Legal engineering companies support law firms and legal departments by designing and developing products that meet requirements and solve a particular problem. The tech stack used to do this varies from company to company, with some legal engineering companies - such as Engineer.Legal - partner with specific vendors and build using their solutions. Others, such as Theory + Principle, build proprietary technology. Knowledge engineering is a sub-category of legal engineering, whereby consultants help law firms or legal departments map out and maintain the content that will sit in the back end of a product, or help to train AI models.