Upload media

Returns a presigned URL you can PUTa file to, plus the public URL of the resulting object. Use this when you don't want to host the media yourself, or when you need the file to stay reachable for scheduled posts where the window between the API call and the actual publish can span hours or days.

You don't have to use this endpoint. If you already host your media somewhere publicly accessible, you can pass that URL straight into the media array on POST /v1/posts— Synposter will fetch it for you. This endpoint exists for the case where hosting your own media isn't convenient.

How it works

1. Call POST /v1/media with the filename and MIME type. We respond with an upload_url (a short-lived presigned URL), a public_url (where the file will live), and an expires_at timestamp.
2. PUT the raw file bytes to upload_url, with the same Content-Type you declared in step 1. No auth header needed — the URL itself is the authorization.
3. Reference public_url in any subsequent POST /v1/posts call: media: [{ type: "image", url: public_url }].

Body

Response (201)

{
  "id": "9b3a1f2c-...",
  "upload_url": "https://<project>.supabase.co/storage/v1/object/upload/sign/media/...",
  "public_url": "https://<project>.supabase.co/storage/v1/object/public/media/<prefix>/<uuid>.png",
  "path": "<prefix>/<uuid>.png",
  "mime_type": "image/png",
  "expires_at": "2026-04-29T16:00:00Z"
}

Example: full upload + post

# 1. Get a presigned URL.
RESP=$(curl -s -X POST https://api.synposter.com/v1/media \
  -H "x-api-key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "filename": "cat.png", "mime_type": "image/png" }')

UPLOAD_URL=$(echo "$RESP" | jq -r .upload_url)
PUBLIC_URL=$(echo "$RESP" | jq -r .public_url)

# 2. PUT the file to the presigned URL.
curl -X PUT "$UPLOAD_URL" \
  -H "Content-Type: image/png" \
  --data-binary @./cat.png

# 3. Reference the public URL in a post.
curl -X POST https://api.synposter.com/v1/posts \
  -H "x-api-key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d "{
    \"accounts\": [\"<account_id>\"],
    \"text\": \"Hello with image!\",
    \"media\": [{ \"type\": \"image\", \"url\": \"$PUBLIC_URL\" }]
  }"

Limits

• Max file size: 50MB per object. The upload itself is rejected at the storage layer if you exceed this — your PUT returns an error and nothing is stored.
• Allowed MIME types: anything starting with image/ or video/. Other types (PDFs, audio, etc.) are rejected with invalid_mime_type.
• URL TTL: upload_url is valid for 2 hours from issuance. The public_url never expires (the file stays available as long as the object exists).
• Per-platform constraints still apply when you reference the URL in POST /v1/posts — for example, X enforces a 5MB cap on images and a 15MB cap on GIFs even though the upload itself succeeded at the larger bucket limit.