# Company list builder API for your agent Company list builder API for an agent: it sends filters such as industry, size, country or technology to a catalog endpoint and reads company name, domain and industry back. Several providers sell the call, so the agent tries the cheapest first. You pay per call, and a failed call costs nothing. ## What this does A list builder answers a query, not a name. You describe the firms you want by industry, size, country or the tools they run, and the provider returns the matches. The output is the top of a funnel: a table of companies your agent can then enrich, score or look up people at. The providers differ in the filters they offer. One searches by technology stack and hiring signals, one by headcount and headquarters, one takes a SQL clause, and one takes its own query language. The right choice follows the filter you care about most. You give: filters such as industry, size, country or technology. Example: software companies in the US with 50 to 200 employees that use Stripe. ## What differs between providers - TheirStack (theirstack-companies-search): filters by industry, country, employee count, revenue, funding, technology stack and hiring signals, with 1 to 25 results per page. - FullEnrich (fullenrich-api-company-search): filters by name, domain, industry, headquarters, headcount, keywords or founding year, and bills per company returned. - The Companies API (thecompaniesapi-companies-post): runs a segmentation search with a query, a page and a size, and bills per company returned. - People Data Labs (people-data-labs-company-search-get): takes a SQL WHERE clause or an Elasticsearch query as JSON and returns full company records. - Aviato (aviato-company-search): takes a query in the Aviato query language with a filters array and returns a count plus the matching companies. ## Before you start - Start narrow. Each company returned is billed, so a query that returns thousands costs real money. Set a limit and widen it once the sample looks right. - Check the filter names on the endpoint page. They differ per provider, and a misspelled filter returns everything or nothing. - Plan the next step before you search. A list of domains feeds company enrichment, email-format lookups and people search. ## Prompt Use looot to build a list of software companies in the US with 50 to 200 employees that use Stripe, and return name, domain and headcount for each. 1. Set up https://looot.ai/skill.md. 2. Search the catalog for each step and check its price before you call. 3. Run the cheapest endpoint that fits. 4. Show the results as a table and the total cost. ## Steps and providers - Search companies by filters: theirstack, fullenrich, thecompaniesapi, people-data-labs, aviato. 1 call per search. ## What comes back - Company name and domain - Industry and country - Employee count - Matching technologies and jobs - LinkedIn page ## The request and what comes back Each run is one POST to /v1/runs with an endpoint id and an input. These are illustrative calls with generic values. The run's result holds the provider's own fields. - TheirStack: {"endpointId":"theirstack-companies-search","input":{"limit":10,"company_country_code_or":["US"]},"wait":30} ## How do I build a list of companies by industry and size? Describe the segment to your agent, for example software firms in the US with 50 to 200 employees. It picks a provider that supports those filters, runs the search with a limit and returns a table of companies. ## Can I find companies that use a specific technology? Yes, with the providers that filter by tech stack. One of them also filters by hiring signals, so you can find firms that use a tool and are hiring for it. ## How many companies can one call return? It depends on the provider. One caps a page at 25 companies, another at 62 through looot, and each result is billed. Your agent pages through the results until it has the number you asked for. ## What happens after the list? The list is rows of companies with domains. Enrich them with company data, look up the email format, then find the people. Each step is its own call and its own price. ## Is the list complete? No provider covers every company. Coverage is better for larger firms and in the US. Compare the first page from two providers before you commit to one. ## How much does one search cost? You pay per call, and the price depends on the provider your agent picks. This page reads the cheapest live price from the catalog and shows no number when the catalog is unreachable. ## Do I pay when a company list builder call fails? No. A call that fails at the provider costs nothing, and your agent can retry it or send it to another provider. ## Do I need an account with each company list builder provider? No. One looot key reaches every provider in the catalog. You top up once, and each call is billed at the price shown before it runs. ## How do I call company list builder from code? Send a POST to /v1/runs with the endpoint id, the input and a new idempotency key, and your looot token in the Authorization header. With wait set to 30, the answer comes back in the response when the run ends within 30 seconds. Otherwise poll GET /v1/runs/. ## Can I run company list builder on a schedule? That needs scheduled runs, not available yet. Run it by hand whenever you want fresh results. ## Do I pay while my agent is idle? No. looot bills per call, and nothing runs while your agent is idle. ## Related pages - /use-cases/enrich-a-company - /use-cases/job-postings-api - /use-cases/find-professional-emails ## Last reviewed 2026-10-04. The cost per 1,000 search runs is read live from the catalog on the web page.