Jon Xu @xuster
General Partner @YCombinator, Co-Founder @FutureAdvisor (YC S10), MIT EECS San Francisco, CA Joined June 2007-
Tweets336
-
Followers3K
-
Following355
-
Likes507
@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
YC startup school india avengers moment
Garry Tan @garrytan
902K 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
38K Followers 5K Following Founded and sold @Optimizely and @LimitlessAI. Created products considered impossible and made them inevitable.
Antonio García Mart�... @antoniogm
225K Followers 17K Following Director, @base growth. Founder @spindl_xyz (acq. @coinbase). Wrote bestseller 'Chaos Monkeys'. גם זה יעבור 🇺🇸🇪🇸
Jerry Lin @jerrylin
767 Followers 802 Following Formerly engineering at @square. Still no dietary restrictions.
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 364 Following We help founders make something people want. Subscribe to our newsletter: https://t.co/sjqjxxBeLc
Jentroy @jentroyug
199 Followers 2K Following Technology that scales organizations. Odoo Partner | ERP, custom software, systems integration & AI 📩 [email protected]
Shitiz Aggarwal @Shitiz_Agg
732 Followers 523 Following Senior Product Designer | I design 0→1 products for startups | Winner SIH'22, Tezasia’22 | @Travelswap @coin_voyage @dyorcryptoapp @nf3exchange
Mark Francis @ejmfrancis
568 Followers 6K Following Founder & Director of @preferrdrecruit | @eurasiansociety | https://t.co/MxQaRAsNXD | https://t.co/55MHtMSAdY and https://t.co/0SwZmb0NT3 - I like to keep busy!
Trent 📈 @trenz999
6K Followers 5K Following Software engineer || PMM || Early-stage scout helping VCs and accelerators identify breakout founders and connect them to global capital .
cty @cty
52 Followers 1K Following
Venture Launch @venture_launch
7K Followers 705 Following We design and run acceleration programs, education tracks, and pop-up cities for emerging ecosystems
Ahd Ben kheder @ahd_bk
208 Followers 1K Following Technology lover 🚀 Microsoft Certified Professional😎 Blog @supersharpdev
Mpilwenhle Sithole @mpilwenhle70769
4 Followers 146 Following
Chris Halaska @chalaska
15K Followers 3K Following Product Designer, ex. @Google Founder @Halaska | @DashByHalaska
Ashton Nath @Asht0nNath
158 Followers 256 Following Cofounder @getcoconutapp + building Bulletin | Sharing progress | Information Systems + Entrepreneurship @UFWarrington | authentically me
Mohak @mohakbatra2001
3 Followers 254 Following
EJ Zhangs⚡️ @EJZhang_TUKEY
330 Followers 124 Following We build creative intelligence for content creators. @TukeyAI
Susanna Pullen @svpullen
36 Followers 310 Following
Masoud Ghanbari @masoudghanbari_
5 Followers 140 Following Data architect || https://t.co/2HRXiBpSix
re-a g1359402 @re_a_takaki
290 Followers 2K Following 元陸上自衛官→AI起業家|安全第一の自律型AIエージェント「理愛/Riai」開発中|AI×自律化で「安全・時間・所得」の余白を増やす|UX設計/開発ログ|UGW代表
Rebirthless @rebirthless
40 Followers 587 Following
Adrian Schepelern @Floppydisk100
4 Followers 128 Following
Lucas Kunzelmann @KunzelmannLucas
3 Followers 96 Following
Logesh Ramesh @LogeshR_2005
1 Followers 60 Following Backend Eng (Java/Spring Boot). Built a data population system @Zoho generating 30M+ rows for QA/support teams.
Aurideep Nayak @AuriNayak
11 Followers 10 Following
Rami Janini @ramijanini1
1 Followers 140 Following
Umar Ghani @UmarGhani_
15 Followers 56 Following 19 | engineering @qualcomm | @ucberkeley | building
Mohammadreza Zare @MRezaZare_
117 Followers 4K Following Explorer & Builder | Medical Student @ TUMS | Focused on Clear Thinking, Problem Solving & Impact
Dhruv Mathur @dhruvtoocool
5 Followers 76 Following
Tara Roskell - Abstra... @tararoskellart
3K Followers 3K Following Artist creating abstract faces and loose abstract city scenes
Mohammed Shahir.p @sh58996
2 Followers 51 Following
Vivek Dagur @Vivek_Dagur27
1 Followers 223 Following
Scott Barrington @SDBarrington
409 Followers 2K Following Co-Founder at Harth (backed by BlackBird, SideStage & IceHouse) https://t.co/r6BAz3m8ft
Faiz Raza @FaizShahnawaz1
10 Followers 84 Following I help Pre-Seed, Seed, & Series A startup founders turn their ideas into scalable products.
Kofi S. Boahen (The T... @DaTradeKing
186 Followers 623 Following Building Africa’s B2B Wholesale Marketplace | Co-founder / CEO @AfricanExporter
Amy Jain @notamyjain
665 Followers 878 Following know everything (prev. @jpmorgan @pearvc @ucberkeley)
Paul Graham @paulg
3.6M Followers 795 Following
Garry Tan @garrytan
902K 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 655 Following Dad, husband, brother, son, friend, founder, investor (@Supabase, @WeAreLegora, @DecagonAI,+++). MD @GeneralCatalyst. Previously @WayfinderVC @YCombinator.
Alexandr Wang @alexandr_wang
514K Followers 858 Following chief ai officer @meta, founder @scale_ai. rational in the fullness of time
Antonio García Mart�... @antoniogm
225K Followers 17K Following Director, @base growth. Founder @spindl_xyz (acq. @coinbase). Wrote bestseller 'Chaos Monkeys'. גם זה יעבור 🇺🇸🇪🇸
Jerry Lin @jerrylin
767 Followers 802 Following Formerly engineering at @square. Still no dietary restrictions.
Harry Stebbings @HarryStebbings
488K Followers 376 Following 🎤 @twentyminutevc, 🏦 @20vcfund, @projecteurope_😇 @fuseenergy @linear @wearelegora @factoryai @lovable @airwallex @mercor_ai @workos
Patrick OShaughnessy @patrick_oshag
341K 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
281K Followers 946 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 364 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
Yahia Bakour @mynameisyahia
6K Followers 2K Following @getcontextdev (YC S26) - One API to scrape, enrich, and understand the web
conor brennan-burke @contextconor
9K Followers 3K Following the company brain guy. founder @hyperspell (yc f25)
Andrew Miklas @amiklas
2K Followers 78 Following
Finbarr Taylor @finbarr
6K Followers 874 Following Visiting Partner @ycombinator. Founder & former CTO & CEO @Shogun. Angel investor in 60+ companies. Startups, the universe and everything. 🏴
Abhishek Sharma @oneabhishek
4K Followers 763 Following Tech & AI investing @NexusVP • 💙 Distribution, PLG, OSS
Philip Johnston @PhilipJohnston
26K Followers 794 Following Co-founder & CEO of @Starcloud_ - Building data centers in space.
Mathilde Collin @collinmathilde
24K Followers 1K Following Co-founder & Exec Chair at @FrontHQ. Angel investing. KORA.
Tom Blomfield @t_blom
79K Followers 929 Following Partner at @ycombinator Cofounded @gocardless and @monzo
Sam siavoshian @samsiavoshian
474 Followers 1K Following GTM eng @ReacherApp YC (S25) | 6x hackathon winner | Founder of @ArenaAiApp | Yes, I'm still in high school
Manufact @manufact
958 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
Vivian Midha Shen @vivianmshen
28K Followers 777 Following visiting partner @ycombinator. planning in centuries @amppublic.
max @maxkolysh
3K Followers 456 Following visiting partner @ycombinator || founder at @doverhq @zincdotcom
eve @eve_bouff
3K Followers 657 Following 𝚑𝚎𝚊𝚍 𝚘𝚏 𝚍𝚎𝚜𝚒𝚐𝚗 (𝚌𝚑𝚒𝚎𝚏 𝚏𝚞𝚗 𝚘𝚏𝚏𝚒𝚌𝚎𝚛) @ycombinator ~ 𝚠𝚎𝚕𝚌𝚘𝚖𝚎 𝚝𝚘 𝚖𝚢 𝚜𝚝𝚛𝚎𝚊𝚖 𝚘𝚏 𝚌𝚘𝚗𝚜𝚌𝚒𝚘𝚞𝚜𝚗𝚎𝚜𝚜
Brontë Kolar @BronteKolar
469 Followers 385 Following cofounder @zeonsystems // making robots do science
Ryanair @Ryanair
926K Followers 58 Following Catch flights, not feelings with Europe’s no. 1 airline 💅
Jerry Wu @Jerr_Wu
362 Followers 878 Following RL environments for knowledge work Founder @ https://t.co/tzjRHkYIfF CS/ML @cornell.
Grey Baker @greybaker
3K Followers 256 Following Partner at @ycombinator. Co-founded @pincitesai (acq. by @filevine) and @dependabot (acq. by @github), and was employee #3 at @gocardless.
Aakash Gupta @aakashgupta
279K Followers 832 Following ✍️ https://t.co/8fvSCtBv5Q 💼 https://t.co/STzr4nqxnm 🤝 https://t.co/SqC3jTyP03 🎙️ https://t.co/fmB6Zf5UZv
GLADIA Research Lab @GladiaLab
5K Followers 25 Following Based in Rome, GLADIA is a team of computer scientists, physicists, engineers and mathematicians venturing beyond the boundaries of machine intelligence
Hubert Thieblot @hthieblot
59K Followers 3K Following Investing @fdotinc, Founder @curseforge acq by @Twitch, love @oheather1337, 3x dad, 🇫🇷🇨🇭🇺🇸
Omar Khattab @lateinteraction
36K Followers 3K Following asst professor @MIT CSAIL @nlp_mit. https://t.co/VgyLxl0VZz, https://t.co/ZZaSzaRIOF (@DSPyOSS), GEPA, RLMs, Pedagogical RL
Arnav Sahu @arnavsahu341
6K Followers 867 Following Partner @peakxvpartners (fka Sequoia India) in Bay Area. Ex-@ycombinator, @sparkcapital, @appdynamics, @blackstone @wolfia_app. Underdog. I love 🫡 emoji.
Arlan @arlanr
22K Followers 3K Following 19, ceo @nozomioai (yc s25) | kicked out from high school, stanford research at 16
Ashley @ashlleymo
256 Followers 138 Following co-founder @liva_ai (yc s25) | prev cs @caltech | sometimes i dance
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
15K Followers 463 Following Partner @ycombinator. Co-founder of AtoB (https://t.co/K4GSvO9VhC).
Supabase @supabase
202K Followers 99 Following The Postgres development platform. 🌐 https://t.co/kHsst88XA1 ⭐️ https://t.co/txGagqok1i 🎥 https://t.co/6eTjCTIrzK 💬 https://t.co/ikFm89oPVI
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
20K Followers 113 Following Founder @origamichat -helping you get customers. Studied ai @stanford
Shengjia Zhao @shengjia_zhao
52K Followers 235 Following Chief Scientist @ Meta MSL. Formerly MTS @ OpenAI, PhD @ Stanford. I train models. All opinions my own.
Prem Qu Nair @premqnair
6K Followers 1K Following @cognition/@windsurf, previously @nuro @princeton. Pursuing 70mm, 225lb, and $0.10/piece
Alda Leu Dennis @AldaLeuDennis
2K Followers 269 Following investing @Hawktail Board Partner @Initialized
René Brandel @renebrandel
2K Followers 1K Following building @getcasco (YC X25) | invented @kirodotdev, ex-@awscloud, ex-@microsoft, ex-@skype
Charlene Wang @hsinleiwang
1K Followers 667 Following CEO & Co-Founder, @EmberCopilotAI. Formerly, @Google Health.
Kim-Mai Cutler @kimmaicutler
58K Followers 32K Following Partner at @initialized. When life hands me lemons, I make tarte au citron.
Arfur Rock @ArfurRock
40K Followers 5K Following anon GP at your favorite multi-stage VC // OS intel for the private markets

































