I can tell you Stripe uses Greenhouse for hiring before they have posted a job listing. I can tell you GitHub runs Zendesk for support and Marketo for marketing automation. All from a single DNS query.
Every domain broadcasts its infrastructure to the world through DNS records, SSL certificates, and HTTP headers. Most people never look. I built DomainIntel — a free API that reads all of it in one call. No API key, no signup.
Try it on your own company right now:
curl "https://domainintel.vercel.app/api/lookup?domain=yourcompany.com"
Here is what it found on two companies everyone knows.
Stripe.com: lean stack, strict security
Mail provider: Google Workspace
SPF record reveals their outbound email stack:
-
spf1.stripe.com— transactional email (their own infrastructure) -
greenhouse-outbound-mail.stripe.com— Greenhouse (applicant tracking for hiring) -
_spf.qualtrics.com— Qualtrics (surveys and feedback collection)
Three services. That is a deliberately lean setup for a company processing billions in payments.
DMARC policy: p=reject — the strictest setting possible. Any email claiming to be from stripe.com that fails authentication gets rejected outright, never delivered. This is what you want to see from a company handling your payment data.
GitHub.com: massive footprint, softer security
Mail provider: Microsoft 365
SPF record tells a very different story:
-
spf.protection.outlook.com— Microsoft 365 (primary email) -
_netblocks.google.com— Google (likely legacy or marketing) -
mail.zendesk.com— Zendesk (customer support) -
_spf.salesforce.com— Salesforce (CRM) -
servers.mcsv.net— Mailchimp (newsletters) -
mktomail.com— Marketo (marketing automation) -
sendgrid.net— SendGrid (transactional email)
Seven authorized email senders. Each one is a potential phishing vector — an attacker who compromises any of these services can send email that passes GitHub's SPF checks. This is the tradeoff of a large enterprise stack: more capability, more surface area.
DMARC policy: p=quarantine — suspicious emails get flagged but not rejected. Less strict than Stripe. For a company that is the target of constant phishing campaigns (fake GitHub security alerts are one of the most common phishing templates), this is a notable choice.
WHOIS: MarkMonitor registrar (the enterprise-grade registrar used by most Fortune 500 companies). Domain age: 18+ years, created October 2007.
SSL: Sectigo certificate with 75 days until expiry.
The comparison matters
Stripe authorizes 3 email senders with a reject policy. GitHub authorizes 7 with a quarantine policy. This is not random — it reflects fundamentally different security philosophies. Stripe optimizes for minimum attack surface. GitHub optimizes for operational flexibility at the cost of a wider trust perimeter.
If you were evaluating either company as a vendor, this single API call tells you more about their security posture than their marketing page does.
A practical walkthrough: vendor evaluation
Say you are evaluating a B2B SaaS company as a potential vendor. You run their domain:
curl "https://domainintel.vercel.app/api/lookup?domain=example-vendor.com"
What to look for:
- Google Workspace or Microsoft 365 in the mail providers — real company with proper email infrastructure
- Marketo or HubSpot in SPF — they have a marketing team, likely 50+ employees
-
DMARC set to
noneor missing — red flag, not protecting against email spoofing - SSL certificate expiring in under 30 days — operational hygiene issue
- Domain age under 1 year — proceed with extra caution
One call, 5 data points, a much clearer picture than a LinkedIn search.
Connect it
REST API (no auth, free):
curl "https://domainintel.vercel.app/api/lookup?domain=stripe.com"
MCP server for Claude, Cursor, or VS Code — add to your config:
{
"mcpServers": {
"domainintel": {
"url": "https://domainintel.vercel.app/api/mcp"
}
}
}
5 tools available: whois_lookup, dns_lookup, ssl_check, tech_stack, full_report
Free. No API key. Try it on any domain.