Arceus raises $17M for an AI-native law firm

The San Francisco startup pairs Slack agents with a licensed lawyer and a quoted flat fee for startup contracts.

On 1 October 2026, Arceus, also known as Arceus Legal, came out of stealth. In the company blog, founder Mac Liu introduced it as an AI-native law firm and announced $17 million in funding led by Greycroft, with Craft Ventures, South Park Commons, and others. Business Insider, Artificial Lawyer, and SiliconANGLE covered the launch the same day.

People who follow AI in law usually see a copilot sold to large firms that still bill by the hour. Arceus sells the legal work itself. Agents read the contract and draft a first pass; a licensed attorney, the company says, handles every request.

Arceus sells that service. Greycroft, Craft Ventures, and South Park Commons are named investors. Business Insider had exclusive access to the pitch deck (the slides used to raise money) and wrote that $17 million is total funding, not necessarily a single new check. The Arceus homepage also shows a Conviction logo.

First: what an AI-native law firm is

In the company’s wording, this is not a writing plugin. It is a firm that uses agents (programs that take a task and run a sequence of steps) to read the contract and draft the first version, then still delivers the work as legal practice. The site advertises professional insurance. It does not publish a policy, a limit, or a carrier.

Picture a very fast junior who never signs alone. The actual loop is different: the software pulls history from the CRM (the sales and customer database) and from email, produces a redline (the marked-up edits on the contract), and a licensed human closes it. The picture breaks if you imagine the AI speaking in court on its own. The launch is about commercial contracts: MSAs (the master services agreement), DPAs (the data-processing add-on), NDAs (confidentiality agreements), Terms of Service, and order forms. It is not litigation.

Requests, the site says, come in through Slack or email. There is no new product to log into. The CounselOS platform connects to Salesforce, HubSpot, Gmail, Slack, Google Drive, and DocuSign so it can pull prior agreements, preferences, and negotiation history before the task goes out.

Price, turnaround, and what the table says

The company says the fee is flat, quoted before work starts, with no billable hour. On the On-Demand table seen on 9 October 2026 at arceus.legal/pricing, an NDA or order-form review costs $250. A standard review of 1 to 24 pages costs $500 to $1,000. A complex review of 25 pages or more starts at $1,000. New drafting also starts at $1,000. The homepage lists the standard review as $500 per contract and 3 to 25 pages, and lists drafting as $2,000 per document, with smaller projects at $1,000 to $1,500. The /pricing list is the source for the figures; the homepage summary does not match it.

The company says a standard review takes 3 to 5 hours on average, and it guarantees 8 hours: if it runs longer, the review is free. Artificial Lawyer and SiliconANGLE repeat that turnaround promise. No one outside the firm has measured the average. In Arceus’s own copy, the guarantee applies to a standard review, not to every service.

Traction, the founder, and what we still don’t know

According to Arceus, by the launch it had reviewed more than 12,000 contracts, and its active client base had quadrupled in September 2026. It did not publish the two absolute numbers. There is no audit.

Mac Liu is not a lawyer. In an interview with Business Insider, he said he worked in product and technology at Robinhood and Anduril, founded Vultron (defense-contract software), which was sold earlier in 2026 to pWin, and hired engineers before he hired his first attorney.

RUMOR: Business Insider called the round a Series A. The Arceus blog does not use that label. The company’s valuation on the round was not disclosed. The firm’s corporate form, including whether non-lawyers can own equity in the practice, is not in the announcement. This newsroom did not test the Slack workflow or check a state bar listing.

What it is for, and what it is not

On what was announced, the service is commercial contract work in Slack, email, and a CRM. It is not litigation. It is also not a drafting app the client runs without a lawyer. The eight-hour clock, the insurance, and the licensed sign-off remain company claims. This newsroom has not tested the flow.

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First: what an AI-native law firm is

Price, turnaround, and what the table says

Traction, the founder, and what we still don’t know

What it is for, and what it is not

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