Substack is a newsletter-focused content management and publishing platform used primarily by independent writers, journalists, and media creators who monetize their content through paid subscriptions. The platform has a distinct technical footprint that makes it reliably identifiable: our detection engine recognizes Substack-powered sites through a combination of 2 script patterns, 1 CDN domain, 1 HTML pattern, and 1 meta tag pattern embedded in the page source. These signals — including characteristic script references tied to Substack's CDN infrastructure and specific HTML markup and meta tag conventions consistent across all Substack publications — allow for high-confidence identification regardless of whether a site uses a custom domain. Substack operates as a fully hosted platform, meaning publishers do not manage their own server infrastructure, which keeps the technical signature highly consistent and predictable across deployments. This uniformity makes Substack one of the more straightforward CMS platforms to detect accurately, as its front-end delivery relies on centralized assets that appear on every publication regardless of custom branding or domain configuration.
Detect Substack Websites — Free Tool
Enter any URL to check if it was built with Substack. Instant results, no account required.
How we detect Substack — see our methodology: AI Influence Score calculation, evidence tiers, and fingerprint signal types.
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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