How to check what technology a website runs on
Short answer
Look in three places: the HTTP response headers (server, x-powered-by, CDN headers), the page source (generator meta tags, script and CSS paths like /wp-content/ or /_next/), and DNS (MX records reveal the email provider, TXT records reveal verified services). An API can read all three and list each technology with the evidence it found.
Copy-paste code
By hand, then with DomainDNA (free tier, no key)
curl -sI https://example.com | grep -iE '^(server|x-powered-by|cf-ray|x-vercel|via):'
curl -s https://example.com | grep -oiE '<meta name="generator"[^>]+>|/wp-content/|/_next/|cdn.shopify.com' | sort -u
dig +short MX example.com
dig +short TXT example.com
# tech stack with evidence, email provider, SPF/DMARC, DNS, domain age
curl "https://domaindna-api.cybermaxtools.com/api/tech?domain=example.com"
curl "https://domaindna-api.cybermaxtools.com/api/report?domain=example.com"Good to know
Detection is evidence-based: a site can hide headers or use a CDN that masks the origin server, so treat a missing signal as "unknown", not "not used".
DomainDNA API: Any website's tech stack and email security, one call
from $5DomainDNA's API returns the tech stack with the evidence for each technology, the email provider, SPF and DMARC policy, DNS, domain age and registrar, security headers and robots/llms/security.txt, read live per call. Free: 25 calls a day.
Secure checkout · 14-day fix-or-refund if it doesn't work as described (terms)Questions
Can I see a site's backend language?
Only when it leaks (headers, file extensions, cookies); many sites don't show it.
Is it legal to check?
Reading public headers, page source and DNS is what every browser does.
Free: the Free API Starter Kit
Copy-paste calls for 4 APIs with free daily tiers (CVE priority, VIN recalls, US duty rates, email checks), then 5 short emails on KEV/EPSS, MCP and free data.