Endorsement
“My favorite employee.”
cosigned by someone·pulled from X·undated
- No date, so nobody can be first.
- No claim, so nothing to confirm or deny.
- Nothing a stranger can check.
Part I·The opportunity
Make the discoverer famous.
The launch film is about the person who believed first. In every line, the cosigner is the hero. The product, in launch week, flipped it. Profiles showed endorsements lifted from X, my favorite employee, would work with him again, with the cosigner as a small avatar. Nobody got known for spotting anyone.
Then the homepage changed. It now reads Believe in someone, first and Build a reputation as a Cosigner. The direction is right. What is missing is the machinery that makes it true: no date stamp on who believed first, no track record for cosigners, no lineage.
LinkedIn owns
Who exists. Titles, dates, and connections with anyone you met at a party.
Cosign can own
Who is actually good, and who believed in them first. The private reference call, made public and permanent.
There is no hipster leaderboard.
What we found on October 1, with receipts
- Elon mock data on the front door.Elon Musk, Example profile, 42 cosigns. Placeholder data on the homepage of a trust product.
- Every profile we opened was unclaimed.Created from public information and may contain inaccuracies. Claiming requires X, so anyone not on X cannot fix their own page.
- A jobs firehose.77,916 roles. First listing logged out was a warehouse picker job in Lima. The promise is through those you trust.
- An insider leaderboard.Most Cosigned reads like the team that built it.
- 14,000 people waiting outside.The waitlist is a form. Most of the energy sits outside the door with nothing to do.
- LinkedIn moved first.It shipped colleague vouching on September 23, two days before launch. Verified by a coworker is table stakes now.
And the graveyard is loud
Tap a headstone for the cause of death.
The lesson all six teach: density, scarcity that means something, and a reason to come back.
Part IV, idea B·Believer credit
The lineage tree.
A cosign compounds. Dre to Eminem to 50 Cent to the whole label. Not one person in this tree got credit for it on a profile page. Pick a line, then pick a name.
Public record, compiled from public sources on October 1, 2026, and shown here to make the mechanic legible. In the product the lineage is built from cosigns people actually gave.
Part IV, idea A·Drew's idea
Cosign the receipt, not the vibe.
Instead of great guy, you cosign a specific contribution. The thesis, the launch, the hire, the deal. The person it was about confirms it. Dated, linked to the source, on both profiles. I ran this exact flow at Rap Genius as verified annotations, which is the closest thing that exists to a cosign on a receipt.
Cosign on a receipt
Built the verified annotation program, the thing that got artists to explain their own lines on the record.
Verified by the artist himself, which is the whole point of the program
Appears on both profiles. Cannot be edited, only lapsed.
And the profile should say which kind it is
Generated
Claimed
Confirmed
Three visible tiers. Today every profile I opened sat in the first one and said so in small grey text.
Part IV, idea C·Drew's point
You cannot cosign a thousand people.
Booth said it on launch night: a cosign is intended to be scarce and expensive. Scarcity has to be enforced in the product, not requested in a tweet. Here are your twenty-five. Twenty-two are spoken for. Spend the last three.
22 of 25 active·3 left
Click an empty slot to spend a cosign.
Hard capAround 25 active. Retire one to add one.
The overlap ruleReal overlap, shared company and dates, or a one line public reason.
The yearly re-affirmOne tap. Unconfirmed cosigns quietly lapse. No public unsigning, no drama.
Ring detectionFive people only cosigning each other get discounted.
Secret cosignsSealed today, revealed at the raise or the hire. Prove you were early without giving away alpha.
The rookie cardYour first cosign, kept on your profile forever.
Part IV, idea B·The missing board
The hipster leaderboard.
Today the board ranks volume, and volume ranks the house. Rank the same idea by hit rate and it becomes the thing nobody else has: a public record of who is good at spotting people. Flip it.
Part IV, idea E·Drew's idea
Cosign for the AI era.
When someone asks an assistant whether I am legit, the answer should cite who cosigned me and for what. Signed cosigns are the ground truth an assistant can quote, and an API lets an agent check the trust layer before an intro, a hire, or a wire. Ask it something.
Part II·The players
Their own words are receipts too.
Quoted as posted, fetched October 1, 2026. This is the brief, in the words of the people who wrote it.
a16z New MediaStorytelling for the firm, its companies and the industry,
many of the firm's networks, and incubations. Offices in SF and Venice.
The Horowitz Andreessen AcademyAnnounced September 22, 2026. Full time,
in person, San Francisco, for students out of high school. $42M raised, led by a16z. Gagan Biyani leads it.
Marc Andreessen and Erik on the board.
CosignLaunched September 25, 2026. About 14k on the waitlist, about 250
lists made, 2,000 plus cosigns given in the first night.
LinkedIn, the incumbentTwenty years of resumes. Shipped colleague vouching
two days before Cosign launched, so it is paying attention. Its weak spot is signal decay, and everyone
whose work is credits instead of titles.
The first of the three asks·Part IV, idea D
The cosign.
Erik asked for a cosign, some ideas, and precisely how I would help. Everything above is the ideas. This is the cosign, recorded the way I think it should work: thirty seconds, a face and a voice, tied to one specific thing rather than an adjective. Three slots, because three is what a cosign is worth. The recommendation letter, with a face.
Recorded by the cosigner, about a specific receipt, and kept to three. A wall of these would be the thing that stopped meaning anything.
Part III·What my goal is
Why me.
I was on the early team at Rap Genius. There was no role for what I did, so I made one. I grew the community, verified artists, launched verified annotations, and was the bridge between fans and the artists themselves. That program is the closest thing that exists to a cosign on a receipt, and I have already run it once, at a company where the whole product was credit for who said what first.
At Lean Startup Machine I helped scale the workshops to six continents, launching in a new city every weekend. City by city, curator by curator, is not a theory to me. It is a job I have done roughly fifty times, and it is exactly what the LA chapter needs.
I do special projects for Rancho Humilde, one of the largest Hispanic music labels in the country, based in LA, selling out stadiums with Junior H, Fuerza Regida and Natanael Cano. A music credit is already a cosign. That roster built one of the biggest streaming genres in the United States with no LinkedIn presence at all, which is the clearest picture I know of how much reputation lives outside the resume.
I run Nagda Homes, my own construction company: more than 300 distressed properties in ten years. Before that I started the number one tutoring company on campus at Indiana University, which taught me to recruit honors students early, and I went through On Deck in NYC coming out of COVID and moderated a panel there, so I have been inside the model Cosign is rebuilding.
It is unique to have someone who can speak tech and blue collar. My superpower is being a chameleon.
This is the first role I have applied for since starting my own firm in 2016, and the first time I would move my family to SF.
What connects the ventures
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On Deck's original idea, rebuilt with a16z behind it.
What I would own
- Connective tissue across the ventures. One person who knows what the school, the network and the media team each need from the others this week.
- One launch calendar, so a Cosign feature, an Academy moment and a New Media story land together.
- Piloting programs fast: city chapters, dinners, waitlist jobs. Ops, not engineering.
- Bridging creators, music, trades and LatAm into a network that today is bootstrapped from SV.
- Protecting your time. Calendar, priorities and information flow running like clockwork.
Days 1 to 30
Week one fixes shipped or queued. LA chapter set up with a curator and a seed list. First cosign dinner booked.
Days 31 to 60
First cosign dinner held and filmed for New Media. Cosigns from the room logged on the spot. Spec for one feature agreed with the team.
Days 61 to 90
LA chapter live and repeating monthly. One feature shipped: cosign receipts or video cosigns. Playbook ready for CDMX and the next city.
Part IV, idea I·Drew's idea
The Reverse Dinner for Schmucks
Your seat at the table is the person you vouch for. Everyone brings someone they cosign and gives a sixty second intro, logged as a cosign on the spot. Filmed for New Media, it becomes a format. Cosigned, the show. Start in LA, where the only LA list on the product already is, then CDMX and Miami. One curator per city, one seed list, one dinner a month, one city page. IRL is the highest quality cosign there is.
Part IV·Week one
What I would fix on day one.
Small, respectful, and most of it ops rather than engineering, because the team is tiny and sprinting. Tap one to see the fix.
And the holes in my own ideas
| The hole | The fix |
|---|---|
| Retention, why come back | A weekly who-is-rising digest and the notification moment. Status is the reason to open it. |
| The clique | Bridge weighting, public cosigner hit rates, outsider only lists. |
| The uncosigned newcomer | A merit path where shipped work counts, plus open to cosign requests to people you worked with. |
| Negative signal | No public unsigning. Cosigns lapse at the yearly re-affirm. |
| Legal and HR references | Cosigns are personal, not company. A podcast shoutout, not an HR letter. |
| Gaming and buying | The overlap rule, monthly caps, ring detection. |
| Deepfaked video | Recorded in app only, signed on the device, tied to a verified account. |
| The a16z conflict | Open data and a neutral feel. Other firms build lists too. Wikipedia, not a CRM. |
| Cold start outside SF | Phone login beside X, Spanish onboarding, WhatsApp invites, an ambassador per world. |
| Your attention | Four ventures, one Erik. That is why this role exists. |