Serverless REST API with asynchronous processing

Serverless REST API with asynchronous processing Serverless REST API with asynchronous processing API Gateway → Lambda → DynamoDB, with SQS-buffered background work AWS Cloud Region Background processing HTTPS 1. Mobile / web client → Amazon API Gateway (HTTPS)1 read / write 3. AWS Lambda → Amazon DynamoDB (read / write)3 5. Amazon SQS → AWS Lambda5 6. AWS Lambda → Amazon S36 authorizer logs & metrics 2. Amazon API Gateway → AWS Lambda2 enqueue 4. AWS Lambda → Amazon SQS (enqueue)4 Mobile / web client (Mobile client) Mobile / web client Amazon Cognito (Amazon Cognito) Amazon Cognito Amazon API Gateway (Amazon API Gateway) Amazon API Gateway AWS WAF (AWS WAF) AWS WAF AWS Lambda (AWS Lambda) AWS Lambda API handler Amazon DynamoDB (Amazon DynamoDB) Amazon DynamoDB Amazon SQS (Amazon Simple Queue Service) Amazon SQS AWS Lambda (AWS Lambda) AWS Lambda worker Amazon S3 (Amazon Simple Storage Service) Amazon S3 results Amazon CloudWatch (Amazon CloudWatch) Amazon CloudWatch logs, metrics, alarms

Flow

  1. 1Mobile / web client → Amazon API Gateway (HTTPS)
  2. 2Amazon API Gateway → AWS Lambda
  3. 3AWS Lambda → Amazon DynamoDB (read / write)
  4. 4AWS Lambda → Amazon SQS (enqueue)
  5. 5Amazon SQS → AWS Lambda
  6. 6AWS Lambda → Amazon S3

Cost estimate us-east-1 · price list as of 2026-10-02 · indicative — some usage is assumed

$349per month
$4,193per year
9/10components priced
0not priced (see below)

Public on-demand AWS list prices from the AWS Price List. Excludes free tier, taxes, support plans, Savings Plans/Reserved Instances/Spot and enterprise discounts, and data transfer unless a node sets egressGbPerMonth. Monthly = 730 hours. Not a quote: confirm with the AWS Pricing Calculator.

Usage basis. Illustrative: 3M API requests/month, 20,000 monthly active users.

By category

Security and operations$323 · 92%
Integration$11.70 · 3%
Compute$10.37 · 3%
Data and storage$4.45 · 1%

By component click a row to highlight it on the diagram

ComponentServiceStatus$ / monthLine items
Amazon CognitoAmazon Cognitoestimated$300
1 line
  • Monthly active users (essentials): 20,000 CognitoUserPoolsMAU × $0.015 = $300.00

Excludes the free tier.

Amazon CloudWatchAmazon CloudWatchestimated$12.30
4 lines
  • Log ingestion (GB): 10 GB × $0.50 = $5.00
  • Log storage (GB-month): 10 GB-Mo × $0.03 = $0.30
  • Custom metrics: 20 Metrics × $0.00 = $6.00
  • Standard-resolution alarms: 10 Alarms × $0.10 = $1.00
AWS WAFAWS WAFestimated$10.60
3 lines
  • Web ACLs: 1 Month × $5.00 = $5.00
  • Rules: 5 Month × $1.00 = $5.00
  • Requests inspected: 1,000,000 Request × $0.00 = $0.60

Managed rule groups with their own fees (e.g. Bot Control) are not included.

Amazon API GatewayAmazon API Gatewayestimated$10.50
1 line
  • REST API requests: 3,000,000 Requests × $0.00 = $10.50
AWS LambdaAWS Lambdaestimated$6.77
2 lines
  • Requests (x86): 500,000 Requests × $0.00 = $0.10
  • Compute duration (GB-seconds): 400,000 Lambda-GB-Second × $0.00 = $6.6667
AWS LambdaAWS Lambdaestimated$3.60
2 lines
  • Requests (x86): 3,000,000 Requests × $0.00 = $0.60
  • Compute duration (GB-seconds): 180,000 Lambda-GB-Second × $0.00 = $3.00
Amazon S3Amazon Simple Storage Serviceestimated$3.20
3 lines
  • Storage, standard (GB-month): 100 GB-Mo × $0.00 = $2.30
  • PUT/COPY/POST/LIST requests: 100,000 Requests × $0.00 = $0.50
  • GET and other requests: 1,000,000 Requests × $0.00 = $0.40
Amazon DynamoDBAmazon DynamoDBestimated$1.25
3 lines
  • On-demand read request units: 5,000,000 ReadRequestUnits × $0.00 = $0.625
  • On-demand write request units: 1,000,000 WriteRequestUnits × $0.00 = $0.625
  • Table storage (GB-month): 10 GB-Mo × $0.00 = $0.00

On-demand capacity mode; the Price List storage tier includes its first 25 GB at no charge.

Amazon SQSAmazon Simple Queue Serviceestimated$1.20
1 line
  • Standard queue requests: 3,000,000 Requests × $0.00 = $1.20

Assumptions 20 defaulted — replace them with your own numbers in each node's usage

ComponentAssumptionValueSource
Amazon Cognitotieressentialsassumed
Amazon Cognitomau20000from spec
Amazon API Gatewaytyperestassumed
Amazon API GatewayrequestsPerMonth3000000from spec
AWS WAFwebAcls1assumed
AWS WAFrules5assumed
AWS WAFrequestsPerMonth1000000assumed
AWS LambdarequestsPerMonth3000000from spec
AWS LambdaavgDurationMs120from spec
AWS LambdamemoryMb512from spec
AWS Lambdaarchx86assumed
Amazon DynamoDBreadRequestsPerMonth5000000assumed
Amazon DynamoDBwriteRequestsPerMonth1000000assumed
Amazon DynamoDBstorageGb10assumed
Amazon SQSfifofalseassumed
Amazon SQSrequestsPerMonth3000000assumed
AWS LambdarequestsPerMonth500000from spec
AWS LambdaavgDurationMs800from spec
AWS LambdamemoryMb1024from spec
AWS Lambdaarchx86assumed
Amazon S3storageClassstandardassumed
Amazon S3storageGb100assumed
Amazon S3putRequestsPerMonth100000assumed
Amazon S3getRequestsPerMonth1000000assumed
Amazon CloudWatchlogIngestGbPerMonth10assumed
Amazon CloudWatchlogStorageGb10assumed
Amazon CloudWatchcustomMetrics20assumed
Amazon CloudWatchalarms10assumed

Sensitivity & what-if

$349at 1× traffic
$1,016at 3× traffic
$3,360at 10× traffic
  • Run AWS Lambda on arm64 (Graviton) — saves $0.60/month. Same usage re-priced with arm64 request and duration rates; assumes the code runs unchanged on arm64.
  • Run AWS Lambda on arm64 (Graviton) — saves $1.33/month. Same usage re-priced with arm64 request and duration rates; assumes the code runs unchanged on arm64.

Price list provenance

Retrieved 2026-10-01T18:40:39.861Z from the public AWS Price List bulk API. Per-service publication dates:

AmazonCognito 2026-09-25 · AmazonApiGateway 2026-09-21 · awswaf 2026-09-14 · AWSLambda 2026-09-19 · AmazonDynamoDB 2026-09-11 · AWSQueueService 2026-09-11 · AmazonS3 2026-09-28 · AmazonCloudWatch 2026-09-22

Only public on-demand rates are used. This is not a quote — confirm in the AWS Pricing Calculator.