a16z-Backed Cosign Launches: A 'Reputation Layer' for the Startup Ecosystem

a16z · x · 2026-09-25

a16z amplified the launch of Cosign, a "reputation layer for the startup ecosystem" built on the idea "if you believe in someone early, say so."

It's a curated professional network where profiles carry attributable cosigns from people who actually worked with you — Sam Altman's example profile shows 42 cosigns for AI leadership, 36 for company building. Features include curated people/company lists, community voting on "who is defining the future of technology," and an aggregated industry watch feed tracking OpenAI, World Labs, Databricks and more. Founded by Erik Torenberg.

Related event: a16z Launches Cosign, an Endorsement Network for Startups(4 posts)→

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