Arceus Raises $17M Series A Led by Greycroft for AI-Native Legal Services

Arceus Secures $17M Series A

Arceus, a San Francisco-based AI-native law firm, has raised $17 million in Series A funding. The round was led by Greycroft.

What Arceus Does

Arceus pairs licensed attorneys with AI agents and its proprietary CounselOS platform to deliver commercial legal work — contract review, drafting, and negotiation — at flat, upfront prices for startups and fast-growing companies.

The firm guarantees standard reviews within eight hours or they are free, with most matters completed in three to five hours. Work comes in through Slack and email, while context is gathered from tools such as Salesforce, HubSpot, and Gmail.

Founded in 2026 by CEO Mac Liu, Arceus started with commercial contracts and is expanding into employment, privacy, and broader general-counsel work.

The Round

• Round type: Series A
• Amount: $17 million USD
• Lead investor: Greycroft
• Announced: October 1, 2026

Participating Investors

• Greycroft
• Craft Ventures
• South Park Commons

Why It Matters

Arceus is part of a growing category of companies applying AI to professional services delivery, where the combination of software and human expertise is used to compress turnaround times and shift pricing from hourly billing to flat fees. The firm's model — licensed attorneys supported by AI agents and a proprietary platform — targets the commercial legal needs of startups and high-growth companies, a segment that is often cost-sensitive and speed-dependent.

The eight-hour guarantee and three-to-five-hour typical completion times are notable operational commitments in legal services, where turnaround is frequently a pain point for early-stage companies negotiating contracts.

Acquisition Angle

For acquirers in legal tech, professional services, and AI-enabled workflow software, Arceus presents several points of interest:

• Proprietary platform (CounselOS) combining AI agents with licensed attorney oversight.
• Flat, upfront pricing model that differs from traditional hourly legal billing.
• Integration into customer workflows via Slack, email, Salesforce, HubSpot, and Gmail.
• Expansion path from commercial contracts into employment, privacy, and general-counsel work.

At Series A, the company has moved beyond initial traction and is funded to expand its service lines and platform. Strategic buyers may view the combination of a licensed legal practice and proprietary AI tooling as a differentiated asset, though the hybrid services-plus-software model also raises integration and regulatory considerations that acquirers would need to evaluate.

Summary

Arceus has raised a $17 million Series A led by Greycroft, with participation from Craft Ventures and South Park Commons. The San Francisco firm combines licensed attorneys with AI agents and its CounselOS platform to deliver commercial legal work at flat, upfront prices, and is expanding into employment, privacy, and broader general-counsel services.