# AI assistants tools used by Professional Services companies

usedby lists 18 Professional Services companies using 4 AI assistants tools. The most used is Claude: 13 of the 18 Professional Services companies on usedby, every proof level counted. These are counts of the companies usedby tracks, not a market share. Data as of 2026-10-25.

## Largest and best-proven users

Two labelled views of the same companies. Neither is a score.

### Largest companies

By employee range. Size known for 13 of 18.

| Company | Proof | Employees | Tools | Last check |
|---|---|---|---|---|
| [Thomson Reuters](https://www.usedby.ai/companies/thomson-reuters.md) | Confirmed | 10,001+ | Claude, Gemini | 2026-10-19 |
| [PwC](https://www.usedby.ai/companies/pwc.md) | Confirmed | 10,001+ | Claude, ChatGPT | 2026-10-18 |
| [Bain & Company](https://www.usedby.ai/companies/bain-company.md) | Observed | 10,001+ | ChatGPT | Not dated |

### Strongest proof

Confirmed or declared: 9 of 18. This view filters what you read, never what is counted.

| Company | Proof | Employees | Tools | Last check |
|---|---|---|---|---|
| [Harvey](https://www.usedby.ai/companies/harvey.md) | Confirmed | 1,001–5,000 | Claude, Gemini | 2026-10-22 |
| [Docusign](https://www.usedby.ai/companies/docusign.md) | Confirmed | 5,001–10,000 | Gemini | 2026-10-19 |
| [Freshfields](https://www.usedby.ai/companies/freshfields.md) | Confirmed | Unknown | Gemini | 2026-10-19 |

## Ranking

Tools ranked by the companies of the 18 Professional Services companies on usedby that use them. Each company counts once per tool, at its strongest proof. Ties go to more confirmed, then declared, then observed companies.

| # | Tool | Companies | Confirmed | Declared | Observed | Job posts only | Last check |
|---|---|---|---|---|---|---|---|
| 1 | [Claude](https://www.usedby.ai/tools/claude.md) | 13 | 5 | 0 | 5 | 3 | 2026-10-25 |
| 2 | [Gemini](https://www.usedby.ai/tools/gemini.md) | 5 | 5 | 0 | 0 | 0 | 2026-10-19 |
| 3 | [ChatGPT](https://www.usedby.ai/tools/chatgpt.md) | 3 | 0 | 0 | 3 | 0 | Not dated |
| 4 | [Microsoft Copilot](https://www.usedby.ai/tools/microsoft-copilot.md) | 1 | 0 | 0 | 0 | 1 | 2026-10-21 |

## Customers per tool

Every line is a customer, at one of three proof levels: confirmed (a case study, a named quote, a press release, or the company's own public account of using the tool (its own site, or a post by one of its executives, VP or above)), observed (the vendor shows the company on its own pages) or signal (a job post shows the company's employees use the tool, the weakest proof). A line the company declared to usedby itself, or that it lists as a sub-processor on its own legal page, is marked declared. A signal is never a case study or a vendor listing. Strongest proof first. "Last check" is the later of the line's re-verification and its latest capture.

| Tool | Company | Proof | Source | Last check |
|---|---|---|---|---|
| Claude | [PwC](https://www.usedby.ai/companies/pwc.md) | Confirmed | [claude.com](https://claude.com/customers/pwc-qa), captured 2026-10-18 | 2026-10-18 |
| Claude | [Braintrust](https://www.usedby.ai/companies/braintrust-usebraintrust-com.md) | Confirmed | [claude.com](https://claude.com/customers/braintrust), captured 2026-10-18 | 2026-10-18 |
| Claude | [Fountain](https://www.usedby.ai/companies/fountain.md) | Confirmed | [claude.com](https://claude.com/customers/fountain), captured 2026-10-18 | 2026-10-18 |
| Claude | [Steno](https://www.usedby.ai/companies/steno.md) | Confirmed | [claude.com](https://claude.com/customers/steno), captured 2026-10-18 | 2026-10-18 |
| Claude | [Harvey](https://www.usedby.ai/companies/harvey.md) | Confirmed | [harvey.ai](https://www.harvey.ai/blog/how-harvey-is-building-a-frontier-marketing-org), captured 2026-10-22 | 2026-10-22 |
| Claude | [BCG](https://www.usedby.ai/companies/bcg.md) | Observed | [anthropic.com](https://anthropic.com/customers) | Not dated |
| Claude | [Thomson Reuters](https://www.usedby.ai/companies/thomson-reuters.md) | Observed | [anthropic.com](https://anthropic.com/customers) | Not dated |
| Claude | [EvenUp](https://www.usedby.ai/companies/evenup.md) | Observed | [claude.com](https://claude.com/customers), captured 2026-10-12 | 2026-10-12 |
| Claude | [Spellbook](https://www.usedby.ai/companies/spellbook.md) | Observed | [claude.com](https://claude.com/customers), captured 2026-10-12 | 2026-10-12 |
| Claude | [Legora](https://www.usedby.ai/companies/legora.md) | Observed | [anthropic.com](https://anthropic.com/customers) | Not dated |
| Claude | [Gusto](https://www.usedby.ai/companies/gusto.md) | Signal (job post) | [job-boards.greenhouse.io](https://job-boards.greenhouse.io/gusto/jobs/8168907), captured 2026-10-20 | 2026-10-20 |
| Claude | [Xero](https://www.usedby.ai/companies/xero.md) | Signal (job post) | [jobs.ashbyhq.com](https://jobs.ashbyhq.com/xero/29b71925-11ff-4ed1-b515-50daab030565), captured 2026-10-25 | 2026-10-25 |
| Claude | [Pennylane](https://www.usedby.ai/companies/pennylane.md) | Signal (job post) | [jobs.ashbyhq.com](https://jobs.ashbyhq.com/pennylane/fd74cf0b-6d41-4a75-97b7-ab72164ef3c7), captured 2026-10-22 | 2026-10-22 |
| Gemini | [Docusign](https://www.usedby.ai/companies/docusign.md) | Confirmed | [cloud.google.com](https://cloud.google.com/transform/101-real-world-generative-ai-use-cases-from-industry-leaders), captured 2026-10-19 | 2026-10-19 |
| Gemini | [Thomson Reuters](https://www.usedby.ai/companies/thomson-reuters.md) | Confirmed | [cloud.google.com](https://cloud.google.com/transform/101-real-world-generative-ai-use-cases-from-industry-leaders), captured 2026-10-19 | 2026-10-19 |
| Gemini | [Freshfields](https://www.usedby.ai/companies/freshfields.md) | Confirmed | [cloud.google.com](https://cloud.google.com/transform/101-real-world-generative-ai-use-cases-from-industry-leaders), captured 2026-10-19 | 2026-10-19 |
| Gemini | [Markups.ai](https://www.usedby.ai/companies/markups-ai.md) | Confirmed | [cloud.google.com](https://cloud.google.com/transform/101-real-world-generative-ai-use-cases-from-industry-leaders), captured 2026-10-19 | 2026-10-19 |
| Gemini | [Harvey](https://www.usedby.ai/companies/harvey.md) | Confirmed | [cloud.google.com](https://cloud.google.com/transform/101-real-world-generative-ai-use-cases-from-industry-leaders), captured 2026-10-19 | 2026-10-19 |
| ChatGPT | [Bain & Company](https://www.usedby.ai/companies/bain-company.md) | Observed | [chat.openai.com](https://chat.openai.com/customers) | Not dated |
| ChatGPT | [BCG](https://www.usedby.ai/companies/bcg.md) | Observed | [chat.openai.com](https://chat.openai.com/customers) | Not dated |
| ChatGPT | [PwC](https://www.usedby.ai/companies/pwc.md) | Observed | [chat.openai.com](https://chat.openai.com/customers) | Not dated |
| Microsoft Copilot | [OneTrust](https://www.usedby.ai/companies/onetrust.md) | Signal (job post) | [job-boards.greenhouse.io](https://job-boards.greenhouse.io/onetrust/jobs/8256207), captured 2026-10-21 | 2026-10-21 |

## Method

Public customer lines of active AI assistants tools at companies classified in Professional Services. No software vendor had to be left out. Company mix by strongest proof: 9 confirmed, 0 declared, 5 observed and 4 signals.

## Questions

### Which AI assistants tools do Professional Services companies use most?

Claude leads: 13 of the 18 Professional Services companies on usedby that use AI assistants tools use it. Next: Gemini (5), ChatGPT (3), and Microsoft Copilot (1).

### How many Professional Services companies use AI assistants tools?

18 Professional Services companies on usedby use at least one of 4 AI assistants tools. It counts the companies usedby tracks.

### What proof backs these lines?

Of the 18 companies, each counted at its strongest proof: 9 confirmed, 0 declared, 5 observed and 4 known from a job post.

### How does usedby build this ranking?

usedby counts each Professional Services company once per tool, from public proof: case studies, press releases, the company's own site or its declaration to usedby, vendor customer pages and job posts. Every line shows its proof and the date usedby last checked it.

Industry page: https://www.usedby.ai/companies/industry/professional-services.md · Category page: https://www.usedby.ai/tools/category/ai-assistants.md

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Source: https://www.usedby.ai/companies/industry/professional-services/ai-assistants · How we check: https://www.usedby.ai/methodology