CTScout

Who is behind a domain?

When a company gets a website certificate with its name checked by the issuer, that certificate lands in the public Certificate Transparency logs. CTScout reads those logs, matches the names to the legal-entity register (GLEIF), and answers two questions: which organization stands behind a domain, and which domains an organization holds certificates for. From public data only.

A company name links its answer page, no key needed. A domain is searched through the API with your free key.

Look something up

One page per organization: its domains, the vendors confirmed on them, and where the numbers come from.

Plug it into your agent

A hosted MCP server and a JSON API. Free key from the box below, no account.

Read the research

Three notes on what six months of certificates can and cannot say, with the data behind each.

How it works

  1. A certstream pipeline ingests ~2.5M certificate events per week
  2. OV/EV certificates carry the issuing organization's name; DV-only certificates (Let's Encrypt, ZeroSSL) name no one and are out of scope
  3. Apex domains are extracted, deduplicated and aggregated by organization: … org-domain pairs across … organizations
  4. Names that resolve to exactly one GLEIF record get an LEI and an answer page; the research notes report how often that works and how it fails

Not a cyber-risk-scoring tool — see LIMITATIONS.

Tiers

FreePro
Successful lookups10 / day3,000 / month
ResultsTop 5Top 25
History windowLast 90 daysUp to 12 months
Deep-dive jobs (async)—20 / day
DataDaily snapshotDaily snapshot
Customer listsFirst 100 rowsFull list
Price$0$49 / month — subscribe, the key comes by email within a day

Answer pages, research notes, open data and the LEI endpoints need no key at all. A lookup counts only when it returns a result; an empty answer is free, and a runaway script is stopped by a separate per-day request guard. Pro is paid monthly by card through Stripe and the key is sent by hand to the email on the receipt; need more than 3,000, or the whole dataset? Email. Terms and privacy.

Get a free API key

No email. No account.

Save this key — it cannot be retrieved again.