# Cost optimization
<a name="cost-optimization"></a>

 For serverless API cost optimization, [Serverless Application Lens](https://docs.aws.amazon.com/wellarchitected/latest/serverless-applications-lens/welcome.html) covers cost optimization best practices such as cost-effective resources, matching supply and demand, expenditure awareness, and optimizing over time in [Cost Optimization Pillar](https://docs.aws.amazon.com/wellarchitected/latest/serverless-applications-lens/cost-optimization-pillar.html) section. 

 For REST and HTTP API pricing, see [Amazon API Gateway pricing](https://aws.amazon.com/api-gateway/pricing/). You might incur additional charges if you use API Gateway in conjunction with other AWS services, or transfer data out of AWS. 

* Table 4 – REST and HTTP API pricing *


|  Endpoint type  |  Pricing  | 
| --- | --- | 
|  REST  |  Free tier: one million API calls per month for up to 12 months. <br /> API calls: 1.   First 333 million requests (per month): $3.50 (per million)  <br />2.   Next 667 million requests (per month): $2.80 (per million)  <br />3.   Next 19 billion requests (per month): $2.38 (per million)  <br />4.   Over 20 billion requests (per month): $1.51 (per million)  <br /> Caching: Billed per hour based on the cache memory size (not eligible for free tier)  | 
|  HTTP  |  Free tier: one million API calls per month for up to 12 months. <br /> API calls (us-east-1); 1.   First 300 million requests (per month): $1.00 (per million)  <br />2.   300\+ million requests (per month): $0.90 (per million)  <br /> HTTP APIs are metered in 512 KB increments.  | 

 For private integration with REST APIs, the original approach required a Network Load Balancer (VPC link V1). With VPC links V2, you can now use either an ALB or an NLB. The NLB cost is billed per hour, so while a VPC link remains active, you pay for the NLB. The ALB cost is billed per ALB running per hour and per Load Balancer Capacity Units (LCU) used per hour. For a use case where requests to a REST API are made infrequently, such as five requests per day, a VPC-enabled Lambda function can be a more cost-effective option. VPC-enabled Lambda functions can access VPC resources. Because Lambda bills per request and code execution duration, using a VPC-enabled Lambda function can cost less. See [Elastic Load Balancing pricing](https://aws.amazon.com/elasticloadbalancing/pricing/) and [AWS Lambda Pricing](https://aws.amazon.com/lambda/pricing/). 

 *Table 5 – Private integration vs. Lambda pricing *


|  Integration/Lambda  |  Cost  |  Use cases  | 
| --- | --- | --- | 
|  Private integration (NLB)  |  Billed per NLB running per hour and Network Load Balancer Capacity Units (NLCU) used per hour.  |  If there is a backend service hosted in ECS or other target such as EC2 instances that can be directly integrated with NLB, using an NLB to route traffic simplifies the architecture.  | 
|  Private integration (ALB)  |  Billed per ALB running per hour and Load Balancer Capacity Units (LCU) used per hour.  |  If there is a backend service hosted in ECS or other target such as EC2 instances that can be directly integrated with ALB according to the architecture patterns.  | 
|  VPC-enabled Lambda  |  Lambda pricing is billed on-demand, so if a Lambda function is not used, there is no charge.  |  If there is any private resource like RDS which cannot be directly accessed by NLB, using a VPC-enabled Lambda function is a good alternative.  |