Documentation

What is Metera?

Metera is the billing infrastructure for AI agents on Solana. It implements the x402 HTTP payment protocol — the open standard backed by Google, Microsoft, Stripe, Coinbase and Cloudflare — and exposes it as a managed platform.

If you have an API, Metera lets AI agents pay you automatically in USDC, per call, with no billing setup, no credit cards, and no human approval.

If you have an AI agent, Metera gives it a Solana wallet, spending limits, and access to hundreds of paid APIs — controllable through a three-tier approval system.

How it works

Quickstart: List your first API

5 minutes from zero to a live, monetized endpoint.

Quickstart: Make your first paid API call

Read https://api.metera.xyz/skill/YOUR_AGENT_KEY and follow the instructions

Your agent can now make paid API calls automatically. It reads the skill.md, learns its wallet address, spending limits, and available APIs, then pays in USDC when it encounters an x402 endpoint.

Agent wallets

Agent wallets are managed Solana wallets created by Metera on your behalf using Privy infrastructure. Each wallet has its own address, agent key, spending limits, and tier configuration.

Create a wallet

Each agent wallet has:

Spending limits

Spending limits protect your agent from runaway costs. All limits are denominated in USDC.

All limits are optional. A null value means no limit is enforced for that window.

3-tier spending governance

Every call through the agent proxy is evaluated by the tier router before execution. The tier is determined by the call amount relative to your configured thresholds.

Deposit USDC via Pix

Metera uses 4P Finance to convert BRL to USDC on Solana via Pix. This is currently the primary deposit method.

skill.md — agent configuration

Every agent wallet exposes a public Markdown file that teaches AI agents (Claude, Cursor, GPT) how to use Metera automatically.

# Your skill URL
https://api.metera.xyz/skill/YOUR_AGENT_KEY

# In Claude Code or Cursor:
Read https://api.metera.xyz/skill/YOUR_AGENT_KEY and follow the instructions

The skill.md tells your agent:

The skill.md is public — it contains no private keys or secrets. The agentKey authenticates calls through the proxy, not access to funds.

On-chain protection — Squads v4

For paid plans (Starter, Pro, Enterprise), Metera creates a Squads Protocol v4 multisig for each agent wallet. This adds on-chain enforcement of the per-call spending limit — not just a database check.

Register your API

No code required. Go to metera.xyz/proxy, paste your upstream API URL and set a price. Metera generates a public proxy endpoint instantly.

Proxy endpoints

Each registered API becomes a proxy endpoint. Agents call the Metera URL, Metera verifies payment on-chain, then proxies the request to your upstream API with your API key injected automatically.

When you create an endpoint you can configure:

The public proxy URL is always: https://api.metera.xyz/p/{slug}

How agents pay

When an agent calls your endpoint without a payment header, Metera returns HTTP 402 with payment instructions. The agent signs a USDC transaction on Solana, includes the signature in the next request, and Metera verifies it on-chain before proxying.

Browse the marketplace

The Metera Marketplace at metera.xyz/marketplace lists all public APIs available for AI agents. Browse by category, search by keyword, or sort by popularity or recency.

Each listing shows price per call in USDC, uptime %, average latency in ms, and total calls — so agents can evaluate quality before using an API.

Supported categories include: data, ai, media, finance, and others.

# Browse all marketplace APIs
curl https://api.metera.xyz/api/marketplace

# Filter by category
curl "https://api.metera.xyz/api/marketplace?category=finance&sort=popular"

# Search by keyword
curl "https://api.metera.xyz/api/marketplace?search=weather"

# Get one API's full details
curl https://api.metera.xyz/api/marketplace/weather-api

List your API

Any endpoint registered with isPublic: true appears automatically in the marketplace. There is no manual review or approval process.

Agents across the Metera network discover and call your API autonomously — no signup flow, no API keys distributed to callers, no billing setup on either side.

The x402 protocol

x402 is an open HTTP standard for machine-to-machine micropayments. The HTTP status code 402 ("Payment Required") has existed since HTTP/1.1 but was never standardized. The x402 Foundation defines the spec.

When a server returns 402, the response body includes:

{
  "amount": 0.001,
  "token": "USDC",
  "chain": "solana",
  "recipient": "7UQctUWgfH87jjz9xjnCCKVY6Q1tMWZ8i1ZB3Whx939D"
}

The client pays on-chain and includes the transaction hash in the next request header. The server verifies on-chain before responding.

Payment flow step by step

Deposit via Pix (4P Finance)

The primary way to fund an agent wallet is via Pix using 4P Finance, which converts BRL to USDC on Solana.

Plans

Metera plans control how many proxy endpoints and agent wallets you can create, and which analytics features are available. All plans include the core x402 payment functionality.

API reference — Authentication

All private API endpoints require a Bearer JWT in the Authorization header. You can obtain this from your session after signing in.

The agent proxy endpoints (/agent/:agentKey/*) and marketplace endpoints are public — authenticated by the agentKey UUID or no auth at all.

# Private endpoints
curl https://api.metera.xyz/api/agent-wallets \
  -H "Authorization: Bearer YOUR_JWT_TOKEN"

# Public endpoints — no auth
curl https://api.metera.xyz/agent/YOUR_AGENT_KEY/balance
curl https://api.metera.xyz/api/marketplace

Agent wallets endpoints

POST /api/agent-wallets — request body

{
  "name": "my-trading-bot",           // required
  "description": "Optional note",
  "network": "mainnet",               // default: "mainnet"
  "maxPerCall": 0.01,                 // USDC — null = no limit
  "maxPerHour": 1.00,
  "maxPerDay": 5.00,
  "maxPerMonth": 20.00,
  "allowedEndpoints": [],             // URL allowlist (empty = allow all)
  "blockedEndpoints": []              // URL blocklist
}

PATCH /api/agent-wallets/:id — updatable fields

{
  "name": "string",
  "description": "string",
  "maxPerCall": 0.05,
  "maxPerHour": 2.00,
  "maxPerDay": 10.00,
  "maxPerMonth": 50.00,
  "tier2ThresholdUsdc": 0.10,
  "tier3ThresholdUsdc": 1.00,
  "allowedEndpoints": ["https://api.example.com"],
  "blockedEndpoints": [],
  "isActive": true
}

Proxy endpoints

POST /api/proxy-endpoints — request body

{
  "name": "Weather API",              // required — slug is auto-generated
  "targetUrl": "https://api.openweathermap.org/data/2.5/weather", // required
  "description": "Current weather by city",
  "longDescription": "Extended markdown description",
  "category": "data",                 // default: "data"
  "pricePerCall": 0.001,              // USDC — default: 0.001
  "targetApiKey": "your-upstream-key", // injected server-side, never exposed
  "targetApiHeader": "x-api-key",    // default: "x-api-key"
  "isPublic": true,                  // default: true — lists in marketplace
  "methods": ["GET"],                // default: ["GET"]
  "tags": ["weather", "data"],
  "docsUrl": "https://openweathermap.org/api",
  "responseExample": "{ \"temp\": 22.5 }"
}

Calling a proxy endpoint as an agent

# Direct call — will get 402 if no payment
curl https://api.metera.xyz/p/weather-api

# Via the agent proxy (handles payment automatically)
curl -X POST https://api.metera.xyz/agent/YOUR_AGENT_KEY/fetch \
  -H "Content-Type: application/json" \
  -d '{ "url": "https://api.metera.xyz/p/weather-api", "method": "GET" }'

Marketplace endpoints

GET /api/marketplace — query params

Deposit endpoints

POST /api/deposit/fourp — request body

curl -X POST https://api.metera.xyz/api/deposit/fourp \
  -H "Authorization: Bearer YOUR_JWT" \
  -H "Content-Type: application/json" \
  -d '{
    "agentWalletId": "wallet-uuid",
    "amountBRL": 50,
    "cpf": "12345678901"
  }'

# Response
{
  "depositIntentId": "uuid",
  "pixCopiaECola": "00020126...",
  "expiresAt": "2026-06-26T14:00:00Z"
}

GET /api/deposit/status/:id — poll until completed

curl https://api.metera.xyz/api/deposit/status/DEPOSIT_INTENT_ID

# Response
{
  "status": "pending",   // or "completed" | "expired"
  "usdcAmount": null     // populated when completed
}

Agent proxy endpoints

These are public endpoints authenticated by the agentKey UUID. They are used by AI agents directly — not by your backend.

POST /agent/:agentKey/fetch — request body

curl -X POST https://api.metera.xyz/agent/YOUR_AGENT_KEY/fetch \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://api.metera.xyz/p/weather-api",
    "method": "GET",
    "headers": {},
    "body": null
  }'

# On success:
{ "status": 200, "data": { ... }, "paymentMade": true, "amountPaid": 0.001 }

# On tier 3 block:
{ "success": false, "code": "TIER3_APPROVAL_REQUIRED", "approvalId": "uuid" }

# On tier 2 rate block:
{ "success": false, "code": "TIER2_SOFT_BLOCK", "retryAfter": 60 }

GET /agent/:agentKey/balance

curl https://api.metera.xyz/agent/YOUR_AGENT_KEY/balance

{
  "walletAddress": "4Ui3P6mX...",
  "balance": { "usdc": "12.50", "currency": "USDC", "chain": "solana" },
  "stats": { "totalCalls": 142, "totalSpent": "0.142" }
}

Security overview

Metera is designed around a defense-in-depth model for AI agent spending. Multiple layers of enforcement prevent any single point of failure from draining an agent's wallet.

Squads Protocol v4

Squads Protocol v4 is the leading multisig and treasury management standard on Solana. Metera uses it to create a SpendingLimit PDA for each agent wallet on paid plans.

The SpendingLimit PDA enforces maxAutoApproveUsdc (your maxPerCall value) at the protocol level. No server-side code can bypass this limit — the blockchain rejects the transaction.

Setup happens automatically when you create a wallet on a paid plan. The multisig, vault, and spending limit PDAs are stored on the wallet record and visible in the dashboard.

3-tier spending governance

The tier router runs on every proxied call before any payment is made. See the Tier system section above for the full decision table.

Key security properties:

Anti-replay protection

Every USDC payment on Solana produces a unique transaction signature. Metera verifies that each signature corresponds to a real, confirmed, correctly-sized payment on-chain.

Solana's block hash mechanism means transaction signatures cannot be reused. Attempting to replay a transaction will fail at the network level before Metera even sees it.

FAQ