Images

The subscribe page shows a logo next to the name and a banner at the top. You upload both as a raw image, meaning the image itself is the request body, not JSON or a form.

PUT    /v1/publisher/calendars/{calendar_id}/images/logo
PUT    /v1/publisher/calendars/{calendar_id}/images/banner
DELETE /v1/publisher/calendars/{calendar_id}/images/logo
DELETE /v1/publisher/calendars/{calendar_id}/images/banner

Upload

curl -X PUT https://api.kalender-sync.de/v1/publisher/calendars/$KS_CAL/images/logo \
  -H "Authorization: Bearer $KS_KEY" \
  -H "Content-Type: image/png" \
  --data-binary @logo.png

--data-binary matters, so curl sends the image unchanged. The response is 200 OK with the full calendar, including the new logo_url or banner_url. A new image replaces the old one.

	Logo	Banner
Formats	PNG, JPEG, WebP	PNG, JPEG, WebP
Size	up to 512 KB	up to 2 MB
Recommended	square, at least 192 × 192 px	about 3:1, at least 1200 px wide

• Content-Type: image/png, image/jpeg, image/webp or application/octet-stream. We check whether it really is PNG, JPEG or WebP by the file’s content, not by the header.
• No SVG. SVG can carry scripts and is refused.
• Aspect ratios and minimum sizes are recommendations for a good look. The API only checks format and file size.

Remove

curl -X DELETE https://api.kalender-sync.de/v1/publisher/calendars/$KS_CAL/images/banner \
  -H "Authorization: Bearer $KS_KEY"

Response 204 No Content.

Image URLs

logo_url and banner_url point to our own domain, for example

https://app.kalender-sync.de/api/public/subscribe/cal_XXXXXXXXXXXX/images/logo?v=…

The v parameter changes with every new image. Browsers can cache the images for a long time and still show the new one after an upload. Visitors of the subscribe page load nothing from third-party servers.

Errors

Code	Status	When
invalid_image	400	Empty body
image_too_large	413	Logo over 512 KB, banner over 2 MB
unsupported_image_type	415	Content is not PNG, JPEG or WebP (e.g. SVG, GIF)
unsupported_media_type	415	The Content-Type is not accepted
payload_too_large	413	Body well over 2 MB