Multi-Platform Post API

When to use it

• You already have video files and just need distribution — this is the post-only endpoint without generation.
• Bulk-uploading a library of pre-produced content.
• Recurring scheduled distribution (daily/weekly digests, news broadcasts, etc.).
• Building a Buffer/Hootsuite alternative as a feature inside your own product.

To generate and post in one call, use Generate & Post instead.

Endpoints

• POST /api/v1/post — Post a video to one or more platforms immediately
• POST /api/v1/schedules — Create a recurring schedule (daily/weekly/cron)
• GET /api/v1/schedules — List your schedules
• DELETE /api/v1/schedules/{schedule_id} — Cancel a schedule
• GET /api/v1/social-accounts — List linked accounts + token freshness

Prerequisites

Before posting, your end-user must connect their social accounts via OAuth. Connections live in the dashboard at /dashboard/v5/social-accounts.

For multi-tenant integrations (you posting on behalf of your users), use the user-impersonation flow:

1. Send your user to https://reelsbuilder.ai/social/connect?platform=tiktok&return_url=...
2. They authorize once.
3. Their user_id shows in GET /api/v1/social-accounts.
4. Pass target_user_id in your post requests to attribute the post to them.

Quickstart — post immediately

curl -X POST https://api.reelsbuilder.ai/api/v1/post \
  -H "Authorization: Bearer $REELSBUILDER_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://your-cdn.example.com/clip.mp4",
    "platforms": ["tiktok", "instagram", "youtube_shorts"],
    "caption": "Why we ship 10x faster than competitors",
    "hashtags": ["#startup", "#engineering"],
    "webhook_url": "https://your-app.example.com/webhooks/post"
  }'

Initial response

{
  "success": true,
  "data": {
    "job_id": "pjob_01HKZ...",
    "status": "queued",
    "platforms": [
      { "platform": "tiktok", "status": "queued" },
      { "platform": "instagram", "status": "queued" },
      { "platform": "youtube_shorts", "status": "queued" }
    ]
  },
  "meta": { "request_id": "req_...", "credits_used": 3, "credits_remaining": 997 }
}

Parameters

Completion webhook

{
  "event_type": "post.completed",
  "data": {
    "job_id": "pjob_01HKZ...",
    "status": "partial_success",
    "platforms": [
      {
        "platform": "tiktok",
        "status": "posted",
        "external_id": "7234...",
        "external_url": "https://tiktok.com/@.../video/7234..."
      },
      {
        "platform": "instagram",
        "status": "posted",
        "external_id": "...",
        "external_url": "https://instagram.com/reel/..."
      },
      {
        "platform": "youtube_shorts",
        "status": "failed",
        "error_code": "PLATFORM_OAUTH_EXPIRED",
        "error_message": "YouTube token expired. User must reconnect."
      }
    ]
  }
}

Recurring schedules

For repeat distribution (daily news, weekly digests, content calendars), create a schedule once:

curl -X POST https://api.reelsbuilder.ai/api/v1/schedules \
  -H "Authorization: Bearer $REELSBUILDER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Daily news broadcast",
    "cadence": "daily",
    "time_local": "09:00",
    "timezone": "America/New_York",
    "platforms": ["tiktok", "instagram"],
    "source": {
      "type": "generate_and_post",
      "topic_strategy": "trending_news",
      "brand_id": "brn_01HKZ..."
    }
  }'

Cadence options: daily, weekly, cron (with cron_expression field). Each firing creates one job; webhook fires on completion.

Examples

TypeScript — bulk-post from a library

const auth = { Authorization: `Bearer ${process.env.REELSBUILDER_API_KEY}` };
const videos = [
  { url: "https://cdn.example.com/v1.mp4", caption: "Episode 1: ..." },
  { url: "https://cdn.example.com/v2.mp4", caption: "Episode 2: ..." },
  { url: "https://cdn.example.com/v3.mp4", caption: "Episode 3: ..." },
];

// Post all 3 in parallel; idempotency keys make this safe to retry
await Promise.all(
  videos.map((v, i) =>
    fetch("https://api.reelsbuilder.ai/api/v1/post", {
      method: "POST",
      headers: {
        ...auth,
        "Content-Type": "application/json",
        "Idempotency-Key": `bulk-2026-05-15-${i}`,
      },
      body: JSON.stringify({
        video_url: v.url,
        platforms: ["tiktok", "instagram"],
        caption: v.caption,
        schedule_at: new Date(Date.now() + i * 3600_000).toISOString(),
      }),
    }),
  ),
);

Pricing

• 1 credit per platform per post.
• 3-platform fan-out = 3 credits.
• No charge for video storage (use your own CDN).
• Scheduling itself is free — only the firing costs credits.
• Per-platform failures are not refunded. Each attempt to post counts whether it succeeded or not.

Platform-specific limits

ReelsBuilder validates these on submission and rejects with INPUT_INVALID_FORMAT before charging credits.

OAuth token security

All social tokens are encrypted at rest with AES-256-CBC using user-specific PBKDF2-derived keys (100k iterations, SHA-256). Tokens are never returned over the API — connection status is exposed as a boolean. To rotate or revoke, the end-user must use the dashboard.

See also

• Generate & Post API — generates the video for you
• YouTube Clipper — feeds this endpoint with sliced shorts
• Webhooks — signature verification + retry policy