How To Create a Slack Bot - Complete Build Tutorial

Slack App Foundations

A Slack app is the container for your bot, commands, and UI. It listens with the Events API and acts with the Web API. Use messages, modals, App Home, and interactive components to create complete workflows. For context on Slack features, see our guides on what Slack is, Slack AI, and omnichannel support.

Create the App and Get Credentials

Register your app, then secure your tokens. You need the Client ID, Client Secret, and Signing Secret for OAuth and request verification.

Initialize a Bolt Project

Use Bolt to handle signatures, OAuth, and event plumbing. Choose Node or Python.

npm init -y


npm install @slack/bolt dotenv

// app.js
require('dotenv').config();
const { App } = require('@slack/bolt');

const app = new App({
token: process.env.SLACK_BOT_TOKEN,
signingSecret: process.env.SLACK_SIGNING_SECRET
});

app.event('app_mention', async ({ event, say }) => {
await say(Hi <@${event.user}>);
});

(async () => {
await app.start(process.env.PORT || 3000);
console.log('⚡️ Bolt app running');
})();

python3 -m venv venv


source venv/bin/activate
pip install slack-bolt python-dotenv

app.py

import os
from dotenv import load_dotenv
from slack_bolt import App

load_dotenv()
app = App(token=os.environ["SLACK_BOT_TOKEN"],
signing_secret=os.environ["SLACK_SIGNING_SECRET"])

@app.event("app_mention")
def handle_mention(event, say):
say(f"Hi <@{event['user']}>")

if name == "main":
app.start(port=int(os.environ.get("PORT", 3000)))

Listen to Events and Add Slash Commands

Subscribe to app_mention and define a command like /echo.

// Node: simple /echo app.command('/echo', async ({ command, ack, say }) => { await ack(); await say(`You said: ${command.text}`); });

# Python: simple /echo @app.command("/echo") def echo(ack, say, command): ack() say(f"You said: {command['text']}")

Create Interactive Messages and Modals

Use Block Kit for buttons and menus. Open modals for structured input.

// Node: open a modal from a command app.command('/survey', async ({ ack, body, client }) => { await ack(); await client.views.open({ trigger_id: body.trigger_id, view: { type: 'modal', callback_id: 'survey_view', title: { type: 'plain_text', text: 'Feedback Survey' }, submit: { type: 'plain_text', text: 'Submit' }, blocks: [ { type: 'input', block_id: 'feedback_block', label: { type: 'plain_text', text: 'Your feedback' }, element: { type: 'plain_text_input', action_id: 'feedback_input', multiline: true } } ] } }); }); app.view('survey_view', async ({ ack, body }) => { await ack(); const user = body.user.id; const feedback = body.view.state.values.feedback_block.feedback_input.value; console.log(`Feedback from ${user}: ${feedback}`); });

Upload and Share Files

Use the modern upload flow or SDK helpers. Request files:write.

# Python SDK helper: files_upload_v2 from slack_sdk import WebClient client = WebClient(token=os.environ["SLACK_BOT_TOKEN"]) client.files_upload_v2( channel="C12345678", file="report.txt", title="Weekly Report", initial_comment="Here is the report" )

Deploy to Production

Choose Heroku for simplicity, AWS Lambda for serverless, or a VPS for full control. Always serve HTTPS.

# Procfile (Node) web: node app.js # Procfile (Python) web: gunicorn app:app

const { App, AwsLambdaReceiver } = require('@slack/bolt'); const receiver = new AwsLambdaReceiver({ signingSecret: process.env.SLACK_SIGNING_SECRET }); const app = new App({ token: process.env.SLACK_BOT_TOKEN, receiver }); module.exports.handler = async (event, context, callback) => { const handler = await receiver.start(); return handler(event, context, callback); };

server { listen 443 ssl; server_name your_domain.com; location / { include proxy_params; proxy_pass http://unix:/home/your_user/mybot.sock; } }