Domain Watcher

Domain availability monitor and expiration tracker built with SvelteKit & Cloudflare Workers. Track domains, get Slack/Email alerts, NS and SSL monitoring.

#cloudflare-workers #domain #domain-checker #domain-monitoring #svelte

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Domain Watcher | Domain Availability Monitor & Expiration Tracker

Keywords: domain monitor • domain checker • whois lookup • ssl certificate tracker • domain expiration alerts • sveltekit • cloudflare workers • slack notifications • resend notifications • email notifications

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Monitor domain availability, track expiration dates, and get notifications when domains become available or are about to expire.

A modern domain monitoring tool built with SvelteKit and Cloudflare Workers that tracks domain availability, SSL certificates, and sends smart notifications via Slack or email (Resend).

Perfect for: Domain investors, web developers, businesses tracking competitor domains, and anyone managing domain portfolios.

Tech Stack

Frontend: SvelteKit
Platform: Cloudflare Workers
Database: Cloudflare D1 (SQLite)
Notifications: Slack Webhooks, Resend API
Scheduling: Cloudflare Cron Triggers
Domain API: WhoisJSON (1000 free calls/month)

👀 Overview
🚀 Features
📦 Setup
🛠️ Development
🌐 Deployment
🗃️ Database Schema
🐛 Troubleshooting

👀 Overview

A SvelteKit application running on Cloudflare Workers that monitors domain availability and sends notifications via Slack or Email (Resend) when domains become available.

In addition to available domains, you also receive:

A list of domains that are expiring within 30 days
A list of domains that have already expired but are still registered

A daily summary keeps you informed and helps you act fast.

App Overview

Settings Page

Slack Notification

Email Notification

🚀 Features

Domain Monitoring: Monitor domain status, including availability, nameservers (NS), and SSL certificate validity.
Automated Checks: A cron job runs every minute to evaluate if notification conditions are met (via Slack or Resend), based on the configured time and settings.
Notifications via Slack or Email (Resend): Get notified when domains become available or when specific conditions are met. Choose your preferred notification method (Slack or Email) and configure when alerts should be sent.
Settings Panel: Configure API key for WhoisJSON, choose your preferred view mode for the interface, and manage notification settings for Slack and Resend.
Web Interface: A clean and functional UI where you can add new domains, view and manually refresh domain status, perform bulk checks, and manage your domain list with ease.

📦 Setup

Prerequisites

Node.js and pnpm
Cloudflare Account
WhoIs JSON API key - Get your API key for domain lookups
Slack Webhooks – Create a Slack app and generate an incoming webhook URL for Slack notifications
Resend API – Generate your Resend API key to enable email notifications

🛠️ Development

Local Development Setup

Environment Configuration

Create a local .env file by duplicating the example:

# Copy the example environment file
cp .env.example .env

Then edit .env with your specific values:

PUBLIC_ENVIRONMENT=dev
PUBLIC_TIMEZONE=Europe/Ljubljana
CRON_SECRET=dev-super-secure-key
PRODUCTION_DOMAIN=https://your-app.com

Local Database Setup

Create and configure your local development database:

# Creation of DB and applying schema to local database
npx wrangler d1 execute local-domain-watcher --local --file=./schema.sql

Verify Database Setup

Check that your database was created successfully:

# Verify local database connection
npx wrangler d1 execute local-domain-watcher --local --command="SELECT * FROM domains;"

Expected output: Existing test data

Start Development Server

Launch the local development server:
```
# Start development server
pnpm run dev
```
Your application will be available at: http://localhost:5173

Local Build

Build the application:
```
pnpm run build
```
Start local development server:
```
npx wrangler dev --local
```
Test with cron jobs:
```
npx wrangler dev --test-scheduled
```

Testing Cron Jobs Locally

Manual Trigger

Visit the following URL to manually trigger a cron job:

http://localhost:8787/__scheduled?cron=*+*+*+*+*

Expected Console Output

🚀 Starting cron...
🕐 Check at: 21:23

📝 Note: If you see "✅ Local - Self-call completed successfully!" in the logs, it means the local cron function is running successfully.

Cron Schedule

The cron job runs every minute to check scheduled notifications. Since you can set specific times in Slack or Resend settings (e.g., "Send at 14:30"), the cron job must check every minute to trigger notifications at the exact scheduled time.

Example: If notification is set for 14:30, the cron job checks every minute until it matches 14:30, then sends the notification.

🌐 Deployment - Via Cloudflare with GitHub Integration

Deploy your application using Cloudflare Worker with GitHub integration.

Step 1: Database Setup (Production)

⚠️ Important: Complete database setup before deploying your application!

1.1. Create Production Database

# Connect to CF account and create production database
npx wrangler d1 create prod-domain-watcher

1.2. Update Database Configuration

After creating the database, copy the generated d1_databases configuration into your wrangler.jsonc file under env.production.d1_databases:

"d1_databases": [
    {
      "binding": "DB",
      "database_name": "prod-domain-watcher",
      "database_id": "generated-id"
    }
  ]

1.3. Apply Database Schema

# Apply schema to production database
npx wrangler d1 execute prod-domain-watcher --remote --file=./schema.sql

1.4. Verify Database Setup

# Check if tables were created successfully
npx wrangler d1 execute prod-domain-watcher --remote --command="SELECT * FROM domains;"

Step 2: Create Cloudflare Worker Project:

1. Go to Cloudflare Dashboard:

Navigate to Workers & Pages under Compute (Workers)
Click Create → Workers
Select Connect to Git

2. Import Repository:

Choose your repository (e.g., "domain-watcher")
Enter your project name

Step 3: Build Configuration:

Build command: pnpm run build
Deploy command: npx wrangler deploy --env production

Build variables:

Set these environment variables (update timezone and generate your own secret):

PUBLIC_ENVIRONMENT = production
PUBLIC_TIMEZONE = Europe/Ljubljana         # Change to your timezone (e.g., America/New_York, UTC)
CRON_SECRET = strong-secret-key-here       # Replace with a secure random string (32+ characters)
PRODUCTION_DOMAIN = https://your-app.com   # Set to your live application URL for robots.txt control

⚠️ Important: The CRON_SECRET environment variable must be identical to the value set in your wrangler.jsonc configuration file under env.production.vars.CRON_SECRET!

Step 4: Create & Deploy

Push to Repository: Commit and push your changes to trigger automatic deployment
Monitor Build: Check build logs in Cloudflare Pages dashboard
Verify Deployment: Visit your deployed URL to confirm everything works

Post-Deployment Setup (if needed)

Set Environment Variables in Cloudflare Worker Dashboard:

Go to Settings > Build > Variables and Secrets
Add PUBLIC_ENVIRONMENT, PUBLIC_TIMEZONE, PRODUCTION_DOMAIN and CRON_SECRET

🗃️ Database Schema

The application uses two main tables:

domains Table

Stores domain names and availability status
Tracks domain expiration dates and check history
Stores complete API responses from WhoisJSON (domain, DNS, SSL data)
Includes error logging and check statistics

settings Table

Category-based configuration storage (api, ui, notifications)
JSON-based config data for flexible settings management
Handles API credentials, UI preferences, and notification settings
Supports enabled/disabled states for notification services

For detailed table structure and relationships, see schema.sql

🐛 Troubleshooting

Common Issues

"Database not found": Ensure you've created the database and updated the database_id in wrangler.jsonc
"Environment variables missing": Set PUBLIC_ENVIRONMENT, PUBLIC_TIMEZONE and CRON_SECRET in Cloudflare Dashboard
Cron jobs not working: Ensure CRON_SECRET values are identical in wrangler.toml and Cloudflare Dashboard Variables and Secrets
Cron jobs not working locally: Use npx wrangler dev --test-scheduled and test via the /__scheduled endpoint

Debugging

Check logs in Cloudflare Dashboard under Functions > Logs
Use console.log statements in your code for debugging
Test API endpoints manually using curl or browser developer tools

Check if your database is set up correctly:

### LOCAL ###
# Check database
npx wrangler d1 execute local-domain-watcher --local --command="SELECT * FROM domains";

# Check database structure
npx wrangler d1 execute local-domain-watcher --local --command="PRAGMA table_info(domains);"

# Export database backup
npx wrangler d1 export local-domain-watcher --local --output=backup.sql


### PRODUCTION ###
# Check production database
npx wrangler d1 execute prod-domain-watcher --remote --command="SELECT * FROM domains";

# Check database structure
npx wrangler d1 execute prod-domain-watcher --remote --command="PRAGMA table_info(domains);"

Contributing

Fork the repository
Create a feature branch
Make your changes
Test locally with npx wrangler dev
Submit a pull request

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