Junto MCP Server

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.

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

Quick Start

npm install -g junto-mcp

Set your provider API key:

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

Run as CLI (human mode):

junto pay 25.00 maria@email.com
junto charge 10.00 "Coffee"
junto balance

Run as MCP server (for AI clients):

junto --mcp

Portuguese / Portugues

Junto auto-detects your system language, or set manually:

JUNTO_LANG=pt-BR junto ajuda
junto pagar 25.00 maria@email.com
junto cobrar 10.00 "Cafe"
junto saldo

See CLI.md for the full command reference in both languages.

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).

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

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, 8