> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xquik.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Machine Payments Protocol for X API billing

> Use HTTP 402 and Tempo USDC for anonymous fixed-price tweet, user, follow-check, article, trend, and community reads. Includes payment and receipt examples.

<blockquote className="agent-llms-directive">
  For the complete documentation index, see <a href="/llms.txt">llms.txt</a>.
</blockquote>

The [Machine Payments Protocol](https://mpp.dev) (MPP) is an open standard for machine-to-machine payments over HTTP. Xquik accepts direct MPP payments on fixed-price read operations. You can call them without an account, API key, or subscription.

## How it works

MPP uses HTTP 402 (Payment Required) as a payment challenge. When you call a direct MPP operation without authentication, the server returns an `application/problem+json` response and a `WWW-Authenticate: Payment` header. Your client pays through Tempo (USDC), then retries the request with a payment credential.

```text theme={null}
Client                              Xquik
  │                                   │
  │  1. GET /api/v1/x/tweets/123      │
  │──────────────────────────────────▶│
  │                                   │
  │  2. 402 Payment Required          │
  │     WWW-Authenticate: Payment     │
  │     (challenge with amount, etc.) │
  │◀──────────────────────────────────│
  │                                   │
  │  3. Pay via Tempo (USDC)          │
  │           (off-band)              │
  │                                   │
  │  4. Retry with credential         │
  │  Authorization: Payment proof     │
  │──────────────────────────────────▶│
  │                                   │
  │  5. HTTP response +               │
  │     Payment-Receipt               │
  │◀──────────────────────────────────│
```

<Note>
  Every response after an accepted payment includes `Payment-Receipt`, including non-2xx responses. The receipt confirms settlement, not application success. Challenges and rejected payment credentials do not include a receipt.
</Note>

The same `402` body also advertises an optional accountless guest wallet. The MPP challenge remains unchanged. A failed read creates no checkout. Create a hosted checkout only after the user confirms an amount.

You need no account, API key, or subscription. The payment credential authenticates the retried request.

## Payment method

MPP payments on Xquik use Tempo with USDC, a dollar-pegged stablecoin. Tempo provides the settlement method for these fixed charges.

You need a funded Tempo USDC wallet. See the [MPP quickstart](/mpp/quickstart) for setup instructions.

## Discovery

MPP discovery metadata is available at:

```text theme={null}
https://xquik.com/.well-known/mpp.json
```

The document points clients to the live OpenAPI spec and MPP overview page.

## Payment intent

All direct MPP operations use the `charge` intent. Each accepted payment settles the fixed price for one request. Xquik does not advertise direct MPP session pricing for result-sized pages.

## Eligible endpoints

| Endpoint | Method | Price | Intent |
| - | - | - | - |
| `/api/v1/x/tweets/{id}` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/tweets/{id}/translation` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/tweets/{id}/embed` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/users/{id}` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/spaces/{id}` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/spaces/{id}/replay` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/broadcasts/{id}` | GET | USD 0.00015 per call | charge |
| `/api/v1/x/followers/check` | GET | USD 0.00075 per call | charge |
| `/api/v1/x/articles/{tweetId}` | GET | USD 0.00075 per call | charge |
| `/api/v1/trends` | GET | USD 0.00045 per call | charge |
| `/api/v1/x/trends` | GET | USD 0.00045 per call | charge |
| `/api/v1/x/communities/{id}/info` | GET | USD 0.00015 per call | charge |

An accountless guest wallet covers the prepaid GET routes, including these. See the [guest paid-read route inventory](/guides/guest-wallets#eligible-paid-read-routes). Direct MPP payment credentials and guest keys cannot access monitors, webhooks, extractions, draws, writes, account routes, or account credential routes. API MCP cannot execute guest wallet credential routes.

## MPP vs subscription

<table>
  <caption className="sr-only">Compare MPP, guest wallet, and account access.</caption>

  <thead>
    <tr>
      <th scope="col">Capability</th>
      <th scope="col">MPP</th>
      <th scope="col">Guest wallet</th>
      <th scope="col">Account</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <th scope="row">Account required</th>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>

    <tr>
      <th scope="row">Credential</th>
      <td>Per-request payment credential</td>

      <td>
        <code>paid\_reads</code> API key
      </td>

      <td>Full API key or OAuth token</td>
    </tr>

    <tr>
      <th scope="row">Payment</th>
      <td>Per request via Tempo (USDC)</td>
      <td>USD 10 to 250 hosted checkout</td>
      <td>Available account credits. Plans add monthly credits.</td>
    </tr>

    <tr>
      <th scope="row">Available endpoints</th>
      <td>Fixed-price GET operations</td>
      <td>Prepaid GET routes</td>
      <td>Full account API</td>
    </tr>

    <tr>
      <th scope="row">Write actions</th>
      <td>Not available</td>
      <td>Not available</td>
      <td>Available with a connected X account</td>
    </tr>

    <tr>
      <th scope="row">Monitors, webhooks, extractions, and draws</th>
      <td>Not available</td>
      <td>Not available</td>
      <td>Available</td>
    </tr>

    <tr>
      <th scope="row">Best for</th>
      <td>Machine-paid requests</td>
      <td>Prepaid reads without an account</td>
      <td>Full platform workflows</td>
    </tr>
  </tbody>
</table>

## Next steps

<CardGroup cols={2}>
  <Card title="MPP quickstart" icon="rocket" href="/mpp/quickstart">
    Make your first pay-per-use API call.
  </Card>

  <Card title="Authentication" icon="key" href="/api-reference/authentication">
    Read every authentication method, including MPP headers.
  </Card>

  <Card title="Billing & usage" icon="credit-card" href="/guides/billing">
    Subscription, guest wallet, and direct MPP pricing.
  </Card>

  <Card title="Guest wallets" icon="wallet-cards" href="/guides/guest-wallets">
    Prepay accountless reads with one scoped API key.
  </Card>
</CardGroup>


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