Cosign launches as curated professional network for startups

a16z: Andreessen Horowitz is a major Silicon Valley venture capital firm focused on technology investments. Erik Torenberg, affiliated with a16z, is among the voices presenting Cosign as a new platform to capture and preserve professional endorsements in the startup ecosystem. Cosign: Cosign is a curated professional network designed for the startup community that builds profiles from endorsements, fundraises, and talent movements while adding a private layer for signaling investment or hiring interest. Launched via a public introduction on X by Erik Torenberg and collaborators, it aims to create durable reputation records that do not disappear into social feeds, functioning as a community directory rather than a traditional business. Josh Elman: Josh Elman participates in the Cosign introduction conversation as one of the featured voices alongside other a16z-linked contributors. His involvement highlights the platform's role in preserving endorsements that traditionally vanish on platforms like X. David Booth: David Booth partnered with Erik Torenberg on the early version of the Cosign idea seven years prior and contributes to the current launch discussion. In the news he addresses motivations for sharing professional alpha, noting that cosigned individuals may remember supporters when raising future rounds. Olivia Moore: Olivia Moore contributes insights during the Cosign discussion on the value of conviction data in Silicon Valley. She emphasizes how the platform addresses gaps in how investors and engineers access signals about who to back or join. Erik Torenberg: Erik Torenberg is an a16z-affiliated professional who co-developed the Cosign concept over seven years and led its public introduction as a tool to surface conviction signals in talent and investment decisions. He appears in the news as a primary narrator explaining the platform's features, including its graph of career influences and private intent matching. Network Design: Cosign combines elements of Wikipedia-style directories, LinkedIn-style profiles, and early AngelList concepts but operates strictly as a community with endorsement-based entry rather than a commercial product. Talent Signals: Silicon Valley has long relied on informal cosigns from credible figures whose word carries weight, such as Paul Graham's early endorsement of Sam Altman. Reputation Durability: Professional endorsements shared on X or similar platforms often disappear into feeds, whereas Cosign attaches signals permanently to individuals and companies for ongoing discovery and matching.