API Gateway — When to choose which?

apigw-when-to-choose.md

API Gateway: When to Choose Which

Decision Flow

Need real-time/persistent connections?
    → WebSocket API

Need transformations, API keys, usage plans?
    → REST API

Simple proxy, cost/performance optimized?
    → HTTP API

HTTP API

Best For:

• Low latency requirements
• Cost optimization (70% cheaper)
• Simple proxy to Lambda/HTTP
• JWT/OAuth2 authorization
• Modern REST APIs

Not Ideal For:

• Request/response transformation
• API keys needed
• Usage plans/throttling
• Complex request validation

Use When:

Building new APIs, microservices, serverless backends

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REST API

Best For:

• Request/response transformation
• API keys & usage plans
• Fine-grained throttling
• Mock integrations
• SDK generation
• Request validation models
• Legacy system integration

Not Ideal For:

• Cost-sensitive projects
• Ultra-low latency needs
• Simple proxy scenarios

Use When:

Complex enterprise APIs, partner integrations, detailed control needed

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WebSocket API

Best For:

• Bi-directional communication
• Real-time data streaming
• Chat applications
• Live dashboards
• Gaming backends
• IoT device communication

Not Ideal For:

• Request-response patterns
• Traditional REST operations
• Batch processing

Use When:

Real-time, persistent connections required

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Feature Comparison

Feature	HTTP API	REST API	WebSocket API
Pricing	Lowest	Moderate	Pay per message
Latency	Fastest	Good	Real-time
Authorization	JWT, OAuth2, Lambda, IAM	Lambda, Cognito, IAM, API Keys	Lambda, IAM
Transformations	Limited	Full VTL	Lambda only
Caching	No	Yes	No
Throttling	Basic	Advanced	Per route

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Quick Reference

• HTTP API: Default for new projects
• REST API: When you need control
• WebSocket: Real-time only