Post to Slack from your Mac and iPhone
Post to Slack as yourself or as the PostOnly bot, or through a plain webhook.
Live Free for your first account
What PostOnly enforces for Slack
| Character limit | No limit |
|---|---|
| Images per post | 10 |
| Auto-threading | No |
| Title field | No |
| Image required | No |
Image rules
- Bot connection: up to 10 images per post, each under 10 MB
- Incoming webhook: text only, no images
Posting to Slack with PostOnly
Slack has two ways in. The sign-in connection posts text and images, either as you (your own name and picture) or as the PostOnly bot. An Incoming Webhook is simpler but posts text only.
Neither has a character cap worth warning about, so PostOnly sets no limit.
How to connect Slack
- Sign-in: choose Add Account → Slack, click Sign in with Slack, approve PostOnly, then choose the channel and whether to post as yourself or as the bot.
- Webhook: create an app at api.slack.com/apps (from scratch, no review needed). Under Incoming Webhooks, activate it and add a webhook to your workspace for the channel you want, then copy the URL.
- In PostOnly choose Add Account → Slack Webhook, give it a label you will recognize, and paste the URL.
Good to know
- The bot only lists channels it can see. Invite it to a private channel first.
- Bot access does not expire on its own. Reconnect only if Slack revokes it.
- Slack does not share channel names with webhook apps, so the label you type is how you recognize it in PostOnly.
- The webhook URL is a secret and is stored in your Keychain.