Search ctscout by company name
ctscout_search_companyFind all apex domains owned by a company using Certificate Transparency log data. Enter an organization name to get attributed domains with certificate and subdomain counts.
Instructions
Search ctscout.dev's domain-attribution warehouse by organization name. Returns apex domains attributed to that organization based on Certificate Transparency log analysis (OV/EV cert subjects matched to entity names).
Args:
company_name (string, required): organization name. Partial matches work — 'Goldman' matches 'Goldman Sachs'. Min 2 chars, max 200.
response_format ('markdown' | 'json', default 'markdown'): output format.
Returns:
In markdown: a table of (domain, org, cert count, subdomain count).
In JSON, structured as: { "domains": [ { "org": string, // legal entity name as recorded in cert "apex_domain": string, // e.g. "gs.com" "cert_count": number, // # of certs observed for this domain "subdomain_count": number, // # of distinct subdomains "first_seen": string, // ISO 8601 timestamp "last_seen": string // ISO 8601 timestamp } ], "total": number, // total matching rows in warehouse "truncated": boolean, // true if response is capped "upgrade_hint": string, // present when truncated "source": "warehouse" | "live" // free tier = warehouse, pro = live }
Examples:
Use when: "Find all domains owned by Cloudflare" -> { company_name: "Cloudflare" }
Use when: "What domains does Goldman own?" -> { company_name: "Goldman Sachs" }
Don't use when: You have a specific domain and want to find its owner — use ctscout_lookup_domain instead.
Auth & limits:
Requires CTSCOUT_API_KEY env var. Get a free key (no email) at https://ctscout.dev.
Free tier: 10 queries/day, top 5 results from weekly snapshot.
Pro tier: unlimited queries, full result set, live enrichment.
Error handling:
HTTP 401: API key missing or invalid.
HTTP 429: daily quota exceeded — wait or upgrade.
"No domains found": try a shorter or different company name (see legal-vs-brand caveat below).
Legal-vs-brand caveat (important):
The cert subject (O field) uses LEGAL entity names, not brand names.
"Travelers Insurance" → 0 results because the legal name is "The Travelers Companies, Inc."
"Hartford Financial" → 0 results; legal names are "Hartford Fire Insurance Company" or "The Hartford Financial Services Group".
If a brand-name search returns nothing, retry with variants like "X Companies", "X Group", "X Inc", "X Corporation", or "The X". The empty-result markdown output includes these suggestions automatically when the input looks brand-shaped.
Coverage caveat:
Best for established US/EU tech companies with OV/EV certs (~5,976 entities indexed).
Limited coverage on small private companies, cyber MGAs, and entities using only DV (Let's Encrypt) certs.
See https://ctscout.dev for current coverage map.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| company_name | Yes | Company / organization name to search for. Partial matches work (e.g. 'Goldman' matches 'Goldman Sachs'). Case-insensitive. | |
| response_format | No | Output format: 'markdown' for human-readable summary, 'json' for the raw API response (useful for programmatic processing). | markdown |