Slack character counter

Slack limits at a glance

• Text: up to 40,000 characters.
• Media: up to 10 files per post.
• Follow-ups: yes. Postozo posts follow-up comments or thread items after the main post.
• Settings in Postozo: none needed.

How Slack counts characters

Postozo allows up to 40,000 characters for a Slack message. In practice, short messages are read more. Slack formatting symbols count as characters.

Among the 23 networks with a counter here, Slack has the 13th shortest of 14 different limits. Reddit and Tumblr have the same limit of 40,000. Shorter is not worse: it only changes how you write. A long limit means the first lines matter most, because that is what people see before they open the post.

This counter counts each character (Unicode code point), the same way Postozo checks it before saving.

Rules Postozo checks for Slack

Slack markdown (mrkdwn). Files are uploaded to the channel. Follow-up comments become replies in the thread.

How to use this Slack counter

1. Write or paste your Slack message in the box above.
2. Watch the "left" number. It turns amber when less than 10% is left and red when the text is too long.
3. Count links and hashtags as part of the text: Slack counts them too.
4. Too long? Move the rest to a follow-up. Postozo posts follow-ups right after the main post.

Connecting Slack to Postozo

You connect Slack by pasting your details, which Postozo stores encrypted:

• Bot token: Create a Slack app with chat:write and files:write, install it, and copy the Bot User OAuth Token.
• Channel ID: In Slack, open the channel details. The ID is at the bottom.

Slack does not share statistics with Postozo, so you see the publish status and the live link for each post.

Tips for Slack posts

• Slack uses its own markdown (mrkdwn): *bold* and _italic_.
• Follow-up comments become replies in the thread, which keeps the channel tidy.
• Files are uploaded to the channel with the message.
• Invite the app to the channel first (/invite @your-app).

Before you post on Slack

• Read the post on a phone screen. Most people will see it there, and long lines look longer on a small screen.
• Open every link once to check it works and goes to the right page.
• Keep the full, longer version of your text. You may want it for a network with more room than Slack.

Write once, fit every network

If you post the same message to several networks, Postozo lets you write it once and change the text for Slack only. The AI assistant can shorten a post to fit Slack, and the post editor warns you before a post breaks a rule. See every network's limit on the all-networks character counter.