> ## 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

> Anonymous pay-per-use access to X data endpoints via HTTP 402 and Tempo (USDC)

<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 implements MPP on 32 X-API read-only endpoints, allowing you to pay per call without creating an account or subscribing.

## How it works

MPP uses HTTP 402 (Payment Required) as a payment challenge. When you call an eligible endpoint without a subscription or API key, the server returns a 402 with payment instructions. Your client pays via 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 ...    │
  │──────────────────────────────────▶│
  │                                   │
  │  5. 200 OK +                      │
  │     Payment-Receipt               │
  │◀──────────────────────────────────│
```

<Note>
  For both charge and session intents, the `Payment-Receipt` header is included only on successful 2xx responses after payment is accepted. Error responses use the status code and response body without a receipt header.
</Note>

No account, no API key, no subscription. The payment itself is your authentication.

## Payment method

MPP payments on Xquik use **Tempo** with USDC (a dollar-pegged stablecoin). Tempo provides near-zero transaction fees, making micropayments practical for per-call pricing.

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 intents

Xquik uses 2 payment intents depending on the endpoint:

| Intent    | How it works                                                                       | Used by                                                                                                                                                                                                                                                                      |
| --------- | ---------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `charge`  | Fixed cost per call. Single on-chain settlement.                                   | Tweet lookup, user lookup, follower check, article extraction, trends, community info                                                                                                                                                                                        |
| `session` | Pay per result returned. Client deposits funds, sends off-chain vouchers per item. | Tweet search, user tweets, user replies, quotes, replies, retweeters, favoriters, thread, likes, user media, community members/moderators/tweets/search, list followers/members/tweets, user batch/search/followers/following/mentions/verified-followers/followers-you-know |

With `charge`, you pay a flat amount per request. With `session`, you pay proportional to the number of results returned.

## Eligible endpoints

| Endpoint                                  | Method | Price                     | Intent  |
| ----------------------------------------- | ------ | ------------------------- | ------- |
| `/api/v1/x/tweets/{id}`                   | GET    | USD 0.00015 per call      | charge  |
| `/api/v1/x/tweets/search`                 | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/{id}`                    | GET    | USD 0.00015 per call      | charge  |
| `/api/v1/x/followers/check`               | GET    | USD 0.00105 per call      | charge  |
| `/api/v1/x/articles/{tweetId}`            | GET    | USD 0.00105 per call      | charge  |
| `/api/v1/x/users/{id}/tweets`             | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/{id}/replies`            | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/tweets/{id}/quotes`            | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/tweets/{id}/replies`           | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/tweets/{id}/retweeters`        | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/tweets/{id}/favoriters`        | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/tweets/{id}/thread`            | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/{id}/likes`              | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/{id}/media`              | GET    | USD 0.00015 per tweet     | session |
| `/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  |
| `/api/v1/x/communities/{id}/members`      | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/communities/{id}/moderators`   | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/communities/{id}/tweets`       | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/communities/search`            | GET    | USD 0.00015 per community | session |
| `/api/v1/x/communities/tweets`            | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/lists/{id}/followers`          | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/lists/{id}/members`            | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/lists/{id}/tweets`             | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/batch`                   | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/users/search`                  | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/users/{id}/followers`          | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/users/{id}/followers-you-know` | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/users/{id}/following`          | GET    | USD 0.00015 per user      | session |
| `/api/v1/x/users/{id}/mentions`           | GET    | USD 0.00015 per tweet     | session |
| `/api/v1/x/users/{id}/verified-followers` | GET    | USD 0.00015 per user      | session |

All other endpoints (monitors, webhooks, extractions, draws, write actions, etc.) require a [subscription](/guides/billing).

## MPP vs subscription

|                         | MPP (pay-per-use)                            | Subscription (USD 20/month)                             |
| ----------------------- | -------------------------------------------- | ------------------------------------------------------- |
| **Account required**    | No                                           | Yes                                                     |
| **API key required**    | No                                           | Yes                                                     |
| **Payment**             | Per call via Tempo (USDC)                    | Monthly credit/debit card                               |
| **Available endpoints** | 32 X-API read-only                           | All endpoints                                           |
| **Write actions**       | Not available                                | Post tweets, like, retweet, follow, DM, profile updates |
| **Monitors & webhooks** | Not available                                | Real-time account monitoring                            |
| **Extractions & draws** | Not available                                | Bulk data extraction, giveaway draws                    |
| **Best for**            | AI agents, one-off lookups, low-volume reads | Full platform access, production integrations           |

## Next steps

<CardGroup cols={3}>
  <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">
    All authentication methods including MPP headers.
  </Card>

  <Card title="Billing & usage" icon="credit-card" href="/guides/billing">
    Subscription pricing and MPP per-call costs.
  </Card>
</CardGroup>