Claude Code — Slack Notification Hook

Sends a Slack message when Claude Code finishes a task (Stop event), using incoming webhooks.

Why / When to Use

Use when you want a real-time Slack ping every time Claude Code completes a turn — useful for long-running autonomous sessions where you’re not watching the terminal.

Core Concept / Commands

Step 1 — Create Slack Incoming Webhook

Go to api.slack.com/apps → Create New App → From scratch
Add Incoming Webhooks, enable it → Add New Webhook to Workspace
Pick a channel → copy the webhook URL: https://hooks.slack.com/services/...

Step 2 — Create hook script

mkdir -p ~/.claude/hooks
nano ~/.claude/hooks/notify-slack.sh

#!/bin/bash
# ~/.claude/hooks/notify-slack.sh
 
SLACK_WEBHOOK_URL="${SLACK_WEBHOOK_URL}"
 
if [ -z "$SLACK_WEBHOOK_URL" ]; then
  exit 0
fi
 
input=$(cat)
session_id=$(echo "$input" | jq -r '.session_id // "unknown"')
project=$(echo "$input" | jq -r '.cwd // "unknown"' | xargs basename)
 
curl -s -X POST "$SLACK_WEBHOOK_URL" \
  -H 'Content-type: application/json' \
  --data "{\"text\": \"✅ Claude Code done — project: \`${project}\` (session: \`${session_id}\`)\"}"

chmod +x ~/.claude/hooks/notify-slack.sh

Step 3 — Set webhook URL in environment

# Add to ~/.zshrc or ~/.bashrc
export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/YOUR/WEBHOOK/URL"

Step 4 — Register in Claude Code settings

Edit ~/.claude/settings.json (global) or .claude/settings.local.json (per-project):

{
  "hooks": {
    "Stop": [
      {
        "matcher": "*",
        "hooks": [
          {
            "type": "command",
            "command": "~/.claude/hooks/notify-slack.sh"
          }
        ]
      }
    ]
  }
}

Key Options / Variants

Notification hook (fires when Claude needs input): add same pattern under "Notification" key with a "⚠️ Claude needs attention" message
Per-project scope: put in .claude/settings.local.json inside the project folder
Global scope: ~/.claude/settings.json

The hook reads JSON from stdin (including session_id, cwd, etc.) and posts to Slack via curl.

Gotchas

The SLACK_WEBHOOK_URL env var must be set in the shell that launches Claude Code
Script reads stdin — don’t forget input=$(cat) before parsing
Uses jq — ensure it’s installed (brew install jq / apt install jq)

Source

Conversation: “Integrating Claude with Slack notifications” — 2026-05-18

PKM

Claude Code — Slack Notification Hook (Stop)