tl;dr: Y Combinator Summer 2026 demo day was thursday september 10 2026. 103 of the 234 companies in the batch were flagged on frontrun before it, with an average lead time of 51 days (median 40). 24 of them were flagged before their page existed in the YC startup directory, by an average of 47 days. every company below carries its flag date and its lead time to demo day, grouped into ten sectors.
we did the pre-directory version of this batch in august: 10 YC S26 startups that were not in the Y Combinator directory yet. this is the full picture at demo day. the fall batch is here.
the 24 that were on frontrun before the YC directory
the YC directory is published on YC's schedule, not live. a founder is accepted, moves, starts building and hiring, and the directory entry arrives weeks or months later. these 24 were flagged before their YC page existed, earliest first.
Financial Datasets (@findatasets) · the stock market as an API for agents. flagged december 27 2025, 226 days before YC listed it (page august 10)
Arbital (@arbital_xyz) · a social trading terminal for stocks, memes and perps. flagged february 5, 181 days before YC listed it (page august 5)
Wondering (@wonderingapp) · duolingo for learning anything. flagged march 11, 138 days before YC listed it (page july 27)
Vendo (@runvendo) · let your users build their own features on your product. flagged april 29, 81 days before YC listed it (page july 19)
Litmus (@uselitmus) · evals for humans. flagged may 6, 63 days before YC listed it (page july 8)
Graphify Labs (@graphify) · a knowledge graph engine for enterprise software. flagged may 26, 61 days before YC listed it (page july 26)
screenpipe (@screenpipe) · turns your screen activity into agents. flagged may 15, 53 days before YC listed it (page july 7)
Hebbian Robotics (@hbr_pbc) · data quality checks for robotics training data. flagged june 23, 45 days before YC listed it (page august 7)
Edgerun (@edgerun_inc) · military exoskeletons. flagged july 8, 44 days before YC listed it (page august 21)
Parasma (@parasmaai) · human brain cells as compute. flagged may 18, 37 days before YC listed it (page june 24)
PRINCEPS (@princepsdev) · an insurer for the compute buildout. flagged july 13, 31 days before YC listed it (page august 13)
Nebula Security (@nebusecurity) · an autonomous AI cyber defense system. flagged june 4, 28 days before YC listed it (page july 2)
Proprio Robotics (@propriorobotics) · robots that build and maintain data centers. flagged july 1, 20 days before YC listed it (page july 21)
Olam Labs (@olam_labs) · multi-agent simulations for evals and training. flagged june 30, 20 days before YC listed it (page july 20)
Buildbox (@heybuildbox) · agent analytics for real user outcomes. flagged july 9, 19 days before YC listed it (page july 28)
Stoa (@stoaexchange) · the market behind AI hardware. flagged july 13, 16 days before YC listed it (page july 29)
OneTriangle (@onetriangleai) · the cheapest, fastest inference cloud. flagged june 25, 11 days before YC listed it (page july 6)
Caution (@cautionhosting) · hosting for software you can't afford to have hacked. flagged july 23, 11 days before YC listed it (page august 3)
Nori (@norirobotics) · a humanoid robot for $1,688. flagged june 23, 10 days before YC listed it (page july 3)
Tracer (@tracerml) · combines open-source models for better answers at lower cost. flagged july 19, 10 days before YC listed it (page july 29)
Agentcard (@agentcardhq) · payment cards for AI agents. flagged may 29, 7 days before YC listed it (page june 5)
Egoist Machines (@egoistmachines) · your personal context, portable across every AI app. flagged july 16, 6 days before YC listed it (page july 22)
Conifer (@coniferbuild) · least-cost routing that cuts token spend 70%. flagged july 4, 4 days before YC listed it (page july 8)
Fabraix (@fabraixhq) · red-teaming for AI agents. flagged july 9, 4 days before YC listed it (page july 13)
all 103, by sector
lead time counts from the flag date to demo day, september 10 2026. earliest first within each sector.
1. defense, aerospace & space (5)
Edgerun (@edgerun_inc) · military exoskeletons. flagged july 8, 64 days before demo day
founder: 
David Venegas
Hop Aero (@hop_aero) · rocket cargo delivery anywhere on earth. flagged july 28, 44 days before demo day
founders: 
Matija Milenovic, Jacob Balaj
IMPACT Drones (@impactdrones) · air defense as a service for civilian infrastructure. flagged august 5, 36 days before demo day
founders: 
Jasper Lortije, Alessandro Fiume
Exosat (@exosat_) · a sovereign alternative to starlink. flagged august 7, 34 days before demo day
founder: 
Edward Ge
Ethos Space (@ethosspace) · making silicon on the moon. flagged september 3, 7 days before demo day
founders: 
Ross Centers, 
Brogan BamBrogan
2. robotics & physical ai (14)
Hebbian Robotics (@hbr_pbc) · data quality checks for robotics training data. flagged june 23, 79 days before demo day
Nori (@norirobotics) · a humanoid robot for $1,688. flagged june 23, 79 days before demo day
founder: 
Antonio Sitong Li
Most Robotic (@mostrobotic) · a research lab building the most robotic household. flagged june 30, 72 days before demo day
founders: 
Claire Mao, Lucy Cai
Proprio Robotics (@propriorobotics) · robots that build and maintain data centers. flagged july 1, 71 days before demo day
founder: 
Anirudh Pai
Mireye (@mireyehq) · a search engine for the physical world. flagged july 1, 71 days before demo day
founder: 
Ansh Chokshi
Cosmic Robotics (@cosmic_robotics) · autonomous construction on earth and beyond. flagged july 8, 64 days before demo day
founders: 
James Emerick, 
Lewis Jones
Waddle Labs (@thewaddlelabs) · LLMs that control robots. flagged july 27, 45 days before demo day
founders: 
Hanming Ye, 
Yiding Song
Salem Robotics (@salemroboticshq) · robots for hazardous spaces. flagged august 5, 36 days before demo day
founders: Caleb Horan, Janak (Crasun) Panthi
Enact (@enact_labs) · real-world RL environments for robotics models. flagged august 11, 30 days before demo day
founders: 
James Stevens, 
Govind Chada
Datoric (@datoricai) · the training data engine for physical AI. flagged august 11, 30 days before demo day
founders: Nikhil Reddy, 
Jeffrey Lin
OS3 (@os3robotics) · affordable humanoids built to deploy at scale. flagged august 12, 29 days before demo day
Shiraz AI (@shiraz_ai) · robots that learn on the job. flagged august 12, 29 days before demo day
founders: 
Navid Aghasadeghi, 
Mojtaba Mozaffar
Moving Atoms (@movingatomslab) · virtual reality for training robots. flagged august 14, 27 days before demo day
founders: 
Shehryar Saroya, Ahmad Saroya
DeepReach (@deepreach_ai) · a network for physical AI data. flagged august 16, 25 days before demo day
founder: 
Chris Liu
3. chips, hardware & compute (13)
Parasma (@parasmaai) · human brain cells as compute. flagged may 18, 115 days before demo day
founder: 
Sean Cole
ProvenMetal (@provenmetal) · AI-native electronics manufacturing for america. flagged july 13, 59 days before demo day
founders: 
Johnny Doyle, 
Will Carkner
Atomarine (@atomarine_co) · floating nuclear-powered data centers at sea. flagged july 27, 45 days before demo day
founders: 
Dimitris Koutentakis, Emile Germonpre
Synapse Semiconductor (@synapsesemi) · semiconductors that merge compute and vision. flagged july 28, 44 days before demo day
founders: Sanjeev Chauhan, Tania Roy
Applied Electrodynamics (@ae_dynamics) · a camera that sees through walls. flagged july 30, 42 days before demo day
founders: 
Bilgehan Avser, Brian Huppi, Paul Leutheuser, George McLean
Lamb Labs (@lamblabs) · chips with hardcoded AI models. flagged august 5, 36 days before demo day
founders: 
Niki Kotecha, Thomas Lanning
Standard Machines (@stanmachines) · teaching AI to design chips. flagged august 6, 35 days before demo day
founder: 
Jacob Peake
Kara (@karalabsai) · diamond semiconductors. flagged august 11, 30 days before demo day
Pacific (@pacific_ycs26) · mass-produced micro data centers. flagged august 13, 28 days before demo day
Aerogen Systems (@aerogensystems) · modernizing chip manufacturing infrastructure. flagged august 19, 22 days before demo day
founders: Noah Vogel, Colin Lavery
Daqstra (@daqstra) · AI-native test infrastructure for hardware companies. flagged august 25, 16 days before demo day
founders: 
Darell Chua, 
Anchit Kumar
hardware intelligence (@hwintelligence) · AI tools for the chips your AI runs on. flagged august 29, 12 days before demo day
founders: 
Athreya Anand, 
Rishov Sarkar
Baud (@baudlabsai) · AI chips for ultra-fast training and inference. flagged september 2, 8 days before demo day
founders: 
Sarang Zambare, Eric Taylor
4. ai infrastructure (14)
Litmus (@uselitmus) · evals for humans. flagged may 6, 127 days before demo day
founders: 
Shaivi Rau, 
Elena Zhao
OneTriangle (@onetriangleai) · the cheapest, fastest inference cloud. flagged june 25, 77 days before demo day
founders: 
Hannah Chung, 
Medha Venkatapathy
Olam Labs (@olam_labs) · multi-agent simulations for evals and training. flagged june 30, 72 days before demo day
founders: 
Om Buddhdev, 
shreshth sharma
Conifer (@coniferbuild) · least-cost routing that cuts token spend 70%. flagged july 4, 68 days before demo day
founders: 
Charles Muehlberger, 
Michael Jeffords
Touchmark (@touchmarkai) · a market for future inference capacity. flagged july 8, 64 days before demo day
founders: 
Ilia Bolgov, 
Roman Yanushevskyi
Buildbox (@heybuildbox) · agent analytics for real user outcomes. flagged july 9, 63 days before demo day
founders: 
Trishala Jain, 
Mark Nour
Petrarch (@petrarchinc) · internal industrial data for frontier labs. flagged july 13, 59 days before demo day
founders: Ian Lee, Samuel Hahn, Sudhish Swain
Tracer (@tracerml) · combines open-source models for better answers at lower cost. flagged july 19, 53 days before demo day
founder: Adam Rida
Experiential Labs (@explabsai) · an AI gateway that turns your traffic into better models. flagged july 21, 51 days before demo day
founders: 
Kion Fallah, 
Silen Naihin
hiloop (@hiloopai) · autoresearch as a service. flagged july 29, 43 days before demo day
founders: 
Karan Brar, 
Thomas Boser
CoArena (@coastyai) · the biggest crowdsourced benchmark for computer use. flagged july 29, 43 days before demo day
founders: 
Prateek Jannu, 
Nitish Kovuru
Decawork (@decawork) · company-specific models that approve AI actions. flagged august 12, 29 days before demo day
founders: 
Aman Raj, 
Sarthak Aggarwal
Speko (@speko_ai) · openrouter for voice AI. flagged august 13, 28 days before demo day
Agnost AI (@agnostai) · finds where agents fail, then trains better models. flagged september 7, 3 days before demo day
founders: 
Shubham Palriwala, 
Parth Ajmera
5. agent infra & dev tools (13)
Vendo (@runvendo) · let your users build their own features on your product. flagged april 29, 134 days before demo day
founders: 
Nour Zahzah, 
Yousef Helal
Graphify Labs (@graphify) · a knowledge graph engine for enterprise software. flagged may 26, 107 days before demo day
founder: 
Safi Shamsi
Context.dev (@getcontextdev) · realtime web context for agents. flagged june 1, 101 days before demo day
founder: 
Yahia Bakour
Pluto (@talentpluto) · linkedin for agents. flagged july 1, 71 days before demo day
founders: Sahil Seth, 
Maki Potamianos, 
Tony Xavier
Prized (@useprized) · a cloud devbox that feels local. flagged july 1, 71 days before demo day
founders: 
Hudson Griffith, Marinos Eliades
Inkbox (@inkbox_ai) · the identity and communication layer for agents. flagged july 12, 60 days before demo day
founders: 
Ray Liao, 
Dima Vremenko, 
Alex Wilcox
Hoplite (@hoplite_sh) · deploy cloud software factories. flagged july 14, 58 days before demo day
founders: 
Ryan Morrissey, 
Bence Redmond
Egoist Machines (@egoistmachines) · your personal context, portable across every AI app. flagged july 16, 56 days before demo day
founders: 
Erin McGurk, 
David Khachaturov
machine0 (@machine__0) · AWS for agents. flagged august 1, 40 days before demo day
founder: 
Barnaby Malet
GitCafe (@gitcafe) · the git forge for the next hundred billion commits. flagged august 7, 34 days before demo day
founder: Veronica C.
Agent FM (@agentfmai) · one group chat to steer your coding agents. flagged august 7, 34 days before demo day
Archal (@archal_labs) · API sandboxes built for agents. flagged august 14, 27 days before demo day
founder: 
Aidan Tiruvan
Amorphic Labs (@amorphiclabs) · openrouter for agent tools. flagged august 25, 16 days before demo day
founders: 
Dylan Kelly, Frank Li
6. applied ai & enterprise (14)
screenpipe (@screenpipe) · turns your screen activity into agents. flagged may 15, 118 days before demo day
founder: 
Louis Beaumont
Glen (@try_glen) · shared memory for every agent in your company. flagged june 11, 91 days before demo day
founder: 
Nikos Dritsakos
Assemble (@assembleagents) · autonomous IT delivery. flagged july 14, 58 days before demo day
founders: 
Aliyan Ishfaq, Shaurnav Ghosh, 
Shrish Janarthanan
Almanac (@usealmanac) · organizing company knowledge. flagged july 29, 43 days before demo day
founders: 
Rohan Sharma, 
Kushagra Chitkara, 
Divit Sheth
Marble (@joinmarble) · the autonomous back-of-house for restaurants. flagged july 29, 43 days before demo day
founders: Aakar Khanna, 
Arjun Chaliha
Zaplar (@zaplarinc) · an agentic hotel operating system. flagged august 1, 40 days before demo day
founders: 
Douglas Solberg, Axel Andersson Lingbert, Oscar Karlstromer, 
Jon Milles
Rex (@rexdotinc) · an AI-native BPO for order-to-cash. flagged august 3, 38 days before demo day
founders: 
Merlin Kafka, Lewis Blackwood
Locke (@lockeai_inc) · agentic government work. flagged august 7, 34 days before demo day
founder: 
Parth Badhwar
Maingen (@maingeninc) · simulating agents running industrial companies. flagged august 7, 34 days before demo day
founders: 
Phillip Yan, 
David Yang
Click (@useclick_ai) · research services for chatgpt and claude. flagged august 10, 31 days before demo day
founder: 
Aditya Asgaonkar
Zomma (@zommalabs) · an AI BPO for financial services. flagged august 11, 30 days before demo day
founders: 
Jihyun Kim, Varun Arumugam, Cashel Fitzgerald
RealPact (@realpact) · an AI-native OS for real estate brokerages. flagged august 18, 23 days before demo day
founders: 
Ranvir Deshmukh, Erik Peterson
OpenTag (@tryopentag) · a model-agnostic AI coworker in slack. flagged august 26, 15 days before demo day
founders: 
Tony Kam, 
Wilson Nguyen, Shelden Shi
Dock (@trydock) · a multiplayer workspace for agents and humans. flagged september 9, 1 day before demo day
founders: 
Mike Molinet, 
Govind Kavaturi
7. fintech & insurance (12)
Financial Datasets (@findatasets) · the stock market as an API for agents. flagged december 27 2025, 257 days before demo day
founder: 
Virat Singh
Arbital (@arbital_xyz) · a social trading terminal for stocks, memes and perps. flagged february 5, 217 days before demo day
founders: 
Karon Pangestu, 
Steven Mulyawan, 
Vincent Owen Toniwan
Agentcard (@agentcardhq) · payment cards for AI agents. flagged may 29, 104 days before demo day
founders: 
Karen Serfaty, 
Felipe Abello
PRINCEPS (@princepsdev) · an insurer for the compute buildout. flagged july 13, 59 days before demo day
founders: Conrad Frøyland Moe, 
Anya Trofimova
Stoa (@stoaexchange) · the market behind AI hardware. flagged july 13, 59 days before demo day
founders: 
Berat Celik, 
Eren Berke Saglam, 
Kaan Yigit
Risklytics (@risklytics) · insurance for frontier tech. flagged august 13, 28 days before demo day
founders: 
Samuel Gold, 
Alexander Risio
Definite (@usedefinite) · back-office agents on a live model of your books. flagged august 15, 26 days before demo day
founders: 
Gurshabd Singh Varaich, Mazin Al-Ani, 
Farhan Ur Rehman
LATO (@lato_ai) · predicts how market participants behave. flagged august 18, 23 days before demo day
Last Accounting Company (@lastaccounting) · an accounting firm with no accountants. flagged august 22, 19 days before demo day
Donkey (@trydonkeytrade) · an AI trading company, factory prices delivered. flagged august 23, 18 days before demo day
Pennant (@pennant_ai) · a world model for corporate governance. flagged august 25, 16 days before demo day
founders: 
Ryan Nowicki Stewart, 
Tomas Taylor
Rational (@rationaldotto) · a zero-human accounting firm. flagged september 9, 1 day before demo day
founders: 
Jibril Moinuddin, Christ Xu
8. cybersecurity (5)
Nebula Security (@nebusecurity) · an autonomous AI cyber defense system. flagged june 4, 98 days before demo day
founders: 
Eten Zou, Yuan Tan, 
Frank Wu, 
Xiaochuan Yu
Fabraix (@fabraixhq) · red-teaming for AI agents. flagged july 9, 63 days before demo day
founders: 
Ahmed Aly, Ibrahim Abdu
Caution (@cautionhosting) · hosting for software you can't afford to have hacked. flagged july 23, 49 days before demo day
founders: 
Anton Livaja, 
Ksenia Lesko, Lance Vick
Trident (@tridentsecures) · autonomous offensive security agents. flagged august 14, 27 days before demo day
Verdict Machine (@verdict_machine) · AI cybersecurity for digital-asset institutions. flagged august 18, 23 days before demo day
9. healthcare & biotech (8)
Atlas Discovery (@atlasdiscovery0) · an AI-native pharma company. flagged june 24, 78 days before demo day
founders: 
Shaamil Karim, 
Sanjukta Bhattacharya, Christian Gensbigler
Lumeria (@lumeria_skin) · oura ring for skin. flagged july 28, 44 days before demo day
Omanta (@omantahealth) · a research lab for one patient. flagged august 5, 36 days before demo day
founders: Alfredo Gonzalez, 
Ranad Humeidi
Gutgutgoose (@gutgutgoose) · sequences your gut and builds the probiotics it's missing. flagged august 6, 35 days before demo day
founders: Leon Mojarrabi, Anis Mihrshahi
TareBio (@tarebioinc) · vaccines for any cancer or infection in weeks. flagged august 6, 35 days before demo day
founder: 
Eta Atolia
Rasyn (@rasyn_lab) · making chemicals 100,000x faster. flagged august 14, 27 days before demo day
founders: 
Ansh Tiwari, Ayush Chauhan, 
Daood Hashmi
Radley (@radleyai) · an AI-native radiology practice. flagged august 19, 22 days before demo day
founders: Maryam Jahed, Seak Meng Lay
Prescience (@getprescience) · health insurance that keeps employees healthy. flagged august 19, 22 days before demo day
founders: 
Rishab Jain, 
Aditya Jain
10. consumer (5)
Wondering (@wonderingapp) · duolingo for learning anything. flagged march 11, 183 days before demo day
founders: 
Cheng-Wei Hu, 
Angelica Kosasih
Moonshot (@heymoonshot) · agents for the rest of us. flagged july 13, 59 days before demo day
Tsenta (@tsentaai) · an AI career agent that applies for you. flagged july 23, 49 days before demo day
founders: 
Agnay Srivastava, 
Pulkit Gupta
TryNearby (@trynearbycom) · local creators for local businesses. flagged august 18, 23 days before demo day
founders: 
Yousef Abdelfattah, Obaida Albaroudi, Ahmad Ibrahim
Touchy (@touchyapp) · an AI iphone assistant that sees and acts. flagged august 20, 21 days before demo day
founders: 
Rohit Agarwal, 
Andrew Liu, 
Kevin Wang
what to do with this
the list is public now. the dates are the point: every company above was on frontrun on the day shown, and a YC batch is the easiest place to check that claim because the directory and demo day are public timestamps. the fall 2026 batch is being flagged the same way, before the directory lists it.
follow from the front. frontrun.vc
open source deal flow
companies and founders surfaced on frontrun. curated, every week.
