Cosign

#12 in Other

Andreessen Horowitz · 2× · last seen Sep 26, 2026

31

Momentum

Cosign is a professional network for the startup community launched by a16z (Andreessen Horowitz) through its "New Media" product team. The platform organizes reputation not through self-written profiles, but through so-called "Cosigns" – recommendations from people someone has worked with, complemented by curated lists, an industry activity feed, and job postings from the startup scene. The product is currently in public Beta and operates under its own domain cosign.co.

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