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# Ruby SDK \[The mpp-rb library]

## Overview

The `mpp-rb` Ruby gem provides a typed interface over the Machine Payments Protocol, from high-level abstractions to low-level primitives and building blocks.

<div className="flex gap-2">
  [GitHub: stripe/mpp-rb](https://github.com/stripe/mpp-rb)

  Maintained by [Stripe](https://github.com/stripe)
</div>

## Install

```bash [install.sh]
$ gem install mpp-rb
```

Or add to your Gemfile:

```ruby [Gemfile]
gem "mpp-rb"
```

## Requirements

* Ruby 3.3+
* `eth` for Tempo signing (optional)
* `stripe` for Stripe method (optional)
* `async` + `async-http` for async HTTP (optional)

## Quick start

### Server

```ruby [server.rb]
require "mpp-rb"

server = Mpp.create(
  method: Mpp::Methods::Tempo.tempo(
    currency: "0x20c0000000000000000000000000000000000000",
    intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new },
    recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
  ),
  secret_key: ENV["MPP_SECRET_KEY"],
)

# In your request handler
result = server.charge(
  request.get_header("HTTP_AUTHORIZATION"),
  "0.50",
  description: "Paid resource",
)

if result.is_a?(Mpp::Challenge)
  resp = Mpp::Server::Decorator.make_challenge_response(result, server.realm)
  [resp["status"], resp["headers"], [resp["body"]]]
else
  credential, receipt = result
  [200, { "Payment-Receipt" => receipt.to_payment_receipt }, [{ data: "paid content", payer: credential.source }.to_json]]
end
```

Set `MPP_SECRET_KEY` in your environment before you start the server, or pass `secret_key` explicitly to `Mpp.create()`.

## Client

```ruby [client.rb]
require "mpp-rb"

account = Mpp::Methods::Tempo::Account.from_env

transport = Mpp::Client::Transport.new(
  methods: [Mpp::Methods::Tempo.tempo(account: account)],
)

response = transport.get("https://mpp.dev/api/ping/paid")
puts response.body
```

## Module layout

| Module | Description |
|--------|-------------|
| `Mpp::Challenge` | Challenge parsed from `WWW-Authenticate` |
| `Mpp::Credential` | Credential for the `Authorization` header |
| `Mpp::Receipt` | Receipt parsed from `Payment-Receipt` |
| `Mpp::Client::Transport` | HTTP client with automatic `402` handling |
| `Mpp::Server::Middleware` | Rack middleware for payment-gated endpoints |
| `Mpp::Methods::Tempo` | Tempo payment method (client and server) |
| `Mpp::Methods::Stripe` | Stripe payment method (client and server) |

## Next steps

[Core types](/sdk/ruby/core) — Challenge, Credential, Receipt types

[Client](/sdk/ruby/client) — Handle 402 responses automatically

[Server](/sdk/ruby/server) — Protect endpoints with payments