How to Auto-Post YouTube Shorts via API

What YouTube actually requires for a Short

A YouTube Short is a regular video that meets two conditions:

1. Aspect ratio 9:16 (vertical)
2. Duration ≤ 60 seconds

YouTube auto-detects Shorts from these properties — there is no separate Shorts endpoint. It’s videos.insert with a 9:16 ≤60s file. The hard parts are OAuth refresh, the resumable upload protocol, and getting Google to approve your project for production use (without that, refresh tokens silently expire after seven days).

With Postproxy

curl -X POST "https://api.postproxy.dev/api/posts" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "post": {
      "body": "60 seconds on the new release.\n\n#Shorts"
    },
    "profiles": ["youtube"],
    "media": ["https://yourcdn.com/short-1080x1920.mp4"],
    "platforms": {
      "youtube": {
        "title": "How we cut publishing latency in half",
        "privacy_status": "public"
      }
    }
  }'

Postproxy runs against a verified YouTube project and handles OAuth refresh, the resumable upload, and the Shorts metadata. You hand over an MP4 and a title; the rest is on us.

YouTube platform parameters

The post body becomes the YouTube description (max 5,000 chars).

curl -X POST "https://api.postproxy.dev/api/posts" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "post": {
      "body": "Why we cut our publishing latency in half.\n\nFull writeup: postproxy.dev/blog\n\n#Shorts #BuildInPublic"
    },
    "profiles": ["youtube"],
    "media": ["https://yourcdn.com/latency-cut.mp4"],
    "platforms": {
      "youtube": {
        "title": "How we cut publishing latency in half",
        "privacy_status": "public",
        "tags": ["shorts", "buildinpublic", "saas"],
        "category_id": "28",
        "made_for_kids": false,
        "contains_synthetic_media": false
      }
    }
  }'

Common category IDs: 22 (People & Blogs), 27 (Education), 28 (Science & Technology), 26 (How-to & Style), 24 (Entertainment), 10 (Music).

Scheduled publish

YouTube’s API doesn’t accept a future timestamp on a public upload — only on a private upload via status.publishAt. Pass scheduled_at to Postproxy and it holds the post (uploads at the scheduled time):

curl -X POST "https://api.postproxy.dev/api/posts" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "post": {
      "body": "Tutorial drop: AI agents that can publish.",
      "scheduled_at": "2026-05-20T15:00:00Z"
    },
    "profiles": ["youtube"],
    "media": ["https://yourcdn.com/agents-tutorial.mp4"],
    "platforms": {
      "youtube": {
        "title": "AI agents that publish",
        "privacy_status": "public"
      }
    }
  }'

Custom thumbnail

{
  "platforms": {
    "youtube": {
      "title": "How to ship faster",
      "privacy_status": "public",
      "cover_url": "https://yourcdn.com/thumbnail-1280x720.jpg"
    }
  }
}

cover_url requires a verified YouTube account (phone-verified). Without verification, YouTube auto-generates the thumbnail from a frame.

Bulk auto-posting from a content folder

A common pattern: an editorial team produces 3 Shorts a week. The team uploads finished MP4s to a shared folder; a worker picks them up and queues them.

pip install postproxy-sdk

import asyncio
import glob
import os
from postproxy import PostProxy, PlatformParams, YouTubeParams

QUEUE_ID = "q_yt_shorts"

async def main():
    async with PostProxy(os.environ["POSTPROXY_API_KEY"], profile_group_id="pg-abc") as client:
        for path in sorted(glob.glob("/content/shorts/*.mp4")):
            cdn_url = upload_to_cdn(path)
            title = os.path.basename(path).replace(".mp4", "").replace("-", " ").title()

            await client.posts.create(
                f"{title}\n\n#Shorts",
                profiles=["youtube"],
                media=[cdn_url],
                queue_id=QUEUE_ID,
                platforms=PlatformParams(
                    youtube=YouTubeParams(
                        title=title,
                        privacy_status="public",
                    ),
                ),
            )
            os.rename(path, path + ".queued")

asyncio.run(main())

The queue assigns each Short to the next slot. See Schedule TikTok posts for the queue creation example, or the Queues API docs.

Common failure modes

DIY vs delegate

DIY makes sense if you publish 1-2 videos a week and have an in-house engineer who can babysit the pipeline. Delegate when you cross any of: 5+ videos/week, multi-channel, multi-brand, or “the marketer needs to be unblocked when an engineer is on vacation.” For the deeper guide, see YouTube upload API guide and YouTube API posting integration.