Cost Optimization Reference

Detailed Cost Analysis

Per-service cost breakdown, before/after optimization comparison, checklist:

• cost-optimization.md
• cold-start-optimization.md — Cold start optimization with cost impact analysis (Phase 1 complete, Phase 2 in progress)

Cost Validation (Required for Infrastructure Changes)

Verify the following resources are NOT created:

Prohibited Resource	Monthly Cost	Alternative
NAT Gateway	~$33	Fargate Public IP
ALB/ELB	~$18-25	API Gateway
Interface Endpoint	~$7/each	Public IP for public endpoint access
DynamoDB Provisioned	Variable	PAY_PER_REQUEST
Lambda in VPC	Requires NAT	Deploy outside VPC

Cost Targets

Category	Target
Within Free Tier	~$0.23/month
After Free Tier	~$1.07/month
Maximum allowed	Under $10/month

Lambda Agent Cost (Phase 2)

See cost-optimization.md §9 for full Lambda cost analysis.

Resource	Cost Model	Notes
Lambda invocations	Per-request	1M requests/month free tier
Lambda duration	Per GB-second	400K GB-seconds/month free tier
Lambda container image	ECR storage	~$0.10/GB/month after 500MB free
No Fargate idle cost	—	Lambda scales to zero automatically

Key advantage: Lambda charges only for actual execution time — no idle Fargate cost when no users are active. For low-traffic usage, Lambda runtime cost approaches $0/month within free tier.