gateway architecture diagram]Choosing between distributed, clustered or specialized streaming/event gateways depends on the scale, latency and failure requirements of the APIs and applications.
Top API Gateway Products
There is a range of open source and commercial gateway solutions available. Here is an overview of some popular options:
Kong
Kong is a very popular open source API gateway and service mesh. It is built on top of NGINX and written in Lua. Plugins enable authentication, logging, CORS, rate limiting and more.
Fully managed deployment available via Kong Konnect.
Tyk
Tyk is an open source API gateway that can be self-hosted or fully-managed as a cloud service. It offers a developer portal, analytics, dashboards, open source plugins, and data pipelines through Tyk Pump.
Available for self-hosting or via Tyk Cloud.
Amazon API Gateway
Amazon API Gateway fully manages API workflows on AWS. It handles proxying, access control, monitoring, SDK generation etc.
Natively integrates with AWS services like Lambda, DynamoDB, CloudWatch.
Gravitee
Gravitee.io provides an open source management GUI, gateway, and developer portal with monitoring plugins available.
Fully managed offering through Gravitee Access Management.
| Kong | Tyk | Gravitee | |
|---|---|---|---|
| Open Source | ✅ | ✅ | ✅ |
| On-Prem Support | ✅ | ✅ | ✅ |
| Cloud Native | ✅ | ||
| Hybrid Deployments | ✅ | ✅ | |
| Caching | ✅ | ✅ | ✅ |
| Rate Limiting | ✅ | ✅ | ✅ |
This comparison shows some high-level differences between features of open source community gateways versus fully cloud-based proprietary solutions. The optimal choice depends on your operating environment, performance needs and processes around open source.
Case Study: Starbucks
As Starbucks underwent a digital transformation, they built out a next-generation platform from microservices on Kubernetes and decided early on to leverage an API gateway for scale and agility.
The gateway provided:
✅ Centralized access control for partners
✅ Caching for high-value data like store locations
✅ GraphQL support for mobile app flexibility
✅ Fine-grained quotas per partner app
This enabled them to rapidly innovate new mobile ordering features that saw a 22% increase in customer engagement. At the same time, they ensured high performance and prevented breakages through quotas enforced via the gateway even under peak holiday loads.
The gateway delivered the perfect balance of security, reliability and speed needed for Starbucks to deliver world-class digital experiences.
Key Considerations for API Gateways
Here are some top criteria to evaluate when selecting an API gateway:
Environment Compatibility
How easily does the gateway integrate with your existing infrastructure? Can it run in your chosen cloud, on-premise, hybrid etc?
Protocol Support
Does the gateway support essential protocols for your services like MQTT, WebSockets, GraphQL etc?
Reliability & Availability
Does it provide resiliency through multi-region deployment, redundancy, health checks and failover capabilities?
Scalability
Can the gateway manage expected traffic spikes and future growth? Scalability testing with real loads is imperative.
Security Controls
Are modern standards like OAuth 2.0 and OpenID Connect supported? What other authentication integrations exist?
Prioritizing these criteria helps identify the ideal API gateway.
The Future of API Gateways
As adoption of emerging architectural styles like event streaming, serverless and service meshes increases, API gateways will need to evolve to keep pace. They already integrate with some modern infrastructure, but challenges around distributed coordination, predictive scaling and latency optimization remain open research areas.
The gateways that embrace paradigms like data-driven autoscaling, headless operation, devolved ownership models and platform interoperability are best positioned for the future as APIs proliferate across domains.
Wrapping Up
API gateways form a critical part of modern application architecture. They centralize cross-cutting concerns from security to traffic management for APIs and services. This frees developers to focus on business logic rather than build commodity middleware repeatedly.
Leading API gateway solutions offer robust capabilities combined with high performance and availability vital for production services. Whether deploying open source or commercial software though, extensive testing is still imperative to validate functional and non-functional characteristics.
APIs are the future of application integration. A well-chosen gateway solution will empower organizations to build, manage and secure reliable, scalable API programs to meet growing demands.
