🛡️ GuardX402

Stop Runaway Agent Spend.

Policy controls and audit logs for every x402 payment your AI agents make.

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What is GuardX402?

AI agents are spending real USDC autonomously — making x402 payments to APIs, data feeds, and compute services with no guardrails.

GuardX402 sits between your agent and every x402 payment. Before any payment executes, GuardX402 checks it against your policy. Approved or blocked in under 200ms. Everything logged. Your team sees it all in real time.

Agent → POST /api/guard/check → Policy Check → Approved → OWS Signs → x402 Payment
                                      ↓
                                  Blocked → Agent Stops

How it works

1. Register your agent at guardx402.com — set a budget, per-call limit, and alert threshold.

2. Add one line to your agent code:

const check = await fetch('https://guardx402.com/api/guard/check', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': 'ng_your_key_here'
  },
  body: JSON.stringify({
    endpoint: 'https://api.perplexity.ai/chat',
    amount: 0.002,
    chain: 'BASE'
  })
});

const { approved, reason } = await check.json();
if (!approved) throw new Error(`Blocked: ${reason}`);
// proceed with x402 payment

3. Done. GuardX402 tracks spend, enforces policy, and alerts your team.

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Test it right now — no signup needed

curl -X POST https://guardx402.com/api/guard/check \
  -H "Content-Type: application/json" \
  -H "x-api-key: ng_demo_research_key" \
  -d '{"endpoint":"https://api.perplexity.ai","amount":0.002,"chain":"BASE"}'

Expected response:

{
  "approved": true,
  "budgetRemaining": 4.998,
  "budgetLimit": 5.00,
  "auditId": "audit-xyz789"
}

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OWS Integration

GuardX402 is built on the Open Wallet Standard by MoonPay.

• OWS handles secure key storage and transaction signing — private keys never touch your agent code
• GuardX402 handles spend policy enforcement, budget tracking, and audit logging

import { createWallet, signMessage } from '@open-wallet-standard/core';

// Create encrypted agent wallet — keys stored at ~/.ows/
const wallet = createWallet('my-agent');

// GuardX402 checks policy → OWS signs if approved
const check = await fetch('https://guardx402.com/api/guard/check', {
  method: 'POST',
  headers: { 'x-api-key': 'ng_your_key_here' },
  body: JSON.stringify({ endpoint, amount, chain: 'BASE', owsSigned: true })
});

const { approved, auditId } = await check.json();
if (!approved) throw new Error('Blocked by GuardX402');

const sig = await signMessage(wallet, 'evm', canonicalMessage);

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API Reference

POST /api/guard/check

Check a payment against the agent's policy before executing.

Field	Type	Description
endpoint	string	Full URL being paid
amount	number	USDC amount from 402 response
chain	SOL | BASE	Chain for payment
owsSigned	boolean	Whether OWS will handle signing

Block reasons:

Reason	Description
budget_exceeded	Would exceed daily/weekly/monthly limit
per_call_max	Single call exceeds maximum
domain_blocked	Domain not in allowlist (Pro)
velocity_exceeded	Too many calls per hour (Pro)
agent_paused	Agent paused by team owner

POST /api/guard/confirm

Log the on-chain transaction hash after payment settles.

{
  "auditId": "audit-xyz789",
  "txHash": "0xabc123...",
  "owsSigned": true
}

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Plans

	Free	Premium	Pro
Price	$0/mo	$15/mo	$35/mo
Agents	1	5	Unlimited
Checks/mo	500	10,000	50,000
Audit history	7 days	30 days	90 days
Webhooks	❌	✅	✅
CSV export	❌	✅	✅
Velocity controls	❌	❌	✅
Domain allowlist	❌	❌	✅
Team seats	1	3	10

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Stack

Layer	Technology
Framework	Next.js 16.2.2 App Router + TypeScript
Database	Supabase (PostgreSQL) + Drizzle ORM
Cache	Upstash Redis
Auth + Billing	Crossmint (embedded wallet + NFT subscriptions)
Wallet Signing	Open Wallet Standard v1.2.4
Payment Protocol	x402
Chains	Solana + Base
Styling	Tailwind CSS

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Why GuardX402 vs enterprise solutions?

	GuardX402	Enterprise alternatives
Signup	Email, 2 minutes	Sales call required
Pricing	From $0/mo (Free plan)	Custom enterprise pricing
Setup	One line of code	Complex integration
Chains	Solana + Base	Usually EVM only
OWS support	✅ Native	❌ None
Open source	✅ MIT	❌ Closed source
Target	Solo devs to enterprise	Enterprise only

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Local Development

git clone https://github.com/luacantu/guardx402.git
cd guardx402
npm install

Copy .env.example to .env.local and fill in your keys:

cp .env.example .env.local

Required environment variables:

DATABASE_URL=
SUPABASE_URL=
SUPABASE_ANON_KEY=
UPSTASH_REDIS_REST_URL=
UPSTASH_REDIS_REST_TOKEN=
CROSSMINT_SERVER_API_KEY=
CROSSMINT_PRO_COLLECTION_ID=
NEXT_PUBLIC_CROSSMINT_PROJECT_ID=
NEXT_PUBLIC_CROSSMINT_PRO_COLLECTION_ID=
NEXT_PUBLIC_CROSSMINT_CLIENT_KEY=
NEXT_PUBLIC_CROSSMINT_ENVIRONMENT=staging

Run the development server:

npm run dev

Push the database schema:

npx drizzle-kit push

Seed demo data:

curl http://localhost:3000/api/seed

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Built for the OWS Hackathon

GuardX402 was built for the Open Wallet Standard Hackathon — three rounds of building on the OWS protocol by MoonPay.

OWS + GuardX402 = complete agent payment safety stack.

OWS gives agents wallets. GuardX402 gives those wallets spending rules.

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License

MIT © 2026 Luana Cantu

Built in Miami, FL 🌴

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guardx402.com · @luacantu · OWS Hackathon