Free Tech Stack Checker
3 free checks a day, no sign-up. Enter a domain to see the hosting, frameworks, analytics, payments and mail setup behind it. Try with
- No credit card
- DNS and mail records too
- Pay as you go after
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It detects CDN, hosting, frameworks, CMS, analytics, payments, auth and support tooling from the public site, using 395 detector signatures across 26 groups. It reads DNS nameservers, TLS and the mail authentication records SPF, DKIM and DMARC.
| Group | Detected | What it means |
|---|---|---|
| CDN | Cloudflare | Edge in front of the origin |
| Hosting | Vercel | Origin behind the Cloudflare edge |
| Framework | Next.js, Tailwind | React app, utility CSS |
| DNS | Cloudflare | dana + woz nameservers |
| Mail auth | SPF and DMARC, policy reject | Spoofed mail is rejected outright |
| TLS | TLS 1.3 | Current protocol, no legacy fallback |
Why know what a company runs
Know what they run before you pitch
Knowing a prospect runs Stripe tells you what to lead with, and knowing they run your competitor tells you the deal is a replacement.
Watch a rival re-platform
A stack change is a decision taken weeks before any announcement. StartupHub Monitor alerts when a tracked company adds or drops a technology.
Read the operational hygiene
Mail authentication shows how a company is run. The absence of error tracking says more than a deck will.
How the StartupHub.ai checker works
- Step 1
Enter a domain
Enter a domain such as example.com, free with no signup.
- Step 2
The site is read
The checker detects CDN, hosting, frameworks, CMS, analytics, payments, auth and support tooling from the public site using 395 detector signatures across 26 groups. It also reads DNS nameservers, TLS and the mail authentication records SPF, DKIM and DMARC.
- Step 3
Read the stack
For example notion.com captured 27 August 2026 showed Cloudflare CDN, Vercel hosting, Next.js and Tailwind, Cloudflare DNS, SPF and DMARC with policy reject, and TLS 1.3. The free result reveals three technologies and the full stack comes with a paid plan or over the API.
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
Keep using it
Free
10 scans a day
On this page, no card.
Tech stack data wherever you work
Access it from an AI agent over MCP, over the REST API, as a directory filter, and as a monitor that alerts on changes.
MCP and AI agents
The scan_company_technology tool runs the same scan over MCP in Claude, ChatGPT, Cursor and n8n.
> Add the MCP server https://www.startuphub.ai/api/v1/mcp (name: StartupHub.ai) and use its scan_company_technology tool to look up what a company runs before I write to them.
> What does notion.com run?
● startuphub - scan_company_technology (MCP)
⎿ hosting: Vercel, cdn: Cloudflare, framework: Next.js
● notion.com runs Next.js on Vercel behind Cloudflare. DMARC is set to reject.
Claude Code
Claude Code connects to our MCP server once and can then look a domain up mid-task. The scan_company_technology tool runs the same scan over MCP.
Set up in Claude Code{
"domain": "udio.com",
"company": { "name": "Udio" },
"hosting": "Vercel",
"payments": ["Stripe", "Recurly"]
}Technology API
The API takes a domain per call at 1 credit or $0.001 per lookup with x402 and no account, priced per scan rather than per seat.
Read the API docsPayments: Stripe, Support: Intercom
- UdioVercel
- KalshiVercel
- BrelliumVercel
Companies by technology
The directory can be filtered by technology, so a list of companies running one payment processor or one auth provider is a search.
Search the directoryTracked: suno.com
- AuthClerk
- AnalyticsSegment
- PaymentsNone detected
Find more data on the companies you care about
StartupHub.ai profiles AI startups, investors and people with funding, team and tech stack data on the site, over the REST API and over MCP.
- REST API and MCP
- Pay as you go
- Free to start
Platform
Find leads on StartupHub.ai
Search startups, investors and people then find and verify their work emails. Start free with no account needed.
Search the directoryData
Use our data API
Put startup, investor, people and email data inside your product over a REST API and pay as you go per call.
Read the API docsAI
Add StartupHub.ai to AI
Give AI assistants and agents our data over MCP. The MCP connection works in Claude, ChatGPT, Cursor and n8n.
Connect StartupHub.ai to AIWhat 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.
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
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.
Common questions about the tech stack checker.
If you do not find your answer here, reach us through our help and contact page.
Help and contactWhat 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.
