obol

Pay the ferryman. Solana agent gateway via x402.

Obol is a pay-per-use Solana API for AI agents. No API keys, no subscriptions — agents pay per request in USDC using the x402 payment protocol. Solana's sub-cent transaction costs make micropayments viable for the first time.

Named after the coin placed on the tongue of the dead to pay Charon for passage across the River Styx. The original micropayment.

How it works

1. Agent requests data from a paid endpoint

2. Obol returns HTTP 402 with a payment requirement (amount, recipient, network)

3. Agent sends USDC on Solana matching the requirement

4. Agent retries with transaction proof in the X-PAYMENT header

5. Obol verifies on-chain and returns the data

No accounts. No tokens. No onboarding. Just pay and go.

Related MCP server: boo-x402-mcp

Endpoints

Wallet Analytics

Token Data

DeFi

Free

Agent Example

See examples/agent-client.ts for a full reference implementation. The key flow:

import { ObolAgent } from './examples/agent-client';

const agent = new ObolAgent();
await agent.discover();  // fetch pricing
agent.loadWallet(process.env.AGENT_PRIVATE_KEY);

// Auto-discovers price, pays, and returns data
const price = await agent.fetch('/api/v1/token/USDC_MINT/price');

Run in discovery-only mode (no wallet needed):

npx tsx examples/agent-client.ts

MCP Server

Obol ships as an MCP server — any AI agent that supports the Model Context Protocol can discover and call Obol's tools natively.

Install from npm

npm install -g obol-mcp

Claude Desktop / Claude Code

Add to your MCP config:

{
  "mcpServers": {
    "obol": {
      "command": "npx",
      "args": ["-y", "obol-mcp"],
      "env": {
        "OBOL_URL": "https://obol-production.up.railway.app"
      }
    }
  }
}

Or if developing locally:

{
  "mcpServers": {
    "obol": {
      "command": "npx",
      "args": ["tsx", "/path/to/obol/src/mcp.ts"],
      "env": {
        "OBOL_URL": "http://localhost:3000"
      }
    }
  }
}

Available MCP Tools

Run locally

npm run mcp

Stack

• Fastify 5 — high-performance HTTP

• @x402/svm — official x402 SDK for Solana

• Helius — RPC + DAS API

• Jupiter — token prices + swap execution

• Upstash Redis — cache + payment receipts

• TypeScript — full type safety

• Zod — runtime validation

Setup

git clone https://github.com/halfkey/obol.git
cd obol
npm install
cp .env.example .env
# Edit .env with your Helius key and merchant wallet address
npm run dev

Testing

# Unit + integration tests (46 tests)
npm test -- --run

# Smoke test against live deployment
npx tsx scripts/smoke-test.ts https://obol-production.up.railway.app

# Manual payment test
npx tsx scripts/test-payment.ts <tx-signature>

Environment

See .env.example. Key variables:

• PAYMENT_MODE — mock (dev, auto-approve) or onchain (production)

• PAYMENT_RECIPIENT_ADDRESS — your Solana wallet that receives USDC

• HELIUS_API_KEY — Helius RPC access

• UPSTASH_REDIS_REST_URL / TOKEN — cache layer

Roadmap

• 11 paid endpoints (wallet, token, DeFi, LST, P&L)

• On-chain USDC verification with replay prevention

• Test suite (46 vitest + 20-point smoke test)

• Agent client reference implementation

• GitHub Actions CI

• WebSocket subscriptions for wallet monitoring

• Dynamic congestion-based pricing

• Multi-chain support

License

MIT