Summarize YouTube video transcripts in Discord with Gemini and Supabase

YouTube Video Transcript Summarizer — Discord Bot

> Paste a YouTube URL into a Discord channel and this workflow automatically extracts the transcript, uses an LLM to generate a concise summary, and stores everything in a database — all in seconds.

> Self-hosted n8n only. This workflow uses the Execute Command node to run yt-dlp inside the n8n container. This requires shell access, which is only available on self-hosted instances (Docker, VPS, etc.) — it will not work on n8n Cloud.

Import this workflow into n8n

Prerequisites

| Tool | Purpose | |------|---------| | Discord Bot | Listens for messages and sends replies | | yt-dlp | Downloads subtitles and video metadata (must be installed in the n8n container) | | Google Gemini API | Summarizes video transcripts (Gemini 2.5 Flash) | | Supabase | Stores video data and run logs |

Credentials

| Node | Credential Type | Notes | |------|----------------|-------| | Discord Trigger | Discord Bot Trigger | Bot token with Message Content Intent enabled | | Discord Reply / Discord Not YouTube Reply / Discord Error Reply | Discord Bot | Same bot, used for sending messages | | Message a model (Gemini) | Google Gemini (PaLM) API | API key from Google AI Studio | | Save to Supabase / Log Run / Log Run Error | Supabase | Project URL + anon key |

What It Does

When a user pastes a YouTube URL into a Discord channel, the workflow:

Detects the YouTube URL using RegEx (supports youtube.com, youtu.be, shorts, live) Extracts the video's subtitles (English and Vietnamese) and metadata using yt-dlp Cleans the raw VTT subtitle file into plain-text transcript Summarizes the transcript using an LLM (Gemini 2.5 Flash) into a TLDR + detailed summary (in the original language) Stores the video metadata, full transcript, and AI summary in a Supabase database Logs every run (success or error) to a separate runs table for tracking Chunks long summaries into Discord-safe messages (≤2000 characters each) Replies in Discord with the video title, stats, and the full summary

Non-YouTube messages get a friendly "not a YouTube link" reply. Errors are caught, classified, logged to the database, and reported back to Discord.

How It Works

Main Flow (Happy Path)

Discord Trigger → Extract YouTube URL → Is YouTube URL? ├─ Yes → yt-dlp Get Metadata → Parse Metadata → Read Subtitle File → Parse Transcript │ → Message a model (Gemini) → Prepare Insert Data → Save to Supabase │ → Prepare Success Log → Log Run → Prepare Messages for Discord → Discord Reply └─ No → Discord Not YouTube Reply

Error Flow

Error Trigger → Prepare Error Data → Log Run Error → Discord Error Reply

Node Breakdown

| # | Node | Type | Description | |---|------|------|-------------| | 1 | Discord Trigger | Discord Bot Trigger | Fires on every message in the configured channel | | 2 | Extract YouTube URL | Code | RegEx extracts video ID from message content | | 3 | Is YouTube URL? | IF | Routes YouTube URLs to processing, others to rejection reply | | 4 | yt-dlp Get Metadata | Execute Command | Downloads subtitles (.vtt, English/Vietnamese) and prints metadata JSON | | 5 | Parse Metadata | Code | Extracts title, channel, views, duration via RegEx; decodes Unicode for multi-language support | | 6 | Read Subtitle File | Execute Command | Dynamically finds and reads the .vtt file (continueOnFail enabled) | | 7 | Parse Transcript | Code | Strips VTT timestamps/tags, deduplicates lines | | 8 | Message a model | Google Gemini | Sends transcript to Gemini 2.5 Flash for TLDR + detailed summary (in original language) | | 9 | Prepare Insert Data | Code | Merges summary with all metadata fields | | 10 | Save to Supabase | Supabase | Inserts full record into videos table | | 11 | Prepare Success Log | Code | Builds success run record | | 12 | Log Run | Supabase | Inserts into runs table | | 13 | Prepare Messages for Discord | Code | Chunks long summaries into Discord-safe messages (≤2000 chars) | | 14 | Discord Reply | Discord | Posts summary preview to channel | | 15 | Discord Not YouTube Reply | Discord | Replies when message isn't a YouTube link | | 16 | Error Trigger | Error Trigger | Catches any unhandled node failure | | 17 | Prepare Error Data | Code | Classifies error type and extracts context | | 18 | Log Run Error | Supabase | Logs error to runs table | | 19 | Discord Error Reply | Discord | Posts error message to channel |

Setup Guide

1. Discord Bot

Go to the Discord Developer Portal Create a new Application → Bot Enable Message Content Intent under Privileged Intents Copy the Bot Token Invite the bot to your server with Send Messages + Read Messages permissions In n8n, create a Discord Bot Trigger credential (for listening) and a Discord Bot credential (for sending replies) Update the guild ID and channel ID in the Discord Trigger node and all Discord reply nodes

2. yt-dlp

yt-dlp must be installed in your n8n container. For Docker-based installs:

docker exec -it n8n apk add --no-cache python3 py3-pip docker exec -it n8n pip3 install yt-dlp

Optional: Place a cookies.txt file at /home/node/.n8n/cookies.txt to avoid age-gated or bot-detection issues.

3. Google Gemini API

Go to Google AI Studio Click Create API Key and copy it In n8n, click the Gemini node → Credential → Create New Paste your API key and save

4. Supabase

Create a project at supabase.com Go to Settings → API and copy the URL and anon key In n8n, create a Supabase credential with your URL and API key Run the SQL below in the Supabase SQL Editor to create the required tables

Supabase SQL

-- Videos table: stores video metadata, transcript, and AI summary CREATE TABLE videos ( video_id TEXT PRIMARY KEY, title TEXT, channel TEXT, upload_date TEXT, duration INT, view_count INT, description TEXT, transcript TEXT, ai_summary TEXT, thumbnail_url TEXT, channel_id TEXT, date_added TIMESTAMPTZ DEFAULT now() );

-- Runs table: logs every workflow execution (success or error) CREATE TABLE runs ( video_id TEXT PRIMARY KEY, process_status TEXT NOT NULL, error_type TEXT, notes TEXT, date_added TIMESTAMPTZ DEFAULT now() );