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AWS API Gateway pricing calculator
A REST API costs $3.50 per million requests and an HTTP API costs $1.00, so the same traffic is 3.5 times dearer on REST before anything else is added. This prices both for your numbers, with the REST cache and the data going out, so you can see what the REST features actually cost you each month.
REST API
HTTP API
REST API a month
$0
HTTP API a month
$0
Prices for US East (N. Virginia) from aws.amazon.com/api-gateway/pricing and the AWS Price List (published 2026-10-13), checked 2026-11-06. REST: $3.50 per million for the first 333 million requests a month, $2.80 for the next 667 million, $2.38 for the next 19 billion, $1.51 above that. HTTP: $1.00 per million for the first 300 million, $0.90 above, each request metered per 512 KB. WebSocket: $1.00 per million messages for the first billion, $0.80 above, metered per 32 KB, and $0.25 per million connection minutes. Cache: billed per hour for each stage it is on, 730 hours. Data out to the internet at $0.09 a GB, the first-10-TB EC2 rate; the 100 GB a month AWS gives free across the whole account is left out, as in AWS's own examples. Not included: the Lambda or container behind the API, CloudWatch logs, WAF, private APIs (PrivateLink is billed instead of data out) and new-account Free Tier credits.
Why the bill grows
Mostly it's the API type nobody chose. The Serverless Framework's http event, a lot of older tutorials and plenty of copied CloudFormation create REST APIs, and REST is $3.50 per million requests where HTTP is $1.00. If the API uses none of the things only REST has (API keys and usage plans, AWS WAF, request validation, the cache, private endpoints, X-Ray), the extra $2.50 per million buys nothing.
The cache is the second line. It's billed every hour it exists, per stage, whether it serves a single hit or not. A 1.6 GB cache is $27.74 a month; someone turns it on in staging to test, and that's two. Check the hit rate in the CacheHitCount and CacheMissCount metrics before you keep paying for one.
Data out is the same on both types, because it's the EC2 transfer rate. It only moves with response size, so gzip and leaner JSON cut it on either one.
The worked example, $530.14 a month on REST and $202.40 on HTTP, is in AWS API Gateway pricing: REST costs 3.5x what HTTP does. If the API is one line on a bigger AWS bill, our free cloud cost audit reads the whole bill, and we cut startup AWS bills for $0 up front, paid from half the verified saving for 6 months. The function behind the API is priced in the AWS Lambda pricing calculator.