How the composer works
You start with one main draft: the text, images or video you want to share. Pick the channels it should go to and the composer shows a live preview for each one, side by side, so you can see the Instagram crop, the Threads line breaks and the YouTube description before anything goes out.
When one network needs something different, open its tab and change it there. A shorter line for Bluesky, extra hashtags for Instagram, a title for YouTube. Those edits stay with that network. If you go back and change the main draft, your tailored versions are kept, so you never lose work by fixing a typo.
Drafts save on their own as you type. Close the tab halfway through a sentence and it is still there when you come back.
Threads, first comments and saved sets
Some posts are more than one message. Add follow-ups and Tesselith publishes them as a thread on X, Bluesky, Threads and Mastodon, or as the first comment on LinkedIn and Instagram, which is where people usually put links and hashtags.
If you post to the same group of channels often, save them as a set. A set remembers the channels and can add a line of text before or after every post, such as a sign-off or a campaign hashtag, so you don't type it each time.
Problems caught while you write
Every network has its own rules for length, image size, video length and aspect ratio. The composer checks each one as you type and tells you which network has a problem and what to change. You find out at your desk, not from a failed post at 9am.