> ## Documentation Index > Fetch the complete documentation index at: https://docs.social-api.ai/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Base URL: https://api.social-api.ai/v1. Send your API key in the Authorization header: Authorization: Bearer . > Every error response from /v1 is JSON: { "error": { "code", "message", "meta" (optional) }, "request_id" }. Branch on error.code; use error.message only for logs. > A 429 response carries a Retry-After header, in seconds, when the limit has a known wait. Authenticated responses can carry X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset for the per-minute request budget your SocialAPI account shares across every API key (see /guides/rate-limits). > Paginated list endpoints return next_cursor, at the top level or inside pagination (see /guides/pagination). Pass it as the cursor query parameter to get the next page. An absent or empty next_cursor means you have the last page. > Treat every ID as an opaque string: do not parse it or assume a format. > Support differs by platform and by operation. Check /platforms/overview before assuming an operation works on a platform. An unsupported operation returns 501 with error.code resource.not_supported. # Send a private reply to a commenter > Sends a direct message to the author of a comment. Only supported on Instagram and Facebook. Meta allows one private reply per comment, within 7 days of the comment; a second attempt or an expired window returns HTTP 400 with error code platform.instagram.private_reply_ineligible or platform.facebook.private_reply_ineligible. Once a comment has spent its one reply, or the comment is older than 7 days, further attempts are refused and do not count against your outbound message rate; the error carries a reason of already_replied, platform_refused or window_expired. The 400 is terminal: retrying it will never succeed. Set buttons (1 to 3) to send the reply as a button template with text as its body; a tap on a postback button arrives as a dm.postback event. Set attachment instead of text to send one image, video, audio or file: a private reply is a single message, so it carries either text (with optional buttons) or one attachment, never both. You cannot message the commenter again until they respond; once they do, the conversation continues within the standard 24-hour messaging window. Check the can_private_reply capability flag. ## OpenAPI ````yaml /api-reference/openapi.json post /inbox/comments/{postId}/{commentId}/private-reply openapi: 3.0.0 info: description: >- Unified social media inbox API. Read and respond to comments, DMs, reviews, and mentions across Instagram, Facebook, Threads, Google Business Profile, TikTok, LinkedIn, and YouTube through a single REST API. X/Twitter and Trustpilot coming soon. title: SocialAPI.AI contact: name: SocialAPI.AI Support email: support@social-api.ai license: name: MIT version: '1.0' servers: - url: https://api.social-api.ai/v1 security: [] paths: /inbox/comments/{postId}/{commentId}/private-reply: post: tags: - Inbox Comments summary: Send a private reply to a commenter description: >- Sends a direct message to the author of a comment. Only supported on Instagram and Facebook. Meta allows one private reply per comment, within 7 days of the comment; a second attempt or an expired window returns HTTP 400 with error code platform.instagram.private_reply_ineligible or platform.facebook.private_reply_ineligible. Once a comment has spent its one reply, or the comment is older than 7 days, further attempts are refused and do not count against your outbound message rate; the error carries a reason of already_replied, platform_refused or window_expired. The 400 is terminal: retrying it will never succeed. Set buttons (1 to 3) to send the reply as a button template with text as its body; a tap on a postback button arrives as a dm.postback event. Set attachment instead of text to send one image, video, audio or file: a private reply is a single message, so it carries either text (with optional buttons) or one attachment, never both. You cannot message the commenter again until they respond; once they do, the conversation continues within the standard 24-hour messaging window. Check the can_private_reply capability flag. parameters: - example: '17895695668004550' description: Platform post ID name: postId in: path required: true schema: type: string - example: '17858893269577012' description: Platform comment ID name: commentId in: path required: true schema: type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/api_endpoints.PrivateReplyRequest' description: Private reply content required: true responses: '200': description: Private reply sent content: application/json: schema: $ref: '#/components/schemas/api_endpoints.SuccessResponse' '400': description: >- Missing required fields, attachment combined with text or buttons (validation.attachment_conflict), or comment not eligible for a private reply (platform.instagram.private_reply_ineligible, platform.facebook.private_reply_ineligible) content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' '401': description: Invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' '403': description: The key's scopes do not include inbox:write content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' '404': description: Account not found content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' '422': description: >- The platform could not fetch or accept the attachment (platform.instagram.attachment_failed, platform.facebook.attachment_failed). The comment can still receive a private reply: fix the URL or file and send again content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' '501': description: Platform does not support private replies content: application/json: schema: $ref: '#/components/schemas/api_endpoints.ErrorResponse' security: - BearerAuth: [] components: schemas: api_endpoints.PrivateReplyRequest: type: object properties: account_id: type: string attachment: description: >- Attachment sends one image, video, audio or file as the private reply, instead of text. Leave text and buttons empty when you set it. allOf: - $ref: '#/components/schemas/api_endpoints.PrivateReplyAttachmentInput' buttons: description: >- Buttons renders a button template (1-3 buttons); uses text as the bubble body. type: array items: $ref: '#/components/schemas/api_endpoints.MessageButton' text: type: string api_endpoints.SuccessResponse: type: object properties: success: type: boolean example: true api_endpoints.ErrorResponse: type: object properties: error: $ref: '#/components/schemas/api_endpoints.ErrorBody' request_id: description: >- RequestID matches the X-Request-ID response header. Include it when contacting support. type: string example: 01HZ9X3Q4R5M6N7P8V2K0W1J api_endpoints.PrivateReplyAttachmentInput: type: object properties: source: description: >- Source is the attachment reference; its meaning is given by source_type. type: string example: https://cdn.example.com/guide.pdf source_type: description: |- SourceType selects how Source is interpreted: - "url": Source is a publicly reachable media URL the platform fetches directly. - "media_id": Source is a file id in your SocialAPI media library (GET /v1/media). - "platform_attachment_id": Source is an id of media already uploaded to the target platform (for example a Meta attachment_id). type: string enum: - url - media_id - platform_attachment_id example: url type: description: >- Type is the media kind. Optional for url and media_id sources (inferred from the file), required for platform_attachment_id. type: string enum: - image - video - audio - file example: file api_endpoints.MessageButton: type: object properties: payload: type: string example: VIEW_ORDER title: type: string example: View order type: type: string enum: - url - postback example: url url: type: string example: https://shop.example.com/orders/1 api_endpoints.ErrorBody: type: object properties: code: type: string example: resource.not_found message: type: string example: Account not found meta: type: object additionalProperties: {} securitySchemes: BearerAuth: description: >- Prefix your API key with "Bearer ". Example: `Authorization: Bearer sapi_key_...` type: apiKey name: Authorization in: header ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.