Jon Xu @xuster
General Partner @YCombinator, Co-Founder @FutureAdvisor (YC S10), MIT EECS San Francisco, CA Joined June 2007-
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YC has temporarily lost Tom to a startup with unusually high compute costs
Personal update: I'm taking a leave of absence from YC to join Anthropic. I'll be working with @NotTomBrown on the compute team. Powerful AI has the potential to improve the life of every human on earth and, as we enter the early stages of recursive self-improvement,
@sabir_huss50540 Often, a good test of conviction is if your current solution fails, are you still excited to spend time with your customers going deeper on the problem.
Founders spend too much time optimizing for the perfect startup idea. Yet most startups suffer from shallow conviction, not bad ideas. The best founders I know pick an idea they’re genuinely curious about, then burn the other boats. Here’s a simple rubric for how to do it well.
Many founders get stuck trying to find the perfect startup idea before they commit. But the perfect idea doesn't exist in the abstract. The only way to find what works is to pick one, go deep, and get feedback from real customers. In this episode of Startup School, YC's @xuster
Your startup's growth rate is also its learning rate. Setting an ambitious growth goal and trying to hit it is the fastest way to find out what's broken and how to fix it. Not just the obvious stuff. Wrong customer, wrong problem, product nobody wants. It also stresses the founding team. You find out fast whether you can handle hard problems under pressure. Bottlenecks only show up when you push. If you're not having uncomfortable discoveries early, you're not pushing hard enough.
@charliermarsh Sometimes they're a good reason to work on something. When people say a market is "crowded," what that often means is that there's a real problem and none of the solutions are good enough yet.
Founders often ask me what to listen for in customer calls to know if they have a hair-on-fire problem. This is the wrong question. Can you run their business? If you were CEO, would this be a top 2 priority? Because most businesses never get to #3. Rather than pitching your idea, learn the business so well you could run it yourself. You'll know exactly how big the problem is and what they'd pay. And if this is going to 100x their business and they still won't buy? You just discovered the AI version of their company.
A mic drop moment @ycombinator tonight @sama just offered $2M in OpenAI tokens to EVERY YC startup in the current batch in exchange for equity Just like Yuri Milner offering to invest in every startup back when Sam was a YC partner I can't wait to see what's unlocked when you let the most driven, creative and formidable founders tokenmaxx
The YC application deadline is today. If you're working with AI to close the scientific discovery loop, drop an application and tell us about it.
We’re bringing Jensen Huang to Startup School for a fireside chat with @garrytan! From co-founding @nvidia in 1993 to building the backbone of the AI era, Jensen helped turn GPUs into the engine of modern computing. Apply to attend: events.ycombinator.com/startup-school…
This summer we're launching YC Paper Club to bring researchers & builders together. Every few weeks we'll host a small group dinner in Mountain View to share and discuss new research papers. Interested in both research & building the future? Sign up at: events.ycombinator.com/ycpaperclub
MIT student asked a question earlier today that a lot of young founders are quietly wondering about: "Won’t the frontier labs just do everything?" Yes it's true that OAI/Ant are shipping at incredible pace, but it's quite easy to avoid their blast radius and build amazing startups: OpenAI is not going to build a cattle-herding drone, buy an old F-150 and drive from ranch to ranch like the founder of one of the fastest-growing YC W26 startups, Graze Mate. Anthropic is not going to integrate with dental insurance verification systems (Lance). Google is not going to navigate NATO procurement (Milliray). The value is in the last mile, not the model. Sales cycles require humans who understand the customer. And most importantly, the market is expanding, not shrinking: AI isn't cannibalizing the existing 1% software spend — it's unlocking the other 5-6% that was going to humans. That's a much bigger market for startups yet-to-be-founded than the one the labs are playing in. Now, what DOES seem risky? A thin UI layer on top of ChatGPT with no domain expertise; a general-purpose chatbot or assistant; or a product that gets obsolete when model capabilities improve. But — tools for specific industries; "full-stack" AI companies that actually are the service (AI law firm, AI accounting firm, AI uranium exploration company); or generally products where the customer doesn't want a tool but an outcome — are defensible ideas for startups.
Grateful to have @demishassabis and @GoogleDeepMind stop by YC today and hang with founders!
Congrats to @astorinvest on their $5M seed! They're building an AI investment advisor for everyday investors. It connects to your brokerage, analyzes your portfolio, and delivers personalized recommendations. Less than two months after launch, thousands of users have already connected over $200M in assets to the platform. fortune.com/2026/04/23/jjj…
AI isn't just making teams more productive. It's changing how companies should be built. In this episode of Startup School, YC Partner @sdianahu explains what it means to build an AI-native company, where AI isn't just a tool but the operating system your company runs on. She breaks down how to make your company queryable so agents can improve across every function, why management hierarchies break down when an intelligence layer replaces human middleware, and why early-stage founders have a massive edge in building this way from day one. 00:58 - AI as your company’s operating system 01:57 - Open vs closed loop companies 03:00 - Making your company fully queryable 05:00 - The rise of the 1,000x engineer 07:12 - Why middle management disappears 09:12 - Startups will win this shift
Everyone thinks about money differently. The last generation of personal investment software was fine but not truly optimal for anyone. I know because I built one. AI unlocks a truly personalized advisor with deep understanding of financial situations and personal opinions. Excited that @brunokoba_ and @tulha_ are building this at @astorinvest. Congrats guys!
We (@astorinvest) raised a $5M seed led by Monashees, with participation from Goodwater, Gilgamesh Ventures, and other incredible investors. In less than two months after launch, thousands of users have connected over $200M in assets to our platform. We're just getting started.
The team at @10x_Science is delivering a huge unlock for drug development by increasing the speed of protein characterization by orders of magnitude. David, Andrew and Vishnu are an insanely talented team working on a huge problem! And they’re hiring.
Congrats to @10x_Science on their $4.8M seed! They're building AI for molecular-level protein characterization, a process that today requires specialized scientists spending weeks or months manually interpreting complex data. Their platform delivers the same insights in minutes.
That’s a wrap on YC Startup School India. Bengaluru, you really brought it. We can’t wait to see what you’re going to build.
@_groww is now a public company and is the largest investment platform in India. @lkeshre the founder and CEO is still the power user of the product he’s built and still talks to users today. Had the privilege of sharing the stage at Startup School India where he spoke about building a generational consumer company. We talked about product taste as being not just what looks good, but intentional design choices informed by an obsession with the customer. Lalit and how the team at Groww builds products exemplify this. Photo credit: @gcs319
Garry Tan @garrytan
959K Followers 6K Following President & CEO @ycombinator —Founder @garryslist—Creator of GStack & GBrain—designer/engineer who helps founders—SF Dem accelerating the boom loop
Dan Siroker @dsiroker
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Antonio García Mart�... @antoniogm
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Jerry Lin @jerrylin
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Sachin Agarwal @agarwal
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Y Combinator @ycombinator
1.6M Followers 365 Following We help founders make something people want. Subscribe to our newsletter: https://t.co/sjqjxxBeLc
jason v02 @teamv02_com
7 Followers 182 Following I'm Jason. New account. Made by a human. Posts by a human. Building and launching apps. Out now: GPX Life (see link)
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Kaito | 海斗 @_kaitodev
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Roman Baptiste @romanbap5
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Giles-Evan Mboumi @gilesmboumi
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Alice | TikTok Shop V... @tutu_massurge
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Aditya Mittal @adityamit07
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Aarib Huq @AaribHuq
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Graft @graft_ai
4 Followers 58 Following Enabling companies to adopt AI & scale. Graft attaches a new, agent-ready interface to exisiting software without rebuilding the underlying application
josh @joshuajerinn
499 Followers 863 Following just a pebble in the universe | prev @fdotinc @cerebral_valley @tembo
Matt @meszmatew
163 Followers 627 Following Open source | Made https://t.co/JRmjhqXDzV and https://t.co/ga9cNamPOr | Creator of rebound ae plugin
Abaas Hamdani @Abaas_the_aiboy
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Sabuuuuu @Sabuuuuu69
79 Followers 1K Following 好きなものを好きなだけ浴びたい/AI agent実験中/最新のAIを試すのが好き/GASやマクロの自動化も好き
tms @AlsalemTariq
124 Followers 5K Following
Marcel Hofer @3DOfficeAT
18 Followers 99 Following 3D design, printing, and AI workflow engineering — building practical systems that engineer problems away.
Carnell Greenfield @ReservedR389
1 Followers 17 Following
Scriz @ScrizBuilds
36 Followers 216 Following Building startups with AI until one works posting the wins, failures & everything between Northeastern & Georgetown
Prashant Adsul-Ozonex... @Ozonexblue_DEF
3 Followers 78 Following Co-Founder & Director @ OzonexBlue | Building DEF (AUS32), DI/DM Water & Industrial Fluid Solutions | Manufacturing | Clean Mobility | Startup India Recognized
Geetansh Agrawal @geetansh810
19 Followers 90 Following
Kautilya Veer @KautilyaVe36127
0 Followers 25 Following Tinkerer Building CiviSight https://t.co/LRkOpdiNIj
GutGutGoose (YC S26) @Gutgutgoose
68 Followers 18 Following Personalised probiotics for your gut. 77% of Your Probiotics Die. We Know Why. 🪿Waitlist Here 👉
Aniket Raj @aniketraj08309
97 Followers 846 Following Creating Content Sometimes 🎬 | Editing Creative Cuts Into Videos 🎥| Building Thrive Store - A web3 Thrifting Store 🚀
MORYASSHAN @MORYASSHAN
0 Followers 106 Following
Nuraziz Ungboyev @nurazizdev
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Rana @roy_rudradev
57 Followers 2K Following
Durdona @durdonaakh
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Yuti G, EA @YutiG_EA
9 Followers 1K Following EA helping US founders & individuals navigate tax & compliance without overpaying | 1040 · 1040NR · 1065 · 1120 · 1120-S · Multi-State | AfterNative
Jose Zanabria Gutiér... @JoseZanabr86142
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Luis E. De Pombo @luisdepombo
161 Followers 749 Following Building @NASA SPLASH, Prev: RLHF @scale_ai, Tech governance for LatAm, BSc+MSc CEE @uofigrainger
Paarth Saxena @SaxenaPaarth_19
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SpaceSauce @SpaceSaucy
62 Followers 1K Following
Priyanshu Gupta @I_PriyanshuG
36 Followers 205 Following Content @LaunchX | Founder @BuilderFellows | Building the Builders, One Fellow at a Time. | 2x acquired founder
Ankit @ankithrc23
2 Followers 13 Following Finance × Startups × Technology Building skills one project at a time
Rashid Iqbal @rashidrealme
88 Followers 138 Following If you choose the cheapest way to build your website, you are not saving money. You are just deciding when you will pay for it again.
Marcus @marcuuuussssss
17 Followers 276 Following
Vedant Sharma @VedantS91771505
8 Followers 611 Following
Ojas Kandhare @ojaskandy
444 Followers 833 Following 19 • yc s26 • goof/ner i build ai agents that do hedge-fund level research for you. i also give Fable and GPT 5.6 money to trade
Hamza K. @Hamza_Karmouche
68 Followers 409 Following Quant @ETH — Tweeting about tech, finance & cinema. Straight outta Casablanca 🇲🇦
Sachin Manjalekar @sachinmanjaleka
415 Followers 6K Following Marketing Leader driving brand & growth Thoughts on Marketing, AI, Growth & Business. Chelsea FC & RCB since 2008
Vedant Mishra @vedantyam
41 Followers 719 Following Founder's Office @FLABS - building LIS infra for Indian path labs | prev: ran a software agency | interested in healthtech
Ashish Nasa @Ashishnasa7
751 Followers 7K Following Product Design | Prev: @ACKOIndia , @OrangeHealth , @YuluBike , @HackerEarth | IIT Roorkee | UDR | BLR
Paul Graham @paulg
4.1M Followers 793 Following
Garry Tan @garrytan
959K Followers 6K Following President & CEO @ycombinator —Founder @garryslist—Creator of GStack & GBrain—designer/engineer who helps founders—SF Dem accelerating the boom loop
Yuri Sagalov @yuris
28K Followers 661 Following Dad, husband, brother, son, friend, founder, investor (@Supabase, @WeAreLegora, @DecagonAI,+++). MD @GeneralCatalyst. Previously @WayfinderVC @YCombinator.
Alexandr Wang @alexandr_wang
559K Followers 864 Following chief ai officer @meta, founder meta superintelligence labs, founder @scale_ai. rational in the fullness of time
Antonio García Mart�... @antoniogm
226K Followers 17K Following Director, @base growth. Founder @spindl_xyz (acq. @coinbase). Wrote bestseller 'Chaos Monkeys'. גם זה יעבור 🇺🇸🇪🇸
Jerry Lin @jerrylin
766 Followers 801 Following Formerly engineering at @square. Still no dietary restrictions.
Harry Stebbings @HarryStebbings
541K Followers 378 Following 🎤 @twentyminutevc, 🏦 @20vcfund, @projecteurope_😇 @fuseenergy @linear @wearelegora @factoryai @lovable @airwallex @mercor_ai @workos
Patrick OShaughnessy @patrick_oshag
344K Followers 2K Following building @psumvc @colossusmag hosting @investlikebest
Benjamin Ling @bling0
21K Followers 1K Following Founder and GP at @blingcapital, GP @khoslaventures, Fitness junkie, formerly @YouTube @Google @Facebook
delian @zebulgar
291K Followers 947 Following space drugs and arms @vardaspace | village idiot/partner @foundersfund | porthos @hillvalleyforum
Sachin Agarwal @agarwal
33K Followers 3K Following I ❤️ San Francisco. Co-founder @GrowSF. We’re helping get SF back on track by electing leaders who focus on outcomes. We’re the #1 voter guide in SF.
Y Combinator @ycombinator
1.6M Followers 365 Following We help founders make something people want. Subscribe to our newsletter: https://t.co/sjqjxxBeLc
Rohit Mittal @rohitdotmittal
24K Followers 1K Following Buying VC-backed companies at Helium Ventures. Founder helper. Prev @stilt_inc (acq by JGW). YC W16.
Nicolas Dessaigne @dessaigne
14K Followers 297 Following Co-founder of @algolia - Group partner at @ycombinator
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Andrew Miklas @amiklas
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Finbarr Taylor @finbarr
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Philip Johnston @PhilipJohnston
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Mathilde Collin @collinmathilde
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Sam siavoshian @samsiavoshian
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Manufact @manufact
990 Followers 54 Following Helping dev teams build and deploy MCP servers / ChatGPT Apps / Claude connectors mcp-use is building open-source dev tools and infra for MCP - @ycombinator S25
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29K Followers 827 Following visiting partner @ycombinator. planning in centuries @amppublic.
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3K Followers 464 Following visiting partner @ycombinator || founder at @doverhq @zincdotcom
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Ryanair @Ryanair
930K Followers 58 Following Catch flights, not feelings with Europe’s no. 1 airline 💅
Jerry Wu @Jerr_Wu
405 Followers 879 Following RL environments for knowledge work Founder @ https://t.co/tzjRHkYIfF CS/ML @cornell.
Grey Baker @greybaker
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Aakash Gupta @aakashgupta
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Hubert Thieblot @hthieblot
59K Followers 3K Following Investing @fdotinc, Founder @curseforge acq by @Twitch, love @oheather1337, 3x dad, 🇫🇷🇨🇭🇺🇸
Omar Khattab @lateinteraction
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Arlan @arlanr
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Ashley @ashlleymo
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Raphael Schaad @raphaelschaad
28K Followers 1K Following Visiting Partner @ycombinator, helping founders build iconic startups. Swiss designer, MIT engineer, founder Cron (acq by Notion). I run through forests.
Harshita Arora @aroraharshita33
16K Followers 469 Following Partner @ycombinator. Co-founder of AtoB (https://t.co/K4GSvO9VhC).
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Lewis 🇺🇸 @ctjlewis
46K Followers 21K Following Startup counterculture. LLMs. If you think I might be able to help you with something, ask.
Finn Mallery @fin465
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