Courier

Shops block AI agents they can't verify. With no proof a person sent it, every agent order is a chargeback risk.

Courier gives your agent an ID. Give it a name and a color, connect it to Claude, ChatGPT or any MCP client, and ask for what you want with a budget. Shops see a client verified by PayPal, never your name, email or PayPal account. Limits are enforced in code before PayPal charges, never by a model.

It's standard MCP and OAuth 2.1: one connector reaches every shop, with no custom client.

Built for the PayPal AI Hackathon.

Try it

You need Node 24 or newer. No keys or accounts are required.

git clone https://github.com/Djbrl/courier.git
cd courier
npm install
npm run demo

Open http://localhost:4000 and click Try the demo. Demo mode uses a clearly labelled PayPal simulator, so no real accounts are involved.

To try the real flow with your own Claude and PayPal's test environment, use the hosted site. To test your own code changes that way, follow the local setup.

Related MCP server: AIShop4U

What it does

• Built on the PayPal you already trust. PayPal vouches you're real and pays. Courier gives your agent a pass, enforces your limit and coordinates group payments. The shop sees the courier and lets it in.

• Only you set the budget. The model can suggest a number, but can't confirm it. Save PayPal once, and purchases within your limits go through with no further steps.

• Shops get a pseudonym. Each shop gets its own shopper code, so two shops can't link the same person.

For shops: AI commerce, without the headaches

The shop desk (AG Studio) shows every order by courier and pseudonym, the access log, and a clerk built on PayPal's Agent Toolkit for refunds and tracking. Shops add Courier to their checkout with the Shops SDK for TypeScript and Python, generated with APIMatic.

Try to break it. Release the bots fires eight real attacks at a shop, including forged IDs, stolen tokens, overspending and prompt injection. They also run on every commit.

How it works

flowchart LR
    Person([You]) -- "write the ticket" --> Courier
    Agent[Claude] -- "OAuth 2.1" --> Courier
    Agent -- "MCP + signed ID" --> Shop
    Shop -- "may it spend this?" --> Courier
    Courier -- "verify, pay" --> PayPal

apps/courier      The authorization server, spend limits and your app
apps/store        20 demo shops, each with its own MCP server, and the shop desk
packages/shared   PayPal gateway, intent check, visa model, design system
tests             Unit tests, an end-to-end run, an official MCP client check

Docs

• Quickstart: what Courier does, what works today and what's next

• Code walkthrough: follow one purchase through the code, in about 15 minutes

• Architecture: the flows, the decisions and a glossary

• Live test: run it with the real PayPal sandbox and real Claude

• Contributing and Security

Status

Courier is a prototype. It only handles sandbox and simulated money.

• Working with real Claude and the PayPal sandbox: connecting, the ticket, paying through a PayPal link and paying with saved PayPal.

• Built and tested on the simulator, not yet on the sandbox: the $5 bond.

• Next: a way for real shops to sign up, PayPal partner onboarding so each sale lands in the shop's own account, and testing in more MCP clients.

License

MIT