Free Tech Stack Checker
Paste a URL. See hosting, frameworks, analytics, payments, auth, DNS and more. Free scan on any site, full stack plus API on paid plans. Built for the same company graph as our directory.
Tool briefWhat this tool offersPaste a URL to see the hosting, frameworks, analytics, payments, auth and DNS behind any site linked to the company that runs it.
What it does
- Detects CDN, hosting, frameworks, CMS, analytics, payments, auth and support tooling from the public site.
- Reads DNS nameservers, TLS and mail authentication records (SPF, DKIM, DMARC).
- Domain-verification TXT records reveal SaaS vendors that never appear in the page HTML.
- Attaches the company behind the domain, with funding and founders, from the StartupHub.ai directory.
Why it is different
- The checker uses 395 detector signatures across 26 groups.
- Results are joined to a graph of 25,000+ company profiles.
- Example: notion.com, captured 27 August 2026, showed Cloudflare CDN, Vercel hosting, Next.js and Tailwind, Cloudflare DNS, SPF, DMARC p=reject and TLS 1.3.
- Priced per scan in credits rather than per seat, and StartupHub Monitor can alert when a company adds or drops a technology.
How to use it
- Enter a domain such as example.com.
- Run the scan.
- Read the first three detected technologies, free.
- For the full stack, use a paid plan or the API.
You provide: A domain or URL.
You get: A grouped list of detected technologies and the linked company profile, with three technologies on the free result and the full stack as JSON via the API.
Limits, API and MCP details are in the full brief: /tech-stack.md
Use cases
What people use a website technology lookup for
Knowing a prospect runs Stripe, Segment and Intercom tells you what to lead with, and knowing they run your competitor tells you the deal is a rip-and-replace before you write the first email. Filter our directory by technology to build the list, then scan the domains you add from anywhere else.
Stack changes are strategy made visible. A move off a legacy CMS, a new payment processor, a first observability vendor: each one is a decision that was taken weeks before any announcement. Put a Monitor on the domains you care about and read the change the day it ships.
Before an investment or an acquisition, the stack is evidence. TLS version and mail authentication show operational hygiene, the hosting and CDN show where the money goes, and the absence of an observability or error-tracking vendor tells you something the deck will not.
If you are building an integration, the fastest qualification is whether the target already runs the platform you plug into. Scan the domain, read the auth and payments groups, and you know in a second whether the integration is worth building for them.
Everything on this page is available as a REST call and over MCP, so an AI agent can look a domain up mid-task. It is one credit per domain, or pay per call with x402 and no account at all.
Knowing a prospect runs Stripe, Segment and Intercom tells you what to lead with, and knowing they run your competitor tells you the deal is a rip-and-replace before you write the first email. Filter our directory by technology to build the list, then scan the domains you add from anywhere else.
- UdioStripe, RecurlyIntercomVercel
- KalshiStripeIntercomVercel
- Hero HealthStripeIntercom, Zendesk-
- BrelliumStripeHubSpot, IntercomVercel
- FinofoStripeIntercom-
- Magic HourStripeIntercomGCP
Your target list
- Payments: Stripe
- Support: Intercom
- Source: live site scans
How we compare
BuiltWith and Wappalyzer tell you the tech. We tell you the tech and the company, funding, founders, profile: at a fraction of the price, with an API built for AI agents.
| Capability | StartupHub | BuiltWith | Wappalyzer |
|---|---|---|---|
| Free instant web check | Yes | Partial | Yes |
| Pay-per-scan / credit pricing (no seat lock-in) | Yes | No | Partial |
| Cheapest per-lookup on the market | Yes | No | No |
| Company context: funding, founders, profile | Yes | No | No |
| Filter companies by the tech they use | Yes | Yes | Yes |
| DNS, TLS and mail-auth records, not just page scripts | Yes | Partial | No |
| REST API + MCP for AI agents | Yes | Partial | Partial |
| Monitor & alert on tech-stack changes | Yes | Partial | No |
| Pay-per-call with crypto (x402, no account) | Yes | No | No |
full partial / paid add-on not offered. Comparison reflects publicly documented capabilities and is updated periodically.
What we detect
Tech stack checker FAQ
What is a tech stack checker?
A tech stack checker takes a domain and reports the technologies that site runs: its CDN and hosting, frontend framework, CMS, analytics, payment processor, authentication provider, support tooling and more. Ours reads the public surface of the site plus its DNS, TLS and mail records, then attaches the company behind the domain, so you get the stack and the business context in one result.
How is this cheaper than BuiltWith?
BuiltWith sells seat-based subscriptions that run into the hundreds per month. We charge per scan in credits, so you only pay for the lookups you actually run, and stored results from our directory are effectively free to read.
Where does the data come from?
We detect technologies from a site’s public surface using 395 signatures across 26 groups, then enrich the result with the company context in our graph of 25,000+ company profiles (funding, founders, profile). Results you scan are cached, so repeat reads are instant.
What can DNS and mail records tell you?
Plenty that a page scan alone cannot. Domain-verification TXT records are left behind by the SaaS tools a company has connected, so they surface vendors that never appear in the page HTML: helpdesks, recruiting platforms, e-signature, payroll, security tooling. Nameservers name the DNS provider, the MX host names the mail provider, and SPF, DKIM and DMARC show how seriously the domain is defended against spoofing.
Can I scan a whole list?
Yes. The API takes a domain per call (1 credit each) and is built for batch use. Sync it straight into Affinity, Airtable, Monday or your AI agent.
Can I monitor changes?
Yes. Turn on a Monitor and we alert you (email, Slack, webhook) when a tracked company adds or drops a technology, or when new sites start using a tool you follow.
Is the free check really free?
Yes. Anyone can run scans from this page with no account and no card. The free result reveals a sample of the detected stack; unlocking every technology on a domain, and scanning in volume, is what the paid plans and the API are for.
What a tech stack checker actually returns
Most tools read a page's scripts and stop there. We read the public surface with 395 detector signatures across 26 groups, then add the records that sit around the site: nameservers, TLS, and the mail-authentication setup. That second half is where the interesting findings usually are, because a domain's verification TXT records are left behind by the SaaS tools a company has connected, and those tools never appear in the page HTML at all.
Here is a real result for notion.com, captured 27 August 2026. A live scan of the same domain today may differ: stacks change, which is the whole reason monitoring exists.
| Group | Detected |
|---|---|
| CDN | Cloudflare |
| Hosting | Vercel |
| Framework | Next.js, Tailwind |
| DNS | Cloudflare |
| Mail auth | SPF and DMARC, policy reject |
| TLS | TLS 1.3 |
Read together: a Cloudflare edge in front of a Vercel origin, a React app, and a domain whose mail is locked down hard enough to reject spoofed sending outright. That is a deliberate, well-run setup, and you can tell without a single conversation.
If you would rather start from the technology than the company, our directory works the other way round too: browse companies by the tools they run, or wire the same data into your own stack through the technology lookup API. Tech stack detection also feeds the Quality category in our Agent Readiness scanner, which scores how well a site serves AI agents alongside human visitors.
Get started
See the stack behind any company
Free scan on any domain. The full stack, funding and founders are on Pro Mini ($5/mo) or one API call away.
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