Media Uploads

How to upload images, videos, and documents for use in posts

Posts with media perform better on every platform. Zernio uses presigned URLs for fast, direct uploads up to 5GB.

Upload Flow

1. Request a presigned URL from POST /v1/media/presign
2. Upload the file directly to the returned uploadUrl using a PUT request
3. Use the publicUrl in your post's mediaItems array

Step 1: Get a Presigned URL

const { uploadUrl, publicUrl } = await zernio.media.getMediaPresignedUrl({
  fileName: 'photo.jpg',
  fileType: 'image/jpeg'
});

result = client.media.get_media_presigned_url(
    filename="photo.jpg",
    content_type="image/jpeg"
)
upload_url = result["upload_url"]
public_url = result["public_url"]

curl -X POST "https://zernio.com/api/v1/media/presign" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "fileName": "photo.jpg",
    "fileType": "image/jpeg"
  }'

Response:

{
  "uploadUrl": "https://storage.googleapis.com/...",
  "publicUrl": "https://storage.googleapis.com/...",
  "expires": "2024-01-15T11:00:00.000Z"
}

Step 2: Upload the File

Upload directly to the presigned URL (no auth header needed):

// Upload directly to the presigned URL (no auth needed)
await fetch(uploadUrl, {
  method: 'PUT',
  headers: { 'Content-Type': 'image/jpeg' },
  body: fileBuffer
});

import httpx

# Upload directly to the presigned URL (no auth needed)
with open("photo.jpg", "rb") as f:
    httpx.put(upload_url, content=f.read(), headers={"Content-Type": "image/jpeg"})

curl -X PUT "UPLOAD_URL_FROM_STEP_1" \
  -H "Content-Type: image/jpeg" \
  --data-binary @photo.jpg

Step 3: Use in a Post

Include the publicUrl in your post:

const { post } = await zernio.posts.createPost({
  content: 'Check out this photo!',
  mediaItems: [
    { url: publicUrl, type: 'image' }
  ],
  platforms: [
    { platform: 'twitter', accountId: 'acc_xyz789' }
  ]
});

result = client.posts.create_post(
    content="Check out this photo!",
    media_items=[
        {"url": public_url, "type": "image"}
    ],
    platforms=[
        {"platform": "twitter", "accountId": "acc_xyz789"}
    ]
)

curl -X POST "https://zernio.com/api/v1/posts" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Check out this photo!",
    "mediaItems": [
      { "url": "PUBLIC_URL_FROM_STEP_1", "type": "image" }
    ],
    "platforms": [
      { "platform": "twitter", "accountId": "acc_xyz789" }
    ]
  }'

See the Presigned Upload endpoint for full parameter details.

Supported Formats

Type	Formats	Max Size
Images	JPG, PNG, GIF, WebP	5 GB
Videos	MP4, MOV, AVI, WebM	5 GB
Documents	PDF (LinkedIn only)	100 MB

Platform-Specific Media Rules

Each platform has its own requirements for media. Here's a quick reference:

Platform	Max Images	Max Videos	Notes
Twitter	4	1	No mixing images and videos
Instagram	10 (carousel)	1 (Reel)	Stories: single image/video
Facebook	Multiple	1	Stories: single image/video
LinkedIn	20 images	1	Single PDF supported (max 300 pages)
TikTok	35 photos	1	No mixing photos and videos
YouTube	-	1 (required)	Optional custom thumbnail
Pinterest	1	1	One image or one video per Pin
Bluesky	4	1	Images auto-compressed to ~1MB
Threads	10 images	1	No video carousels
Snapchat	1	1	Required for all post types

For detailed platform requirements, see the Platforms section or the Create Post endpoint.

Auto-Compression

Some platforms have strict file size limits. Zernio handles this automatically:

• Bluesky: Images are automatically recompressed to stay under Bluesky's ~1MB blob limit
• YouTube Thumbnails: Custom thumbnails via MediaItem.thumbnail are processed to meet YouTube's requirements

Custom Media Per Platform

You can use different media for different platforms in the same post using customMedia in the platform entry:

{
  "content": "Same text, different media per platform",
  "mediaItems": [{ "url": "default-image.jpg", "type": "image" }],
  "platforms": [
    { "platform": "twitter", "accountId": "acc_1" },
    {
      "platform": "instagram",
      "accountId": "acc_2",
      "customMedia": [{ "url": "square-image.jpg", "type": "image" }]
    }
  ]
}