The Problem
You built an MCP server. People use it. Claude Code calls it. Cursor calls it. LangChain agents call it.
Every call costs you money — proxies, LLM tokens, compute, third-party API fees. AI agents consume your resources for free.
You've considered charging. Here's why the obvious options fail for micropayments:
| Solution | Fee on a $0.02 call | The problem |
|---|---|---|
| Stripe | $0.31 (2.9% + $0.30) | 1,500% fee — they earn more than you |
| PayPal | $0.31 (2.9% + $0.30) | Same math, same problem |
| API keys | $0 fees | Agents can't self-register; you manage keys |
| ag402 (Solana USDC) | $0.00025 | 1.25% fee — agents auto-pay, no signup |
The core issue: AI agents can't sign up for accounts. They can't fill checkout forms or manage API keys across dozens of services. Payment needs to be programmatic and invisible.
Three Commands
pip install ag402-core
ag402 init # Creates Solana wallet + test USDC
ag402 serve \
--target http://localhost:3000 \
--price 0.02 \
--address <YourSolanaAddress>
Your MCP server now charges $0.02 USDC per request. Your code? Untouched.
┌─────────────────────────────┐
Agent request ──→ │ ag402 reverse proxy (:4020) │
│ ┌─────────────────────┐ │
│ │ 1. Check payment │ │
│ │ 2. If none → 402 │ │
│ │ 3. Agent auto-pays │ │
│ │ 4. Verify on Solana │ │
│ │ 5. Forward request │ │
│ └─────────────────────┘ │
└──────────┬──────────────────┘
│
┌──────────▼──────────┐
│ Your MCP Server │
│ (unchanged code) │
└─────────────────────┘
ag402 is a reverse proxy. It sits in front of your server and handles everything. (Step-by-step tutorial)
Buyers Don't Notice
On the agent side:
import ag402_core; ag402_core.enable()
Or zero code changes:
ag402 run -- python my_agent.py
Every 402 is intercepted → paid → retried. Works with LangChain, AutoGen, CrewAI, Semantic Kernel — anything on httpx or requests.
Speed
- Standard: ~0.5s per payment (on-chain Solana USDC)
- Prepaid mode: ~1ms — one on-chain payment buys HMAC credentials, subsequent calls verify locally with zero gas
Prepaid is indistinguishable from a free API in terms of latency. (Technical deep-dive)
Running on Mainnet
Token RugCheck audits Solana tokens for rug pull risks — live on mainnet with real USDC payments.
- $0.02/audit · RugCheck.xyz + DexScreener + GoPlus → 3-layer risk report
- Verified tx:
3QPqd3...hnVPn(verify on Solscan)
Revenue Projections
Hypothetical estimates — actual results depend on your traffic and pricing.
| Price/call | 100 calls/day | 500 calls/day | 1,000 calls/day |
|---|---|---|---|
| $0.01 | $30/mo | $150/mo | $300/mo |
| $0.02 | $60/mo | $300/mo | $600/mo |
| $0.05 | $150/mo | $750/mo | $1,500/mo |
Non-custodial — USDC goes directly to your Solana address. Only fee: ~$0.00025 network fee.
When NOT to Use This
Be honest about the tradeoffs:
- Your users don't have crypto wallets: ag402 requires buyers to hold Solana USDC. If your audience is non-crypto developers, this is a barrier. (The prepaid system reduces but doesn't eliminate this.)
- Solana network outages: Solana has had downtime events. Standard payments depend on network availability. (Prepaid mode works offline since it's HMAC-based.)
- Regulatory uncertainty: USDC is a regulated stablecoin, but crypto payment rules vary by jurisdiction.
- You need complex billing: Subscriptions, usage tiers, invoices — ag402 handles simple per-request pricing. For complex billing, you may still need Stripe alongside.
Security
Real money means real security:
- 4 security audits · 24 issues found, 24 fixed
- 588+ tests · 90%+ coverage
- 6-layer budget protection · per-tx cap ($5), rate limit, daily cap ($10), circuit breaker, auto-rollback, key redaction
- Non-custodial · private keys never leave your machine
- Zero telemetry · no tracking, no analytics
MIT licensed → audit the source
Get Started
pip install ag402-core && ag402 init && ag402 serve --target http://your-mcp:3000 --price 0.02 --address <Addr>
→ GitHub ⭐ · Live on mainnet · Colab demo · @AetherCoreDev
Open source (MIT). Built on Coinbase x402.
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