AWSAmazon API GatewayNetworking

`aws_apigatewayv2_api` cost estimation

HTTP and WebSocket APIs. HTTP API is 70% cheaper than REST API: $1.00 per million requests vs $3.50. WebSocket connections billed separately by connection-minute and messages.

API Gateway v2 covers two API protocols: HTTP APIs and WebSocket APIs. The aws_apigatewayv2_api resource sets the protocol via the protocol_type attribute.

HTTP APIs are the modern replacement for REST APIs (aws_api_gateway_rest_api). Pricing: $1.00 per million requests for the first 300M/month, $0.90 for next 700M, $0.80 above 1B (us-east-1). Compared to REST APIs at $3.50/million, HTTP APIs are 70% cheaper.

The trade-off: HTTP APIs have fewer features. Missing from HTTP APIs vs REST: request/response transformations, AWS WAF native integration (only via CloudFront), private endpoints, X-Ray tracing fine-grained. For most workloads (auth + Lambda backend + CORS + simple routes), HTTP APIs cover the requirements.

WebSocket APIs pricing has three components: - Message count: $1.00 per million messages - Connection minutes: $0.25 per million connection-minutes - Data transfer: standard internet egress at $0.09/GB

A WebSocket app with 10,000 concurrent connections active for 8 hours = 4.8B connection-minutes = $1,200 just in connection minutes. Plus messages. WebSocket APIs are expensive at scale; consider alternatives (AppSync, Lambda@Edge) for high-volume real-time.

c3x estimates v2 API costs based on protocol_type and expected request/message volume from c3x-usage.yml.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "aws_apigatewayv2_api" "http" {
  name          = "production-api"
  protocol_type = "HTTP"

  cors_configuration {
    allow_origins = ["https://app.example.com"]
    allow_methods = ["GET", "POST"]
    allow_headers = ["content-type", "authorization"]
  }
}

resource "aws_apigatewayv2_integration" "lambda" {
  api_id                 = aws_apigatewayv2_api.http.id
  integration_type       = "AWS_PROXY"
  integration_uri        = aws_lambda_function.api.invoke_arn
  payload_format_version = "2.0"
}

resource "aws_apigatewayv2_stage" "prod" {
  api_id      = aws_apigatewayv2_api.http.id
  name        = "prod"
  auto_deploy = true
}

Pricing dimensions

What you actually pay for when you provision aws_apigatewayv2_api.

Dimension	Unit	What's being charged
HTTP API requests	per million requests	Requests billed in 512 KB increments. Tiered pricing reduces rate above 300M/month. $1.00/M up to 300M, $0.90/M next 700M, $0.80/M above 1B
WebSocket messages	per million messages	Messages sent or received over WebSocket connections. $1.00 per 1M messages
WebSocket connection minutes	per million connection-minutes	Connection time across all WebSocket connections. The bill driver for high-concurrency apps. $0.25 per 1M connection-minutes
Data transfer out	per GB	Internet egress from the API. Standard AWS data transfer rates. $0.09/GB tier 1

Optimization tips

Common ways to reduce aws_apigatewayv2_api cost without changing the workload.

Use HTTP API instead of REST API

70% on request fees

HTTP APIs are 70% cheaper than REST APIs ($1/M vs $3.50/M). For most workloads (Lambda backend, JWT auth, simple routing), HTTP APIs are fully sufficient. Migrate REST → HTTP for substantial savings.

Front public APIs with CloudFront

50-95% on requests

CloudFront caching reduces API Gateway requests dramatically. A 95% cache hit rate cuts API requests to 5% of original. Plus CloudFront's egress pricing is lower for many regions.

Use AppSync for high-volume WebSocket

AppSync (managed GraphQL with subscriptions) is often cheaper than raw WebSocket APIs for real-time. AppSync bills $4 per million queries + $2 per million real-time updates, but has built-in caching and connection management.

Close idle WebSocket connections

$0.25 per million idle-minutes saved

WebSocket connection minutes bill continuously. Idle connections (heartbeats only) still bill. Implement client-side connection close after N minutes idle. Saves on connection-minute fees for long-lived but unused connections.

FAQ

Why is HTTP API cheaper than REST API?

HTTP APIs are AWS's newer architecture, designed for the most common use cases (Lambda/HTTP backend, JWT auth, CORS, simple routes). They skip features that have low usage (transformations, complex auth). The simpler internal architecture lets AWS price them lower.

Can I migrate REST API to HTTP API?

Sometimes. If your REST API uses request/response transformations, AWS WAF, private endpoints, or other REST-only features, you can't migrate directly. For simple proxy-to-Lambda APIs, migration is straightforward — change protocol_type and update integration_type from AWS to AWS_PROXY.

Are WebSocket APIs ever cost-effective?

For modest-concurrency real-time apps (under a few thousand concurrent users), yes. At higher concurrency, the connection-minute fees grow linearly with users × time. Alternatives like AppSync subscriptions or self-hosted on EC2/ECS become competitive above 10K concurrent connections.

What's the AWS Free Tier for API Gateway v2?

1M HTTP API requests/month for 12 months for new accounts. WebSocket APIs have 1M messages and 750K connection-minutes/month for 12 months. After the free tier, standard rates apply.