Slack
Slack character limit and media specs
| Message length | 40,000 characters (truncates around 4,000 in the UI) |
| Text formatting | mrkdwn — *bold*, _italic_, `code` |
| Attachments | 20 blocks per message |
Platform limits change — verify against the official docs before betting a campaign on one.
Good to know
Slack collapses messages over ~4,000 characters behind a "Show more" — keep announcements under that.
/ — over by
SawirPost's composer counts against each network's limit as you type — and when a draft runs over on Slack, it can split into a thread at word boundaries instead of getting cut off.