The Problem
Every developer building AI agents faces the same issue: AI agents cannot pay for APIs. They have no credit cards, no Stripe accounts, no API keys.
The Solution: x402 Protocol
x402 uses HTTP 402 (Payment Required) to let AI agents pay for API calls automatically in USDC. No accounts, no KYC.
What I Built
XiaoKe API Gateway — 7 micro-services for AI agents:
| Service | Price |
|---|---|
POST /pdf |
$0.01 |
POST /scrape |
$0.02 |
POST /ocr |
$0.015 |
POST /review |
$0.03 |
POST /translate |
$0.01 |
POST /summarize |
$0.01 |
POST /md2html |
$0.005 |
How It Works
# First call — no payment
curl -X POST https://xiaoke-pdf-api.loca.lt/scrape \
-H "Content-Type: application/json" \
-d "{\"url\":\"https://example.com\"}"
# Response: HTTP 402 with payment details
# X-x402-Price: 0.02
# X-x402-Address: 0x039ec...
# AI agent pays 0.02 USDC on Base → retries
# Response: 200 OK with clean Markdown
Tech Stack
FastAPI + pdfplumber + BeautifulSoup4 + Apple Vision OCR + x402 protocol
Open Source
🔗 github.com/y9695430-lang/xiaoke-api-gateway
Why This Matters
Gartner predicts 75% of apps will shift to API consumption pricing by 2027. The x402 protocol has processed 119M+ transactions. AI agents are becoming the primary consumers of APIs.
Built in a day with Claude Code. AMA in the comments!