# What is a Slack bot?

> A Slack bot is an app that joins channels, posts messages and replies when someone @mentions it. How bots differ from apps and webhooks, with an ad team example.
- **Author**: Marxx
- **Published**: 2026-11-07
- **Category**: Slack
- **URL**: https://marxx.ai/library-glossary/slack-bot

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A Slack bot is an app that acts like a member of your Slack: you add it to channels, it posts messages, and it replies when someone mentions it with @. Ad tools use bots to post leads and alerts and to answer questions about an ad account in the channel where the team already works.

## App, bot or webhook?

| Term | What it is | Can it reply to you? |
|---|---|---|
| Slack app | The package you install in your workspace. It can include a bot, buttons, forms and webhooks | Depends on what it includes |
| Bot | The part of an app that sits in channels, posts and answers @mentions | Yes |
| Incoming webhook | A simple address an app uses to post messages into one channel | No. It only posts |

Slack's developer docs say an incoming webhook cannot delete a message once posted. A bot can do more, such as update a message after someone presses a button.

Slack's free plan allows up to 10 apps. Paid plans allow unlimited apps (checked 6 Nov 2026, see [Slack pricing](/prices/slack-pricing)).

## Mentions and threads

- **@mention.** Type @ and the bot's name, such as @Marxx, to call it. Many ad tool bots answer only when mentioned.
- **Thread.** The bot answers under your message, not in the main channel. Follow-ups in the thread keep the answer and the conversation together.
- **Slackbot.** Slack's own assistant. Its AI agent comes with Slack AI on paid plans. It is a different thing from the bots that apps add.

## A worked example

Say Northwind Escapes, a made-up client, has a channel `#client-northwind`. An ad tool's bot sits in it.

1. A new lead arrives. The bot posts a message with an **Open lead** button.
2. Priya Shah presses **Mark contacted**. The bot updates the same message: "Contacted by Priya Shah".
3. Karan Mehta types "@Marxx how did our Meta ads do last week?". The bot replies in a thread.

Steps 2 and 3 need a bot. A webhook could post step 1 but could not update it or answer a question. We make Marxx, which works this way, see [Marxx in Slack](/features/slack).

Slack also limits how fast apps post: no more than one message per second per channel, with short bursts allowed.

## FAQ

### Can a Slack bot read every message in a channel?

It depends on the permissions the app asks for. Check them before you install, and ask the vendor what the bot reads.

### Can a bot work in a channel shared with a client?

Some can, some refuse. Ask the vendor whether its bot answers there and who sees the answer. See [Slack Connect](/glossary/slack-connect) for how shared channels work.

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- [More Slack articles](https://marxx.ai/library-glossary/category/slack)
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