How to Tell if a Website Uses Substack
Identifying whether a website was built with Substack used to require technical expertise — inspecting source code, tracing network requests in DevTools, and knowing which patterns to look for. Our free scanner automates all of that: it fetches the page, analyzes 5 Substack-specific signals, and returns a verdict with a confidence score.
You might want to detect Substack for competitive research, due diligence before acquiring a site, or simple curiosity. Whatever the reason, this page covers every method — automated and manual.
What is Substack?
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.
It is primarily used for content-driven websites, blogs, news sites, documentation, and publishing platforms.
Visit Substack official websiteSigns a Website Is Built With Substack
Our detection engine checks 5 unique Substack fingerprints. Here are the most reliable signals:
CDN Domain
Assets (images, scripts, fonts) are loaded from Substack-specific CDN domains. This is one of the most reliable signals because CDN domains are hard to hide.
substackcdn.comJavaScript / Script Files
Substack loads specific JavaScript runtime files or loads scripts from identifiable URLs. Checking script src attributes reveals the platform.
substack.comsubstackcdn.comHTML Attributes & Class Names
Substack injects proprietary class names, data attributes, or markup patterns into the page HTML that are unique to the platform.
substackMeta Tags
Some Substack sites include a generator meta tag or other platform-specific meta elements in the document head.
substackHow to Manually Detect Substack Websites
Method 1 — View Page Source
- Open the website in your browser
- Press
Ctrl+U(Windows) orCmd+Option+U(Mac) - Search (
Ctrl+F) forsubstackorsubstack - If found in script src, class names, or meta tags — it's likely Substack
Method 2 — Browser DevTools Network Tab
- Press
F12to open DevTools - Click the Network tab and reload the page
- Filter by
substackin the search box - If you see requests to Substack-specific domains, it's confirmed
How Our Substack Detector Works
When you submit a URL, our engine fetches the page from its server — just like a browser would — then analyzes the response across 5 Substack-specific fingerprints:
Script analysis
We scan all loaded JavaScript files for known CDN paths and runtime names
CDN domain matching
We cross-reference every asset request against known platform CDNs
HTML pattern scanning
We search the DOM for platform-specific class names and data attributes
Header inspection
We read HTTP response headers that identify the server or platform
Meta tag extraction
We check generator and other meta tags in the document head
Confidence scoring
We weight each matched signal and normalize to a 0–99% score
How to Build a Similar Website With Substack
Install Substack from https://substack.com, set up your content models, and connect a frontend framework like Next.js or Gatsby to display your content.
Other popular CMS platforms include WordPress, Ghost, Contentful, Sanity, and Strapi.
Get started with SubstackFrequently Asked Questions
How can I tell if a website was built with Substack?
The most reliable ways to detect Substack are: (1) open DevTools → Network tab and look for requests to Substack-specific CDN domains, (2) view page source and search for Substack-specific class names or data attributes, (3) use our free scanner — we check 5 detection signals automatically and return a confidence score.
Is your Substack detector free?
Yes, completely free. Paste any URL into our scanner and we'll analyze it for Substack fingerprints immediately. No account required, no limits on scans.
How accurate is the Substack detection?
We check 5 unique Substack fingerprint signals across HTML, JavaScript, CDN domains, meta tags, and HTTP headers. Our confidence score reflects how many signals matched — a score above 70% is a strong indicator. We cap accuracy at 99% to reflect that all fingerprint-based detection is probabilistic.
Can Substack sites be detected if they use a custom domain?
Yes. Custom domains don't hide the underlying platform. The JavaScript files, CDN requests, HTML attributes, and server headers all remain identifiable regardless of the domain name used. Our scanner fetches the page directly and analyzes its technical composition.
What should I do after detecting a Substack website?
If you want to build something similar, visit https://substack.com to learn more or sign up. If you're doing competitive research, our scan result also shows the full technology stack — including hosting platform, domain age, and other detected technologies. You can share the result link with your team.