Substack is the largest and most influential newsletter and subscription platform, hosting hundreds of the world's top writers, journalists, and independent media outlets — including publications that have generated millions in annual subscriber revenue. It pioneered the paid newsletter model with simple 10% revenue sharing, a writer-friendly setup experience, and a built-in discovery network. Substack Recommendations has become a major growth channel, with reader suggestions driving new subscriber acquisition. Substack sites are identifiable through resources loaded from substackcdn.com for media and assets, the Substack JavaScript runtime on all publication pages, and distinctive *.substack.com subdomain patterns. Custom domain sites still load all media through substackcdn.com, making it a reliable detection signal. The platform is free to use with Substack taking 10% of paid subscription revenue.
Detect Substack Websites — Free Tool
Enter any URL to check if it was built with Substack. Instant results, no account required.
How to Detect Substack Websites
Script Patterns
2 patterns
CDN Domains
1 patterns
HTML Patterns
1 patterns
Meta Tags
1 patterns
1. Check the Page Source
Open the website in your browser, right-click, and select "View Page Source". Search for substack-specific patterns in the HTML.
2. Look for Script Files
Check the Network tab in DevTools for JavaScript files loaded from Substack domains.
3. Check CDN Domains
Network requests to these CDN domains indicate a Substack site:
substackcdn\.com4. Use AI Website Detector (Easiest)
Our automated scanner checks all these signals at once and gives you an instant confidence score. Just enter any URL above.
Frequently Asked Questions
Is this website built with Substack?
You can detect if any website was built with Substack by using our free scanner above. Just enter the URL and we'll analyze HTML patterns, JavaScript files, CDN domains, and HTTP headers to determine if Substack was used — with a confidence score.
How to detect if a website was built with Substack?
There are several ways to detect Substack: (1) View the page source and look for Substack-specific class names or script URLs, (2) Check the Network tab in DevTools for requests to Substack CDN domains, (3) Use our free tool — we check 4 detection signals automatically.
What websites are built with Substack?
Substack is used by thousands of websites worldwide. Our scanner has detected many Substack-built sites across different industries. You can scan any URL to check if it uses Substack.
How accurate is the Substack detection?
Our Substack detection engine checks 4 unique fingerprint signals, achieving high confidence results. We score each match and return a confidence percentage so you know how certain the detection is.
About Substack
Substack is a leading cms used by thousands of businesses and developers worldwide. Our detection engine can identify Substack-built websites with high confidence by analyzing multiple technical signals.
Whether you're a developer doing competitive research, a designer looking for inspiration, or just curious about how a website was built — AI Website Detector gives you instant, accurate detection.
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Detection Info
- Category
- CMS
- Signals Used
- 4 patterns
- Accuracy
- High
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