Foundation Models (LLMs): the tools companies use

Large Language Models available via API

160 companies on usedby use at least one of the 7 tools in this category with a public customer. Claude leads with 73 companies. Then come ChatGPT (40) and Mistral (37). 10 companies run two of these tools or more. The most common pair is Claude with ChatGPT (4 companies).Latest check Oct 8, 2026: 113 of 183 public lines checked. Counts are of companies on usedby, not of the whole market: we list a company when a public page shows its AI tools.

160

companies on usedby use a tool of this category

Latest check Oct 8, 2026: 113 of 183 public lines checked

Which tool is used most

Companies per tool. A company using two tools counts for both.

Counts include job-post signals, drawn apart on each tool page.

Ranked by customers

Companies with a public line for each tool. Job-post signals count and are drawn apart in the proof bar.

Foundation Models (LLMs) tools ranked by companies on usedby
#	Tool	Customers
1	Claude	73
2	ChatGPT	40
3	Mistral	37
4	Cohere	23
5	OpenAI API	5
6	Sakana AI	3
7	Gemini	2
	Poolside	—

10 companies run two of these tools or more. The most common pair is Claude with ChatGPT, at 4 companies.

Claude73 customers

Claude is used by 73 companies on usedby, 16 confirmed by a case study, a named quote or a press release. Named customers include Atlassian, BCG, and SAP. Who uses Claude, ChatGPT vs Claude

Customer page: claude.com. Latest check of 42 of 73 lines: Oct 8, 2026.

ChatGPT40 customers

ChatGPT is used by 40 companies on usedby, 0 confirmed by a case study, a named quote or a press release. Named customers include Bill & Melinda Gates foundation, Harvard, and Walmart. Who uses ChatGPT, ChatGPT vs Claude

Latest check of 7 of 40 lines: Oct 8, 2026.

Mistral37 customers

Mistral is used by 37 companies on usedby, 34 confirmed by a case study, a named quote or a press release. Named customers include IBM, AIRBUS, and BNP Paribas. Who uses Mistral, Claude vs Mistral

Customer page: mistral.ai. Latest check of 34 of 37 lines: Oct 2, 2026.

Cohere23 customers

Cohere is used by 23 companies on usedby, 8 confirmed by a case study, a named quote or a press release. Named customers include Nvidia, Oracle, and Accenture. Who uses Cohere, Claude vs Cohere

Latest check of 21 of 23 lines: Oct 2, 2026.

Newest customers

Companies first listed by a tool of this category in the last 90 days.

No new customer yetTracking of changes on these tools' pages started on October 2, 2026. New customers appear here, dated, after two complete checks of those pages.

Most compared

Side-by-side pages with the companies behind each tool.

Questions about Foundation Models (LLMs)

Answers drawn from usedby data.

What is the most used tool in Foundation Models (LLMs)?

Claude, used by 73 of the 160 companies on usedby in this category. Then come ChatGPT (40) and Mistral (37). Who uses Claude.

Do more companies use Claude or ChatGPT?

Claude: 73 companies on usedby, against 40 for ChatGPT. 4 companies use both, counting confirmed and observed lines only.

Do companies use several tools in Foundation Models (LLMs)?

Yes: 10 of the 160 companies on usedby in this category run two or more. The most common pair is Claude with ChatGPT (4 companies).

How does usedby rank these tools?

By the number of companies with a public line for each tool, read from dated captures of vendor customer pages, case studies, press releases and job posts. Job-post signals count in the totals and are shown apart. usedby lists a company when a public page shows it, so these counts describe the companies on usedby, not the whole market.