Blackletter is a law firm for startups and growth-stage companies that want corporate, commercial, financing, M&A, and employment matters quoted as a fixed fee before work begins. On November 9, 2026 it announced a $6 million seed round led by Lerer Hippeau, with Seven Stars, Maple VC, Garage Capital, and Ripple Ventures participating, along with Cohere founders Aidan Gomez, Ivan Zhang, and Nick Frosst, Twelve Labs CEO Jae Lee, and Adaption Labs CEO Sara Hooker. A Lerer Hippeau spokesperson told Business Insider the investment was the firm's first in legal. The capital is for further development of BlackletterOS, the software that runs client matters, and for hiring lawyers and engineers. A senior lawyer handles every matter, makes the judgment calls, and stays reachable in Slack, by email, or by phone. Calls and correspondence are not billed. BlackletterOS stores what the firm already knows about a client and carries each file from intake to delivery, and the firm says it can flag a recurring problem, such as a standard clause that keeps delaying deals, before a lawyer starts from a blank page. With the fee set in advance, finishing the work faster does not increase the bill. Co-founders Jonathan Rosenbluth and David Stewart previously held product and engineering leadership roles at Cohere. Rosenbluth, the CEO, has a Harvard Law degree, worked at McKinsey, and was an early hire at Cohere. Avi Brudner was chief operating officer of Blue J, an AI company serving tax professionals. Since leaving stealth in June 2026, the firm reports more than 75 clients, among them Ada, Crux, Fanatics Betting & Gaming, and Twelve Labs, and says it advised WindBorne Systems on a $37 million Series B. The firm is based in New York and Toronto, with U. S. legal services through Blackletter Legal LLP and Ontario services through Blackletter Professional Corporation.