> ## Documentation Index
> Fetch the complete documentation index at: https://x-preview-oauth-2-ios.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Integration guide

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This page contains information on several tools and key concepts to help you integrate the Posts lookup endpoints into your system. We’ve organized the page into a few sections:

* [Helpful tools](#helpful)
* Key Concepts
  * [Authentication](#authentication)
  * [Developer portal, Projects, and Apps](#portal)
  * [Rate limits](#limits)
  * [Fields and expansions](#fields)
  * [Post edits](#edits)
  * [Edge cases](#edge)

## Helpful tools

Before we dive into some key concepts, we recommend familiarizing yourself with the following tools:

**Postman**\
Postman is an excellent tool to test out an endpoint, including every path and body parameter to help you understand what’s available. Check out our [getting started with Postman guide](/tutorials/postman-getting-started) to learn more.

**Code samples**\
Find code samples for your preferred programming language on our [Github page](https://github.com/xdevplatform/Twitter-API-v2-sample-code).

**Third-party libraries**\
Utilize community-built [third-party libraries](/resources/tools-and-libraries) compatible with v2 endpoints.

## Key Concepts

### Authentication

All X API v2 endpoints require authenticated requests. You can authenticate with either:

* [OAuth 1.0a User Context](/resources/fundamentals/authentication) using API Keys, Access Tokens, and additional parameters to [create an authorization header](/resources/fundamentals/authentication#authorizing-a-request).
* [OAuth 2.0 App-Only](/resources/fundamentals/authentication#oauth-2-0) by passing an [App Access Token](/resources/fundamentals/authentication) with your request.
* [OAuth 2.0 Authorization Code with PKCE](/resources/fundamentals/authentication) for greater control over app scope and multi-device authorization.

<Note>
  OAuth 1.0a can be challenging to implement. If unfamiliar, consider using a [library](/resources/tools-and-libraries) or OAuth 2.0 for requests. For private metrics or Posts, use OAuth 1.0a User Context or OAuth 2.0 Authorization Code with PKCE.
</Note>

<Tip>
  **Please note**

  > If you are requesting the following fields, OAuth 1.0a User Context or OAuth 2.0 Authorization Code is required:
  >
  > * `tweet.fields.non_public_metrics`
  > * `tweet.fields.promoted_metrics`
  > * `tweet.fields.organic_metrics`
  > * `media.fields.non_public_metrics`
  > * `media.fields.promoted_metrics`
  > * `media.fields.organic_metrics`
</Tip>

### Developer portal, Projects, and Apps

To obtain credentials for X API v2, you need:

1. An approved [developer account](/resources/fundamentals/developer-portal).
2. A [Project](/resources/fundamentals/projects) within the developer account.
3. A [developer App](/resources/fundamentals/developer-apps) within that Project, where keys and tokens can be found.

### Rate limits

X API requests are subject to [rate limits](/resources/fundamentals/rate-limits) to manage volume. Limits apply at both the App and user levels:

* **App-level**: Limits the number of requests made per period by any app.
* **User-level**: Limits how frequently an authenticated user can perform Post lookups across developer Apps.

### Fields and expansions

The X API v2 allows selection of specific data fields using `fields` and `expansions`:

* **Expansions**: Enable retrieval of additional related objects. Supported expansions include:
  * `edit_history_tweet_ids`
  * `attachments.poll_ids`
  * `attachments.media_keys`
  * `author_id`
  * `entities.mentions.username`
  * `geo.place_id`
  * `in_reply_to_user_id`
  * `referenced_tweets.id`
  * `referenced_tweets.id.author_id`

* **Fields**: Specify data fields within objects to return additional data. The Post object defaults to `id`, `text`, and `edit_history_tweet_ids`. Other options, like `tweet.created_at` and `tweet.entities`, must be explicitly requested.

For more, refer to the fields and expansions guide in the [X API v2 data dictionary](/x-api/fundamentals/data-dictionary).

### Post edits

Eligible Posts can be edited up to five times within 30 minutes of publishing. The Posts lookup endpoint always provides the latest Post version. For near-real-time use cases, be aware of this time window. For more details, see [Edit Posts fundamentals](/x-api/fundamentals/edit-posts).

### Edge cases

* **Promoted metrics**: Requesting promoted metrics for non-promoted Posts returns an empty response.
* **Truncated text**: Post text is truncated for Retweets. To retrieve full text, expand the referenced Post