Building a serverless AI agent platform on AWS for $0.01/month with Claude Code

Project Overview

Serverless OpenClaw is a full-stack serverless AI agent platform built entirely through conversational prompts to Claude Code over 29 hours across 5 weeks. The platform runs the OpenClaw AI agent on-demand on AWS with a React web chat UI and Telegram bot, deploying the entire infrastructure with a single cdk deploy command.

Technical Details

Cost Optimization: The project reduced monthly costs from a typical ~$70+ serverless setup down to $0.01/month on Lambda with zero idle costs. Specific eliminations include:

• NAT Gateway: -$32/month
• ALB (Application Load Balancer): -$18/month
• Fargate always-on: -$15/month
• Interface VPC Endpoints: -$7/month each
• Provisioned DynamoDB: Variable savings

Performance Metrics:

• Cold start: 1.35s (Lambda), 0.12s warm
• Total AWS cost during development: ~$0.25
• Monthly running cost: ~$0.01 (Lambda)

Code Quality:

• Unit tests: 233
• E2E tests: 35
• CDK stacks: 8
• TypeScript packages: 6 (monorepo)

Development Process

The entire project was built without manual coding—just prompts, reviews, and course corrections. Claude Code was used for:

• Architecture design: "Design a serverless platform that costs under $1/month" → Claude Code produced the PRD, CDK stacks, network design
• TDD workflow: Claude Code wrote tests first, then implementation (233 tests before a single deploy)
• Debugging sessions: Docker build failures, cold start optimization (68s → 1.35s), WebSocket auth issues
• Phase 2 migration: Moved from Fargate to Lambda Container Image mid-project, including S3 session persistence and smart routing

The prompts were originally in Korean, and Claude Code handled bilingual development seamlessly.

Tech Stack

TypeScript monorepo (6 packages) on AWS using: CDK for IaC, API Gateway (WebSocket + REST), Lambda + Fargate Spot for compute, DynamoDB, S3, Cognito auth, CloudFront + React SPA, Telegram Bot API. Multi-LLM support via Anthropic API and Amazon Bedrock.

Practical Patterns

API Gateway instead of ALB: Saves $18+/month. WebSocket + REST on API Gateway with Lambda handlers.

Tutorial Structure

The 7-chapter "vibe coding" tutorial documents every prompt, failure, and fix:

• Chapter 1: The $1/Month Challenge (~2h) - PRD, architecture design, cost analysis
• Chapter 2: MVP in a Weekend (~8h) - 10-step Phase 1, CDK stacks, TDD
• Chapter 3: Deployment Reality Check (~4h) - Docker, secrets, auth, first real deploy
• Chapter 4: The Cold Start Battle (~6h) - Docker optimization, CPU tuning, pre-warming
• Chapter 5: Lambda Migration (~4h) - Phase 2, embedded agent, S3 sessions
• Chapter 6: Smart Routing (~3h) - Lambda/Fargate hybrid, cold start preview
• Chapter 7: Release Automation (~2h) - Skills, parallel review, GitHub releases

Each chapter includes: the actual prompt given → what Claude Code did → what broke → how we fixed it → lessons learned → reproducible commands.