Junto MCP

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

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, 80B+ transactions in 2025
• Pix Automático (launched June 2025) enables recurring payments
• Low fees, no intermediaries
• Verified: charge, status, and payment flows tested with real Pix transactions (March 2026)

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              # Guardrail unit tests

npm run test:smoke # Full flow smoke tests (mock provider)

Live testing with real Pix

# Create a Pix charge (R$1.00)

WOOVI_APP_ID=your-key npx tsx test/live-pix.ts charge 100 "Test charge"

Check status

WOOVI_APP_ID=your-key npx tsx test/live-pix.ts status

Send a Pix payment

WOOVI_APP_ID=your-key npx tsx test/live-pix.ts pay 100 user@email.com EMAIL

Refund

WOOVI_APP_ID=your-key npx tsx test/live-pix.ts refund

Interactive demo

npx tsx demo/demo.ts          # Full demo with typewriter narration + real API calls

npx tsx demo/demo.ts --fast # Fast mode for rehearsals

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

• Core MCP server with universal tool interface
• Woovi/OpenPix provider (Pix) — live-tested with real transactions
• Guardrails (daily limits, per-tx max, HITL confirmation)
• Audit ledger
• junto-skill (Claude behavioral layer)
• Interactive demo (npx tsx demo/demo.ts)
• Ebanx provider (Pix payouts, Boleto, Cards — Brazil + LATAM)
• 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 — Ebanx, 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