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docs/develop/integrate/slash-commands/index.md

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+---
+title: "Slash commands"
+sidebar_position: 30
+---
+
+Slash commands are messages that begin with `/` and trigger an HTTP request to a web service that can in turn post one or more messages in response.
+
+Slash commands have an additional feature, **autocomplete**, that displays a list of possible commands based on what has been typed in the message box. Typing `/` in an empty message box will display a list of all slash commands. As the slash command is typed in the message box, autocomplete will also display possible arguments and flags for the command.
+
+Unlike [outgoing webhooks](/developers/integrate/webhooks/outgoing), slash commands work in private channels and direct messages in addition to public channels, and can be configured to auto-complete when typing.
+Mattermost includes a number of [built-in slash commands](https://docs.mattermost.com/channels/interact-with-channels.html). You can also create [custom slash commands](/custom).
+
+## Tips and best practices
+
+1. Slash commands are designed to easily allow you to post messages. For other actions such as channel creation, you must also use the [Mattermost APIs](https://api.mattermost.com).
+2. Posts size is limited to 16383 characters for servers running [Mattermost Server v5.0 or later](https://docs.mattermost.com/administration/important-upgrade-notes.html). Use the `extra_responses` field to reply to a triggered slash command with more than one post.
+3. You can restrict who can create slash commands in [System Console > Integrations > Integration Management](https://docs.mattermost.com/configure/configuration-settings.html#enable-custom-slash-commands).
+4. Mattermost [outgoing webhooks](/developers/integrate/webhooks/outgoing) are Slack-compatible. You can copy-and-paste code used for a Slack outgoing webhook to create Mattermost integrations. Mattermost [automatically translates Slack's proprietary JSON payload format](/slack#translate-slacks-data-format-to-mattermost).
+5. The external application may be written in any programming language. It needs to provide a URL which receives the request sent by your Mattermost Server and responds with in the required JSON format.
+
+## FAQ
+
+### How do I debug slash commands?
+
+To debug slash commands in **System Console > Logs**, set **System Console > Logging > Enable Webhook Debugging** to **true** and set **System Console > Logging > Console Log Level** to **DEBUG**.
+
+### How do I send multiple responses from a slash command?
+
+You can send multiple responses with an `extra_responses` parameter as follows.
+
+```http
+HTTP/1.1 200 OK
+Content-Type: application/json
+Content-Length: 696
+
+```
+
+### What if my slash command takes time to build a response?
+
+Reply immediately with an `ephemeral` message to confirm response of the command, and then use the `response_url` to send up to five additional messages within a 30-minute time period from the original command invocation.
+
+### Why does my slash command fail to connect to `localhost`?
+
+By default, Mattermost prohibits outgoing connections that resolve to certain common IP ranges, including the loopback (`127.0.0.0/8`) and various private-use subnets.
+
+During development, you may override this behaviour by setting `ServiceSettings.AllowedUntrustedInternalConnections` to `"127.0.0.0/8"` in your `config.json` or via **System Console > Advanced > Developer**. See the [configuration settings documentation](https://docs.mattermost.com/configure/environment-configuration-settings.html#allow-untrusted-internal-connections) for more details.
+
+### Should I configure my slash command to use `POST` or `GET`?
+
+Best practice suggests using `GET` only if a request is considered idempotent. This means that the request can be repeated safely and can be expected to return the same response for a given input. Some servers hosting your slash command may also impose a limit to the amount of data passed through the query string of a `GET` request.
+
+Ultimately, however, the choice is yours. If in doubt, configure your slash command to use a `POST` request.
+
+
+<Note title="Mattermost releases prior to 5.0.0">
+Note that slash commands configured to use a <code>GET</code> request were broken prior to Mattermost release 5.0.0. The payload was incorrectly encoded in the body of the <code>GET</code> request instead of in the query string. While it was still technically possible to extract the payload, this was non-standard and broke some development stacks.
+</Note>
+
+
+### Why does my slash command always fail with `returned an empty response`?
+
+If you are emitting the `Content-Type: application/json` header, your body must be valid JSON. Any JSON decoding failure will result in this error message.
+
+Also, you must provide a `response_type`. Mattermost does not assume a default if this field is missing.
+
+### Why does my slash command print the JSON data instead of formatting it?
+
+Ensure you are emitting the `Content-Type: application/json` header, otherwise your body will be treated as plain text and posted as such.
+
+### Are slash commands Slack-compatible?
+
+See the [Slack compatibility](/slack) page.
+
+### How do I use Bot Accounts to reply to slash commands?
+
+#### If you are developing an integration
+- Set up a [Personal Access Token](/developers/integrate/reference/personal-access-token) for the Bot Account you want to reply with.
+- Use the [REST API](https://api.mattermost.com/#tag/posts/operation/CreatePost) to create a post with the Access Token.
+
+#### If you are developing a plugin
+
+Use [`CreatePost`](/developers/integrate/reference/server#API.CreatePost) plugin API. Make sure to set the  `UserId` of the post to the `UserId` of the Bot Account. If you want to create an ephemeral post, use [`SendEphemeralPost`](/developers/integrate/reference/server#API.SendEphemeralPost) plugin API instead.
+
+## Troubleshoot slash commands
+
+Join the [Mattermost user community](https://mattermost.com/pl/default-ask-mattermost-community) for help troubleshooting your slash command.
+
+## Share your integration
+
+If you've built an integration for Mattermost, please consider [sharing your work](/developers/integrate/getting-started) in our [Marketplace](https://mattermost.com/marketplace/).
+
+The [Marketplace](https://mattermost.com/marketplace/) lists open source integrations developed by the Mattermost community and are available for download, customization, and deployment to your private cloud or self-hosted infrastructure.
+### Are slash commands Slack-compatible?
+
+See the [Slack compatibility](/slack) page.
+
+### How do I use Bot Accounts to reply to slash commands?
+
+#### If you are developing an integration
+- Set up a [Personal Access Token](/developers/integrate/reference/personal-access-token) for the Bot Account you want to reply with.
+- Use the [REST API](https://api.mattermost.com/#tag/posts/operation/CreatePost) to create a post with the Access Token.
+
+#### If you are developing a plugin
+
+Use [`CreatePost`](/developers/integrate/reference/server#API.CreatePost) plugin API. Make sure to set the  `UserId` of the post to the `UserId` of the Bot Account. If you want to create an ephemeral post, use [`SendEphemeralPost`](/developers/integrate/reference/server#API.SendEphemeralPost) plugin API instead.
+
+## Troubleshoot slash commands
+
+Join the [Mattermost user community](https://mattermost.com/pl/default-ask-mattermost-community) for help troubleshooting your slash command.
+
+## Share your integration
+
+If you've built an integration for Mattermost, please consider [sharing your work](/developers/integrate/getting-started) in our [Marketplace](https://mattermost.com/marketplace/).
+
+The [Marketplace](https://mattermost.com/marketplace/) lists open source integrations developed by the Mattermost community and are available for download, customization, and deployment to your private cloud or self-hosted infrastructure.