API Gateway: Exploring 10 Use Cases From Authentication to Rate Limiting

Today, AI APIs are fast becoming the glue that holds modern applications together. As the number of services grows, especially in microservices architectures and serverless environments, an API gateway becomes essential. It serves as the “front door” for all external and internal requests, handling everything from traffic routing to advanced security policies.

For the uninitiated, learn what is an API gateway here. 

Who Uses an API Gateway?

Developers and architects of microservices-based systems rely on API gateways to simplify service discovery and routing. Instead of coding authentication, rate limiting, or protocol translation into every service, they delegate those responsibilities to a central gateway.

Along with them, DevOps and platform teams often use API gateways to standardize the deployment process, monitor traffic, and implement operational safeguards (like circuit breakers). This centralized approach offers better control and visibility over the entire service ecosystem.

Product managers, too, leverage API gateways to quickly roll out and test new features, ensuring consistent user experiences across multiple platforms. 

Exploring 10 API Gateway Use Cases

1. Authentication

An API gateway ensures that only authorized users or services can access your APIs. The gateway acts as the first line of defense, verifying credentials before requests reach backend services.

Common Methods

1. OAuth2/OpenID Connect for secure token-based authentication
2. JWT (JSON Web Tokens) to embed user information, enabling stateless authentication
3. API Keys for straightforward, though more limited, security in certain use cases

Centralizing authentication at the gateway level offloads logic from individual microservices, reducing duplication and potential security gaps.

2. Rate Limiting

Rate limiting ensures fair resource usage and protects backend services from overwhelming traffic or denial-of-service (DoS) attacks. It also helps manage cost and capacity planning by preventing excessive calls.

Types of Limits

1. User-Level Limits: Each user or API key is allotted a specific number of requests within a time window.
2. Global Limits: Restrict total inbound requests regardless of the user or client.

API gateways often implement token bucket or leaky bucket algorithms, which are configurable via simple rules or code-based plugins.

3. Use an API Gateway to Create HTTP APIs

Many services communicate over HTTP. An API gateway can expose internal microservices using HTTP endpoints efficiently, acting as a unified interface for various internal components or third-party integrations.

Scenarios

1. Simple Webhooks: Handling inbound requests from payment gateways, messaging services, etc.
2. Internal Microservices: Providing a stable route for inter-service communication while keeping internal topologies private.

By consolidating all HTTP endpoints under a single domain or subdomain, developers gain consistency and can more easily apply monitoring, security, and documentation practices.

4. Use an API Gateway to Create REST APIs

REST is a widely adopted architectural style for web services. Using an API gateway, you can expose resources as REST endpoints without requiring every microservice to manage RESTful routes individually.

Features

1. Path/Verb Routing: Handle GET, POST, PUT, and DELETE with standardized endpoints.
2. Query Parameters & Versioning: Keep track of evolving service interfaces without disrupting consumers.

Thanks to familiar endpoints and consistent documentation, this ensures easier onboarding for external developers and internal teams.

5. Caching

API caching improves performance and reduces latency for end users by storing responses for common or repeated requests.

Typical Configuration

1. In-memory Caching within the gateway for ultra-fast responses.
2. CDN Edge Caching if your gateway is integrated with or sits behind a content delivery network.

Use proper cache headers (Cache-Control, ETag, etc.) to balance performance gains with the need for fresh data.

6. Data Transformation & Orchestration

An API gateway can convert XML to JSON or vice versa, ensuring compatibility between clients and services that may speak different “languages.”

Two areas where it helps: 

1. Payload Modification: Gateways can sanitize or enrich requests and responses—redacting personal data, adding headers, or normalizing request fields.
2. Orchestration: Instead of having the client call multiple services in sequence, the gateway can aggregate calls and provide a single endpoint. This reduces round trips and simplifies client-side logic.

7. Load Balancing & Traffic Shaping

1. Load Balancing: Distributing traffic across multiple instances or containers helps ensure high availability and optimal resource utilization.‍
2. Traffic Shaping: Roll out new features to a subset of users via blue-green deployments or canary releases. You can also direct traffic by geography, user role, or other attributes.

8. Monitoring & Logging

Gateways act as a single entry point for all requests, making them a natural location to collect logs, metrics, and traces.

1. Real-Time Analytics: Tools like Prometheus, Grafana, or commercial monitoring solutions can track response times, error rates, and throughput in real time.
2. Benefits: Pinpoint performance bottlenecks and fix errors quickly, improving overall system reliability and user satisfaction.

9. Security Enforcement (WAF, Threat Detection)

As the frontline of your API ecosystem, gateways are an ideal place to implement security checks and Web Application Firewall (WAF) rules.

1. Intrusion Detection: Gateways can filter out common attacks like SQL injection, cross-site scripting (XSS), and malicious payloads through predefined rulesets or machine learning-based threat detection.
2. Configuration: Integration with external security services or enabling advanced plugins offers flexible threat mitigation strategies.

10. Canary Release & A/B Testing

Rolling out new features gradually minimizes risk, allowing you to gather feedback without impacting all users.

1. Implementation: Route a small percentage of traffic to a new service version. If all goes well, gradually increase that percentage.
2. Benefit: Faster experimentation with less risk of downtime or negative user impact.

Key Considerations Before Exploring Use Cases

Before exploring all the potential use cases on an API gateway, the following things should be considered: 

• Scalability & Performance: Ensure your chosen API gateway can handle expected (and unexpected) traffic. Look for high throughput and low latency.
• Security & Compliance: Implement SSL/TLS termination, secure token handling, and any mandatory compliance (GDPR, PCI DSS, etc.).
• Maintainability: Each feature—authentication, rate limiting, caching—adds complexity. Make sure your team has the resources to manage these features effectively.
• Cost & Tooling: Compare managed solutions (e.g., AWS API Gateway, Azure API Management) versus self-hosted options (Kong, NGINX, Istio) for cost, community support, and integration ease.

Conclusion

API gateways serve as the backbone of modern application ecosystems, offering a single point of control for authentication, rate limiting, caching, load balancing, and more. By implementing these use cases wisely, you can build a robust, scalable, and secure environment that delights both developers and end users.

Arya.ai’s API Gateway Nexus allows you to implement the use cases to build a robust, scalable, and secure environment that delights both developers and end users.