Junto

> The payment protocol for people and agents.

Send and receive money through any AI assistant. Any payment rail. Built-in guardrails.

Named after Benjamin Franklin's Junto) — a society of tradesmen who built civic infrastructure together. Different providers, same table, mutual benefit.

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Why

AI assistants are starting to move real money — paying invoices, splitting bills, sending transfers. But every payment provider has a different API, different auth, different settlement times. Nobody should have to teach their assistant how Pix works vs Stripe vs Wise.

Junto fixes that with one MCP server that:

- Exposes a universal payment toolkit to any MCP-compatible client (Claude, Cursor, custom agents)
- Routes to the right provider based on currency, country, and rail
- Enforces spending limits so agents can't go rogue
- Supports human-in-the-loop confirmation for high-value transactions
- Logs every action for audit and accountability

Tools

| Tool | Description |
|---|---|
| pay | Send money to a destination (Pix key, email, IBAN, etc.) |
| charge | Create a payment request / invoice / QR code |
| status | Check payment status by correlation ID |
| refund | Reverse a completed transaction |
| balance | Check available funds on a provider |
| providers | List configured providers and their capabilities |
| limits | Show spending limits and today's usage |

Quick Start

npm install -g junto-mcp

Set your provider API key:

export WOOVI_APP_ID="your-woovi-app-id"

Run:

junto-mcp

Add to Claude Desktop or Cursor

{
  "mcpServers": {
    "junto": {
      "command": "npx",
      "args": ["-y", "junto-mcp"],
      "env": {
        "WOOVI_APP_ID": "your-woovi-app-id"
      }
    }
  }
}

That's it. Your AI assistant now has payment tools.

Guardrails

All amounts are in cents (smallest currency unit).

| Setting | Env Var | Default | Meaning |
|---|---|---|---|
| Daily limit | JUNTO_DAILY_LIMIT | 50000 (R$500) | Max total spend per day |
| Per-tx max | JUNTO_PER_TX_MAX | 20000 (R$200) | Max single transaction |
| Confirm above | JUNTO_CONFIRM_ABOVE | 5000 (R$50) | Ask human before sending |
| Allowed providers | JUNTO_ALLOWED_PROVIDERS | _(all)_ | Comma-separated allowlist |
| Allowed destinations | JUNTO_ALLOWED_DESTINATIONS | _(all)_ | Comma-separated type allowlist |

When an agent tries to send above the JUNTO_CONFIRM_ABOVE threshold, the server pauses and returns a confirmation prompt. The agent must relay this to the user and get approval before proceeding.

⚠️ Confirmation required
Amount:      BRL 150.00

  To:          maria@email.com

  Reason:      Amount (15000 cents) exceeds confirmation threshold (5000 cents)
Please confirm with the user before proceeding.

Architecture

┌─────────────────────────────────────┐
│  MCP Client (Claude, Cursor, etc.)  │
└──────────────┬──────────────────────┘
               │ MCP Protocol (stdio)
┌──────────────▼──────────────────────┐
│           junto-mcp                 │
│                                     │
│  ┌───────────┐  ┌────────────────┐  │
│  │  Router    │  │  Guardrails    │  │
│  │  (picks    │  │  (spend caps,  │  │
│  │  provider) │  │  HITL confirm, │  │
│  │           │  │  audit log)    │  │
│  └─────┬─────┘  └────────────────┘  │
│        │                            │
│  ┌─────▼─────────────────────────┐  │
│  │  Provider Adapters            │  │
│  │  ┌────────┐ ┌──────┐ ┌────┐  │  │
│  │  │ Woovi  │ │Stripe│ │Wise│  │  │
│  │  └────────┘ └──────┘ └────┘  │  │
│  └───────────────────────────────┘  │
│                                     │
│  ┌───────────────────────────────┐  │
│  │  Audit Ledger (JSONL)         │  │
│  └───────────────────────────────┘  │
└─────────────────────────────────────┘

Providers

| Provider | Region | Rails | Status |
|---|---|---|---|
| Woovi/OpenPix | Brazil | Pix | 🟢 Shipped |
| Belvo | Brazil | Open Finance (all banks) | 🟡 Next |
| Stripe | Global | Cards, ACH, SEPA | 🟡 Next |
| Wise | Global | Bank transfers | 🔴 Planned |
| Mercado Pago | LATAM | Pix, Cards | 🔴 Planned |
| PayPal | Global | Email-based | 🔴 Planned |

Why Woovi/Pix first?

- Pix settles instantly (perfect for demos and real use)
- Brazil's Central Bank mandates open APIs for payments
- 180M+ Pix users, 80B+ transactions in 2025
- Pix Automático (launched June 2025) enables recurring payments
- Low fees, no intermediaries

Demo

You:   "Pay R$25 to maria@email.com via Pix"
Agent:  I'll send the following payment:

          Amount: R$ 25,00

          To: maria@email.com (Pix)

          Via: Woovi

        Shall I go ahead?
You:   "Yes"
Agent:  Done! Payment sent.

          Amount: R$ 25,00

          To: maria@email.com

          Via: Pix (Woovi)

          Status: Completed

          ID: junto-1739612345-a1b2c3

Adding a Provider

Each provider is a single file implementing the PaymentProvider interface:

// src/providers/your-provider.ts
import { PaymentProvider } from "../types.js";
export class YourProvider implements PaymentProvider {

  name = "your-provider";

  supportedCurrencies = ["USD"];

  supportedRails = ["card"];

  settlementTime = "1-3 days";
async pay(req) { / send money / }

  async charge(req) { / create invoice / }

  async status(id) { / check status / }

  async refund(id) { / reverse payment / }

  async balance() { / check funds / }

  info() { / return capabilities / }

}

Copy src/providers/_template.ts to get started, then register your provider in src/index.ts.

Testing

npm test

Runs guardrail tests covering: amount limits, daily budget tracking, confirmation thresholds, provider allowlists, and destination type filtering.

Audit Log

Every transaction is logged to ~/.junto/audit-YYYY-MM-DD.jsonl:

{
  "timestamp": "2026-02-15T14:32:07Z",
  "type": "payment",
  "action": "pay",
  "tool": "pay",
  "amount": 2500,
  "currency": "BRL",
  "provider": "woovi",
  "destination": "maria@email.com",
  "status": "executed"
}

Roadmap

- [x] Core MCP server with universal tool interface
- [x] Woovi/OpenPix provider (Pix)
- [x] Guardrails (daily limits, per-tx max, HITL confirmation)
- [x] Audit ledger
- [x] junto-skill (Claude behavioral layer)
- [ ] Belvo provider (Open Finance — all Brazilian banks)
- [ ] Stripe provider (Cards, ACH, SEPA)
- [ ] junto-approve (Telegram/WhatsApp confirmation for HITL)
- [ ] junto-dashboard (web UI for tx history and limits)
- [ ] junto-compute (agent-to-agent budget delegation)
- [ ] AP2 compatibility layer (Google Agent Payments Protocol)
- [ ] Wise provider (international bank transfers)

Contributing

We need help with:

- Provider adapters — Stripe, Wise, Belvo, Mercado Pago, PayPal, UPI
- Routing logic — Cheapest vs fastest vs most reliable provider selection
- HITL patterns — Approval flows across different MCP clients
- Security audit — Review of the guardrails and auth system
- Multi-currency — FX handling, cross-border routing
- Docs — Compliance and regulatory guides per region

License

MIT