Who believed in you first? Silicon Valley runs on that question. a16z's Erik Torenberg, David Booth, Josh Elman, and Olivia Moore on Cosign: Cosign is a curated professional network for the startup community. Profiles are built from endorsements, fundraises, and talent moves, with a private layer to signal who you'd fund or hire. Erik ran a small version of this seven years ago, emailing a few hundred people and asking each for one person to watch. One of the answers was Russell Kaplan, then a 22-year-old engineer at Tesla, now president of Cognition. Olivia on why this matters: "The most valuable data in all of Silicon Valley is who has conviction in who." Investors chase it every day and still struggle to find it. An engineer choosing between five offers has almost no way to get it at all. Paul Graham cosigned Sam Altman in 2009, six years before OpenAI was founded. Ryan Hoover cosigned Erik early at Product Hunt. Silicon Valley has always run on cosigns from people whose word carries weight, and until now nobody kept the record. The conversation closes on the question of why anyone would share their alpha. David's answer is that the person you cosign today is the one raising a round in two years, and when they do, they remember who believed in them first. 0:55 Twitter as a credential 3:05 Silicon Valley is a race to discover talent 4:10 The 3 questions on every Cosign profile 5:45 The email that found Russell Kaplan at 22 6:15 Conviction is the scarcest data 9:50 Why Cosign is free and strictly positive 11:05 Seeing things before the market does 13:00 Sending private "I'd fund them" signals 18:35 Endorsements that don't vanish 23:05 Recognition for the unsung engineer 29:40 Building LinkedIn Jobs in 2004 34:25 AI made human endorsement scarce 36:45 Why nobody has disrupted LinkedIn 42:10 Your Cosign profile may already exist 46:25 Silicon Valley always ran on cosigns 48:10 "Why would I give away my alpha?" YouTube: piped.video/-ywZlfznTa4 @eriktorenberg @david__booth @joshelman @omooretweets

MTS AI 50 Live on Cosign cosign.co/lists/mtslive/ai-f…

Excited to introduce @Cosign: the curated professional network for the startup community: cosign.co Our goal is to create the following: - A comprehensive startup directory of investors, companies, and operators, including what they worked on and who they worked on it with. - Cosign graph: Who shaped your career? Who were you actually in the trenches with? Who would work with you again? Who thinks you’re someone to watch? - Durable reputation: Great endorsements happen every day on X and disappear into the feed. Cosign attaches those signals permanently to people and companies. - Discovery: Who are the best fintech angels? Which AI companies should I watch? Who are the best designers? - Intent network: Privately signal “I’d invest in them,” “I’d hire them,” “I’d work with them,” or eventually even “I’d acquire this company.” Match people when interest exists on both sides. Imagine if Wikipedia, LinkedIn, and OG AngelList had a baby. Though Cosign is a community, not a business. In order to join, you need to be cosigned. Or you can apply directly. David Booth and I started this idea 7 years ago but didn’t have the firepower to make it work. Now we do. No one has really touched LinkedIn in 20 years. Excited to take a swing. cosign.co

Excited to introduce @Cosign: the curated professional network for the startup community: cosign.co Our goal is to create the following: - A comprehensive startup directory of investors, companies, and operators, including what they worked on and who they worked on it with. - Cosign graph: Who shaped your career? Who were you actually in the trenches with? Who would work with you again? Who thinks you’re someone to watch? - Durable reputation: Great endorsements happen every day on X and disappear into the feed. Cosign attaches those signals permanently to people and companies. - Discovery: Who are the best fintech angels? Which AI companies should I watch? Who are the best designers? - Intent network: Privately signal “I’d invest in them,” “I’d hire them,” “I’d work with them,” or eventually even “I’d acquire this company.” Match people when interest exists on both sides. Imagine if Wikipedia, LinkedIn, and OG AngelList had a baby. Though Cosign is a community, not a business. In order to join, you need to be cosigned. Or you can apply directly. David Booth and I started this idea 7 years ago but didn’t have the firepower to make it work. Now we do. No one has really touched LinkedIn in 20 years. Excited to take a swing. cosign.co

Excited to introduce @Cosign: the curated professional network for the startup community: cosign.co Our goal is to create the following: - A comprehensive startup directory of investors, companies, and operators, including what they worked on and who they worked on it with. - Cosign graph: Who shaped your career? Who were you actually in the trenches with? Who would work with you again? Who thinks you’re someone to watch? - Durable reputation: Great endorsements happen every day on X and disappear into the feed. Cosign attaches those signals permanently to people and companies. - Discovery: Who are the best fintech angels? Which AI companies should I watch? Who are the best designers? - Intent network: Privately signal “I’d invest in them,” “I’d hire them,” “I’d work with them,” or eventually even “I’d acquire this company.” Match people when interest exists on both sides. Imagine if Wikipedia, LinkedIn, and OG AngelList had a baby. Though Cosign is a community, not a business. In order to join, you need to be cosigned. Or you can apply directly. David Booth and I started this idea 7 years ago but didn’t have the firepower to make it work. Now we do. No one has really touched LinkedIn in 20 years. Excited to take a swing. cosign.co

a16z's @david__booth and @katiesquestions on how Cosign is different from LinkedIn: Katie Goldstein: "It's LinkedIn plus AngelList and Wikipedia all had a baby. It's this reputation layer that sits over it that is really the most meaningful information." "I curate my own LinkedIn, and let's be honest, I try to make myself sound really impressive. But more than anything, I wanna know what I think about other people and also what other people think of me." David Booth: "I don't think the connection strength represents anything anymore. A professional reputation is really about the strength of what relationships you have, and that's simply not represented there at all." "People who are focused on identifying potential before the market. What is your CV that demonstrates your ability to do that? It's certainly not LinkedIn." @cosign @a16z

so happy with @cosign's launch, this past month building it from scratch has been the craziest of my life. we're hiring engineers! if you want to come help build it, take a look at drops.mts.now, build a drop (themed around cosign/social networks ideally), post about, and dm me the git with a transcript of the agent conversation used to built it as well. the best engineers are creative, decisive, quick, and empathetic. build something that shows that off and i promise to at minimum respond (+everyone who posts something will be let into cosign!)

Who are the ppl in your career who took a chance on you? Who either put their time, reputation, or even money on the line to open doors for you?

Who are the ppl in your career who took a chance on you? Who either put their time, reputation, or even money on the line to open doors for you?

One of my favorite features of @cosign is the private signal feature. LinkedIn connections are hard to parse. An X follow can mean a lot of things. A DM is high friction. On Cosign you can passively signal private intent: would meet, would fund, would work with, etc, and get introduced if there's mutual interest.

Excited to introduce @Cosign: the curated professional network for the startup community: cosign.co Our goal is to create the following: - A comprehensive startup directory of investors, companies, and operators, including what they worked on and who they worked on it with. - Cosign graph: Who shaped your career? Who were you actually in the trenches with? Who would work with you again? Who thinks you’re someone to watch? - Durable reputation: Great endorsements happen every day on X and disappear into the feed. Cosign attaches those signals permanently to people and companies. - Discovery: Who are the best fintech angels? Which AI companies should I watch? Who are the best designers? - Intent network: Privately signal “I’d invest in them,” “I’d hire them,” “I’d work with them,” or eventually even “I’d acquire this company.” Match people when interest exists on both sides. Imagine if Wikipedia, LinkedIn, and OG AngelList had a baby. Though Cosign is a community, not a business. In order to join, you need to be cosigned. Or you can apply directly. David Booth and I started this idea 7 years ago but didn’t have the firepower to make it work. Now we do. No one has really touched LinkedIn in 20 years. Excited to take a swing. cosign.co

@sarahdingwang and @aleximm - thanking the new media team for helping the founders they invest in go viral. So many amazing people on this new media team @eriktorenberg has assembled grinding every day to get out blogs, podcasts, videos, communities and comms that can are activated on demand like a tidal wave of support for founders. I would have killed for this capacity in my CMO days. So impressed by these people! ✨

Started a list of top German founders in the US. Increasing number of insane people coming here. Send me whoever is missing.

Who believed in you first? Silicon Valley runs on that question. a16z's Erik Torenberg, David Booth, Josh Elman, and Olivia Moore on Cosign: Cosign is a curated professional network for the startup community. Profiles are built from endorsements, fundraises, and talent moves, with a private layer to signal who you'd fund or hire. Erik ran a small version of this seven years ago, emailing a few hundred people and asking each for one person to watch. One of the answers was Russell Kaplan, then a 22-year-old engineer at Tesla, now president of Cognition. Olivia on why this matters: "The most valuable data in all of Silicon Valley is who has conviction in who." Investors chase it every day and still struggle to find it. An engineer choosing between five offers has almost no way to get it at all. Paul Graham cosigned Sam Altman in 2009, six years before OpenAI was founded. Ryan Hoover cosigned Erik early at Product Hunt. Silicon Valley has always run on cosigns from people whose word carries weight, and until now nobody kept the record. The conversation closes on the question of why anyone would share their alpha. David's answer is that the person you cosign today is the one raising a round in two years, and when they do, they remember who believed in them first. 0:55 Twitter as a credential 3:05 Silicon Valley is a race to discover talent 4:10 The 3 questions on every Cosign profile 5:45 The email that found Russell Kaplan at 22 6:15 Conviction is the scarcest data 9:50 Why Cosign is free and strictly positive 11:05 Seeing things before the market does 13:00 Sending private "I'd fund them" signals 18:35 Endorsements that don't vanish 23:05 Recognition for the unsung engineer 29:40 Building LinkedIn Jobs in 2004 34:25 AI made human endorsement scarce 36:45 Why nobody has disrupted LinkedIn 42:10 Your Cosign profile may already exist 46:25 Silicon Valley always ran on cosigns 48:10 "Why would I give away my alpha?" YouTube: piped.video/-ywZlfznTa4 @eriktorenberg @david__booth @joshelman @omooretweets

Excited to introduce @Cosign: the curated professional network for the startup community: cosign.co Our goal is to create the following: - A comprehensive startup directory of investors, companies, and operators, including what they worked on and who they worked on it with. - Cosign graph: Who shaped your career? Who were you actually in the trenches with? Who would work with you again? Who thinks you’re someone to watch? - Durable reputation: Great endorsements happen every day on X and disappear into the feed. Cosign attaches those signals permanently to people and companies. - Discovery: Who are the best fintech angels? Which AI companies should I watch? Who are the best designers? - Intent network: Privately signal “I’d invest in them,” “I’d hire them,” “I’d work with them,” or eventually even “I’d acquire this company.” Match people when interest exists on both sides. Imagine if Wikipedia, LinkedIn, and OG AngelList had a baby. Though Cosign is a community, not a business. In order to join, you need to be cosigned. Or you can apply directly. David Booth and I started this idea 7 years ago but didn’t have the firepower to make it work. Now we do. No one has really touched LinkedIn in 20 years. Excited to take a swing. cosign.co