Tallowmere Counsel is a made-up service. Every company, person, number and clause is invented; the legal wording is illustrative, not legal advice. The negotiation playback is a scripted simulation and no model is called. The signatures are real ECDSA P-256 signatures over canonical JSON, and this page checks each one with the Web Crypto API in your browser.
Also in this demonstration: the founder desk · the investor desk