Pete Koomen
General Partner, Y Combinator · 8 appearances on the record.
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founderinvestorexecutiveauthor@koomen ↗LinkedIn ↗ycombinator.com/people/pete-koomen ↗
He co-founded the experimentation and A/B testing platform Optimizely, serving as CTO prior to its acquisition by Episerver. As a General Partner at Y Combinator, he advises early-stage founders, spearheads internal AI agent infrastructure, and co-authored the book A/B Testing.
51statements → 12claims → 4claims resolved → 75%fully supported → 3.8/5average certainty → 1.88/5average debate potential → 3said about them ↓
3 supported 0 partly supported 1 contradicted 8 not checkable as stated how the 12 claims stand · each chip opens the sources
4 predictions · 8 assertions · 5 opinions · 26 insights · 8 disclosures · every statement was checked. The predictions and assertions are the 12 claims: statements the public record can support or contradict. 4 are resolved, and 8 name no date, number or outcome precise enough to check. Everything else (opinions, insights, what ifs, disclosures) can never be settled by the record, so it carries no assessment.
The record, in short
What the tape says about how Pete argues and how the claims held up. Everything they said, and everything said about them, is in the tabs below.
Their most notable supported claim
Non-legal founders built Vessence MVP by embedding inside a law firm
“I worked with a company in the previous batch, the Spring batch, which was just now wrapping up, called Vessence, that are building software for lawyers. And neither of the founders has a legal background, and so the way that they got started before YC was the…”
Their most notable contradicted claim
Koomen: Optimizely started as manual A/B testing consulting before building software
“We actually had this example at Optimizely where we were building software to help companies run A-B tests. But at the earliest stages, we got companies to pay us just to go in and manually build A-B tests. For them. Right. And so we're making money. The first…”
Expressed certainty vs assessment result
weighted support: a fully supported claim counts one, a partly supported claim counts half. Each filled bar is clickable and opens exactly those claims; "none yet" means nothing said at that certainty level has resolved yet
How they sound: not measured why? →
We measure speaking style by listening to the audio itself, and a fair number needs at least 2,000 words from one person on tape we have measured. There is too little of Pete Koomen on measured tape to publish a rate. This says nothing about how they speak.
Everything Pete Koomen said on the Y Combinator Startup Podcast that made the record, most notable first. Filter by type, assessment or year in the ledger →
Koomen: AI-native software will be agents wrapping tools, not apps wrapping AI
“I think the conclusion that this essay points to is that as we get better at building AI native software. It's going to look a lot more like the agent wrapping software deterministic tools rather than deterministic software wrapping an AI.”
Koomen: Developer AI tools lead by avoiding defensive corporate restrictions
“Developer tools are power tools, right? Developer tools by definition allow you to get to the bare metal, right? To get under the hood of what it, whatever it is you're working with. And so the teams that built these tools allowed me Full access to have this a…”
Koomen: Quoting Too High Rarely Scares Off Genuinely Interested Customers
“One of the most surprising things I learned was that when a customer really wants your product, it's hard to scare them away by quoting a price that's too high.”
Koomen: Centralized databases enable AI agents to answer arbitrary business questions
“When all of that context is in one place, with a little bit of additional information about how the schema is laid out. An agent can go and ask any, or answer arbitrary questions about our business.”
Koomen: YC runs a nightly AI agent to review employee interactions
“We have this general agent that every night will go, And read through all of the agent conversations that employees have had, and look for things that could have done better, and pieces of context that if it had, up front, it would have done more efficiently.”
Early startup hiring slows founders down instead of speeding them up
“When I have founders that are working in the batch who ask if they should hire almost always the answer is no, right? Founders will make the mistake of thinking it will speed them up, but in reality it ends up doing the opposite.”
Koomen: Gemini is incredible, but Gmail's UI makes it frustrating to use
“Gemini is amazing. The model itself is absolutely incredible. We've been using it a lot at YC to automate our own work. I'm so impressed with what they built. But a lot of that power I think is hidden behind a UI that makes it really frustrating to use.”
Koomen: Legacy software mindsets prevent unlocking AI's full potential
“Part of the problem is that We're using old software development mentality, old software development techniques to build these features, and we're not actually taking full advantage of what AI can do.”
Koomen: AI developers mistakenly treat system prompts like legacy code
“My contention is that A lot of AI app developers, including the Gmail team in this case, are treating the system prompt the same way they've been treating code for decades.”
Koomen: Every profession will have its Cursor or Windsurf moment
“It's basically every profession I think will have its cursor moment or its windsurf moment.”
Koomen: Mainstream users will adopt AI prompting faster than personal computing
“And I think the same thing is going to happen with prompting. So I think this is actually going to happen a lot faster with prompting, because writing a prompt is a lot more accessible than, you know, operating your file system manager on, on your computer. Yo…”
Koomen: Writing prompts will become part of daily workflow for many
“Some of the work that we've done at YC, building agents to automate some of the repetitive work that we and our teammates do on a regular basis, actually suggests to me that writing prompts is going to be part of the day-to-day flow for a lot of people.”
Koomen: Moving Startups Post-YC to Cheaper Cities Is a Mistake
“I'll give one example of a mistake that I see founders making today, where I think they're being penny wise and found foolish, is moving their startup after YC to a city where it's much cheaper to live and much cheaper to hire.”
Koomen: Nobody has solved multiplayer organizational AI agent harnesses yet
“I think one of the big problems that I don't think has been solved well yet by anybody is the multiplayer harness, right? It's enabling that kind of superpower, but on a team or an organizational level.”
Koomen: YC improved AI pitch skills using office hour transcripts
“One of the cool things that happened in the last month or two was that a couple of the other partners took a meeting that they had with a group office hours they had with a bunch of the companies in the spring batch and just went through and had every founder …”
Koomen: Future software will be minimal code letting AI models shine
“The best AI software that I've used, whether it's inside of YC or tools that others have built, tend to be very small, and just add kind of the smallest amount of code ahead of time that you need in order to let the model shine. And you can build an awful lot …”
Koomen: Commercial software will soon ship with self-extending AI capabilities
“I suspect that a lot of commercial software will come with this capability out of the box in the future.”
AI SDRs cannot rescue startup founders who are unable to sell
“AI SDRs tend to work well when they're plugged into a sales process that's already working well, and where I haven't seen them work well is when founders sort of turn to an AI SDR as the solution of last resort, where they're just totally unable to sell their …”
Losing conviction is the leading indicator that a founder should pivot
“The actual leading indicator that maybe you should pivot is you just stop believing that what you're working on is going to work out.”
Koomen: Cursor and Windsurf are the most powerful software tools ever used
“When I use tools like Cursor and Windsurf to build software with AI, it feels like the most powerful tool I've ever used, right? It's this feeling of being able to create anything I want, anything I can picture in my head you know, will materialize in front of…”
Pete Koomen: Gmail's AI drafter sounds unnatural and saves no effort
“There's two big problems with this. The first problem is like you're pointing out that doesn't sound anything like me, right? If you got this email, you wouldn't, you would assume somebody else wrote this. My account got hacked. I got phished. And then the sec…”
Koomen: AI models can handle complex, multi-step scheduling workflows
“These AI models are now capable of doing things like that, where it's actually anticipating all of the things that will need to happen as a result of my daughter waking up with the flu and helping me do those things.”
Koomen: Editable system prompts remove repetitive prompting for AI
“By editing this system prompt, I'm able to explain to the AI model how I write emails in general, so that I don't have to do it every single time.”
Koomen: LLMs are like smart fresh grads needing specific instructions
“The way that I think of these models, a super smart, you know, fresh grad right out of college that can do anything pretty well, but it has no idea what to do, you know, and the missing step is giving me the ability to teach it how to do work that I don't want…”
The other half of the tape: Pete Koomen's own voice is left out of every number here. Other people bring the name up 3 times in 2 episodes on the Y Combinator Startup Podcast. every mention, with the transcript →
Who brings them up most Garry Tan 2Diana Hu 1
Every mention by year
tap a year for its mentions
2026 2 mentions in 1 episode
2023 1 mention in 1 episode
Appearances (8)
| Episode | Date | Speaking time |
|---|---|---|
| Inside YC's AI Playbook · Y Combinator | May 27, 2026 | 17m |
| Startup Advice: AI GTM, Pivoting & How To Hire · Y Combinator | Oct 21, 2025 | 3m |
| How To Design Better AI Apps · Y Combinator | May 23, 2025 | 19m |
| The Right (And Wrong) Way To Spend Money At Your Startup · Y Combinator | Feb 12, 2025 | 2m |
| How Do Billion Dollar Startups Start? · Y Combinator | Oct 11, 2024 | 15s |
| Why Startup Founders Should Launch Companies Sooner Than They Think · Y Combinator | Jul 12, 2024 | 1m |
| Enterprise Sales | Startup School · Y Combinator | Jul 8, 2024 | 20m |
| Startup Experts Discuss Doing Things That Don't Scale · Y Combinator | May 30, 2024 | 1m |