Platform limits: captions, titles, covers, video

Nine platforms, nine sets of limits. The composer enforces these as you type, so you find out before a post is scheduled rather than after it fails. The numbers below are read straight from the same configuration the publisher uses.

Caption and title limits

Titles exist on YouTube and Pinterest only. On the rest, the caption is the whole post. In a CSV import, the title column feeds exactly those two.

Video, everywhere

These apply on every platform, not per platform. Anything over them is stopped before it enters the queue rather than failing at publish time. Video uploads run in the background over a resumable connection, so a large file does not lock the composer.

Individual platforms may be stricter about what they accept for a given post type — a Reel and a long-form upload are not the same thing to Instagram. If a platform rejects a file it took here, the reason lands on the post; see why a post failed.

Post types, covers and alt text

Reading the cover column

• Upload one — attach your own image as the cover or thumbnail.
• Pick a frame — scrub the video and choose the frame to freeze on.
• Set by the platform — X, Threads and Bluesky generate the still themselves, and their APIs accept no alternative.

Pinterest video pins require a cover, so one is always set. Everywhere else it is optional and falls back to the platform default.

Images

Instagram is the one platform with an aspect-ratio rule enforced before publish: images must sit between 0.8 and 1.91 — roughly 4:5 portrait through 1.91:1 landscape. Anything outside that is rejected by Instagram, so it is caught here first.

Alt text is offered on LinkedIn, Pinterest and Bluesky, which are the platforms whose APIs accept it on a scheduled post.

What each platform can do beyond the numbers — the settings, the extras, the connection details — is on its own page: Instagram, Facebook, TikTok, YouTube, LinkedIn, X, Pinterest, Threads, Bluesky.