> ## Documentation Index > Fetch the complete documentation index at: https://docs.hologram.io/llms.txt > Use this file to discover all available pages before exploring further. # Send cloud message to device > Send a cloud message (data) to one or more devices. Messages can be sent as plain text using the `data` parameter or as base64-encoded content using the `base64data` parameter. Port must be between 1 and 65535. Protocol must be TCP or UDP. Max data size is 10K. ## OpenAPI ````yaml /api/1/openapi.yaml post /devices/messages openapi: 3.0.0 info: title: Hologram REST API v1 description: >- The Hologram HTTP API is a REST-style interface for managing Hologram devices, accounts, and cloud data. Using the Hologram REST API, you can activate SIMs, get your devices approximate location, send SMS to your devices, update a device's usage limit, and much more. ## Authentication Hologram supports **HTTP Basic authentication** using API keys. Simply set the username of the request to `apikey`. The password field is the API key itself. You can find your API key on the Hologram Dashboard under [Account Settings](https://dashboard.hologram.io/settings/api). Your API key gives you access to your personal account, as well as any organizations you are a member of. Make sure you don't store your API key in a publicly accessible place like GitHub. If you are a member of multiple organizations, many endpoints accept an `orgid` argument to filter for devices or other objects within a specific organization. You can find your `orgid` by following [this guide from our Help Center](https://support.hologram.io/hc/en-us/articles/360035421234-What-is-my-organization-ID-orgid). ### Header Example ``` curl --verbose GET \ 'https://dashboard.hologram.io/api/1/users/me' \ -u apikey:YOUR_API_KEY ``` You can also base64 encode "apikey:YOUR_API_KEY" and include it directly in the header. ``` curl --verbose GET \ 'https://dashboard.hologram.io/api/1/users/me' \ --header "Authorization: Basic BASE64(apikey:YOUR_API_KEY)" ``` ## Requests Request bodies can be provided in either JSON or form-urlencoded formats. Please note that the examples in this documentation will only display JSON bodies. ### **JSON body** ``` curl --verbose --request POST \ --header "Content-Type: application/json" \ --header "Authorization: Basic BASE64(apikey:YOUR_API_KEY)" \ --data '{"deviceid": 56668, "body": "Hello device!"}' \ 'https://dashboard.hologram.io/api/1/sms/incoming' ``` ### **form-urlencoded body** ``` curl --verbose --request POST \ --header "Content-Type: application/x-form-urlencoded" \ --header "Authorization: Basic BASE64(apikey:YOUR_API_KEY)" \ --data 'deviceid=56668&body=Hello%20device!' \ 'https://dashboard.hologram.io/api/1/sms/incoming' ``` ## Responses All API responses are returned as JSON objects with the following fields: * `success` (boolean) - Indicates whether the request was successful. * `data` (object or array) - Contains the requested data or information about the operation that was performed. Only present when `success` is true. * `error` (string) - Information about why the request failed. Only present when `success` is false. Most GET responses will also include the following fields if a limit is included as part of the query string: * `limit` (number) - The query limit, some have this value built in and others often have a maximum value that the limit can be * `size` (number) - The number of values returned by the query * `continues` (boolean, optional) - This is only returned if there are more values than were returned * `links` (array) - Contains information related to the query performed * `path` (string) - The API endpoint path * `base` (string) - API base URL * `next` (string) - URL with query string to get the next results Note that all dates and times are returned in UTC. ## Rate Limiting In order to provide a good quality of service to all of our customers, we enforce a rate limit on all API requests. If you exceed the rate limit you will receive a HTTP 429 response with a JSON response body like this: ``` { "success":false, "error":"API rate limit exceeded" } ``` If you receive this response, you should refrain from making requests for 5-10 seconds and then retry the request. Hologram's REST API provides methods to perform many requests in bulk. For example, you can change the data plans of multiple SIMs at once using https://dashboard.hologram.io/api/1/links/cellular/changeplan. If there is request you would like to make in bulk but cannot, please reach out to [support@hologram.io](mailto:support@hologram.io) for assistance. version: '1' servers: - url: https://dashboard.hologram.io/api/1 description: Hologram REST API v1 security: [] tags: - name: Devices description: Devices - name: SIM Configuration description: SIM Configuration x-group: SIM Configuration - Conductor - name: Organizations description: Organizations - name: Personal account description: Personal account - name: Async Change Requests description: Async Change Requests paths: /devices/messages: post: tags: - Devices summary: Send cloud message to device description: >- Send a cloud message (data) to one or more devices. Messages can be sent as plain text using the `data` parameter or as base64-encoded content using the `base64data` parameter. Port must be between 1 and 65535. Protocol must be TCP or UDP. Max data size is 10K. operationId: postDeviceMessage requestBody: required: true content: application/json: schema: required: - deviceids - port - protocol properties: deviceids: description: List of device IDs to send the message to type: array items: type: integer port: description: Destination port number (1–65535) type: integer maximum: 65535 minimum: 1 protocol: description: Transport protocol for the message type: string enum: - TCP - UDP data: description: Data to send (plain text). Max 10K type: string base64data: description: Data to send encoded in base64. Max 10K type: string encrypted: description: When true (default), encrypt the message payload type: boolean default: true type: object responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/PostDeviceMessageResponse' '400': description: Bad request '401': description: Unauthorized security: - apiKeyAuth: [] components: schemas: PostDeviceMessageResponse: properties: success: $ref: '#/components/schemas/SuccessProperty' data: description: One entry per device the message was queued for type: array items: $ref: '#/components/schemas/PostDeviceMessageResult' type: object SuccessProperty: description: Indicates whether the request was successful. type: boolean example: true PostDeviceMessageResult: properties: deviceid: description: Device ID the message was sent to type: integer messageid: description: UUID assigned to the queued message type: string type: object securitySchemes: apiKeyAuth: type: http description: >- HTTP Basic authentication using API keys. Set the username to `apikey` and the password to your API key. You can find your API key on the Hologram Dashboard under Account Settings. scheme: basic ````