Fifty-eight AI startups from Y Combinator’s Winter 2025 (W25) and Summer 2025 (S25) batches announced an outside funding round between January 2025 and October 2026. Together they raised $586.8M across 64 rounds. Those 58 companies are about 18% of the 331 in the two batches. YC’s own $500K standard deal, which every accepted company gets, is not counted.
The money is not spread evenly. Harper, an insurance brokerage run on AI, leads with $47M. Wafer, an S25 company that speeds up AI inference, closed a $40M Series A a year after demo day. And six companies that sell training data and model evaluations to AI labs raised $112.9M between them, second only to developer tools.
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How AI-heavy were W25 and S25?
At least 136 of the 165 companies in W25 (82%) and 150 of the 166 in S25 (90%) describe an AI product.
| YC W25 | YC S25 | |
|---|---|---|
| Companies in the batch | 165 | 166 |
| Describe an AI product (at least) | 136 (82%) | 150 (90%) |
| Demo day | March 2025 | September 2025 |
| AI startups with an announced outside round | 32 | 26 |
| Outside funding to those AI startups | $335.7M | $251.1M |
| AI startups that reached Series A | 7 | 3 |
| All companies marked acquired by YC | 4 | 3 |
| All companies marked inactive by YC | 3 | 4 |
About two thirds of each batch sells to businesses (105 of 165 in W25, 113 of 166 in S25), and 102 W25 and 114 S25 companies are based in San Francisco.
What counts here: outside equity and strategic rounds with an announced amount, from January 2025 through October 25, 2026. Funding announced together, such as a seed and Series A, counts as one round. YC’s $500K standard deal (a fixed 7% for $125K plus a $375K SAFE) and rounds closed before a company joined YC are excluded.
Which W25 AI startups raised the most?
W25 has had six more months since demo day than S25. Ten W25 AI startups have raised $10M or more in outside money, and seven have reached a Series A.
| Company | What it does | Counted here | Largest round | Lead of largest round | Announced |
|---|---|---|---|---|---|
| Harper | Commercial insurance brokerage run on AI | $47M | $47M seed and Series A | Emergence Capital | Feb 2026 |
| Mastra | Open-source TypeScript framework for building AI agents | $35M | $22M Series A | Spark Capital | Apr 2026 |
| Solidroad | Reviews and trains human and AI customer support agents | $31.5M | $25M Series A | Hedosophia | Apr 2026 |
| AfterQuery | Expert-written training data and benchmarks for AI labs | $30M | $30M Series A | Altos Ventures | Apr 2026 |
| Spott | AI applicant tracking and CRM for recruitment agencies | $24.2M | $21M Series A | Balderton Capital | Sep 2026 |
| Mundo AI | Audio and video training data and evaluations for AI labs | $20M | $20M Series A | GreatPoint Ventures | Aug 2026 |
| Browser Use | Open-source tool that lets AI agents use websites | $17M | $17M seed | Felicis | Mar 2025 |
| HUD | Training environments and evaluations for computer-use agents | $16M | $16M Series A | Standard Capital | Jun 2026 |
| Liquid Compute | Price indices and a planned regulated exchange for AI compute | $15M | $15M seed | FirstMark and Chemistry | Sep 2026 |
| Proception | Dexterous robotic hands for humanoid robots | $11M | $11M seed | First Round Capital | Jun 2026 |
Harper is the largest raise in either batch. It places commercial insurance for small and mid-sized businesses and uses AI to handle applications, submissions and underwriter back-and-forth. Emergence Capital led the $47M seed and Series A, with Y Combinator, Peak XV and Antler among the other backers.
Solidroad and Mastra both raised twice. Solidroad took a $6.5M seed from First Round Capital in June 2025 and a $25M Series A led by Hedosophia in April 2026. Mastra went from a $13M seed in October 2025 to a $22M Series A led by Spark Capital six months later.
AfterQuery’s $30M Series A, led by Altos Ventures in April 2026, valued it at $300M. Press reports in September 2026 put its valuation at $3.2B after a further round; the company has not announced that round’s size. Browser Use set the early pace with a $17M seed led by Felicis in March 2025, the same month as demo day.
The smaller W25 rounds cover a wide spread of products. Conntour ($7M seed, General Catalyst) searches security camera footage in plain language. Bindwell ($6M seed, General Catalyst and A Capital) designs pesticide molecules with AI. Woz ($6M seed, Cervin Ventures) was building apps with AI agents plus human engineers at the time of its round. Pickle (KRW 6B seed, about $4.4M, with Base Ventures, Rebel Fund and Pioneer Fund) builds a personal AI agent and real-time avatar.
Which S25 AI startups raised the most?
S25 has had about 13 months since demo day, yet its top round is close to W25’s. Wafer’s $40M Series A in September 2026, which followed a $4M seed led by Fifty Years in April, is the second-largest round across both batches.
| Company | What it does | Counted here | Largest round | Lead of largest round | Announced |
|---|---|---|---|---|---|
| Wafer | Runs open AI models faster in production | $44M | $40M Series A | Marathon Management Partners and Chemistry | Sep 2026 |
| Halluminate | Training environments for AI agents doing finance work | $30M | $30M Series A | Oak HC/FT | Oct 2026 |
| F2 | AI operating system for private credit funds and commercial banks | $29M | $14M seed | HighlandX | Jun 2026 |
| Kernel | Cloud browsers for AI agents | $22M | $22M seed and Series A | Accel | Oct 2025 |
| Dedalus Labs | Cloud machines and tool gateway for AI agents | $11M | $11M seed | Kindred Ventures and Saga Ventures | Oct 2025 |
| Vulcan Technologies | AI for drafting and reviewing government regulation | $10.9M | $10.9M seed | General Catalyst and Cubit Capital | Oct 2025 |
| Veritus | Voice AI agents for loan servicing and collections | $10.1M | $10.1M seed | Crosslink and Threshold | Feb 2026 |
| idler | Evaluation datasets and training environments for AI labs | $9M | $9M seed | Paradigm | Aug 2026 |
Kernel had the earliest Series A announcement in S25. Accel led a $22M seed and Series A, announced together in October 2025, about a month after demo day. F2 has raised three times: a $10M round when it spun out of Arc in September 2025, a $14M seed led by HighlandX in June 2026, and a $5M strategic investment in September 2026 from Golub Capital, which also uses F2’s software.
The S25 seed tier is crowded with agent infrastructure. Dedalus Labs ($11M), Manufact ($6.3M, Peak XV), AgentMail ($6M, General Catalyst) and Autosana ($3.2M) all sell tools that other AI companies build on.
Where did the follow-on money go?
Grouped by what they sell, agent infrastructure and developer tools lead on both count and money, with 11 companies and $115.8M. Insurance and finance is third, with nine companies and $104.1M, led by Harper and F2.
Six companies sell training data, evaluations or practice environments to AI labs, and they raised $112.9M, the second-largest group: AfterQuery, Mundo AI, HUD, Halluminate, idler and Design Arena. That is $18.8M per company on average, against $10.1M across all 58, the highest of any group with more than one company. Four of the six have reached Series A.
Compute and inference is small in headcount but large per company. Wafer, Liquid Compute, Osmosis and Luminal raised $70.6M across four companies, all of them working on the cost or supply of computing power for AI.
Single-industry products raised too. Spott (recruiting, $24.2M), Solidroad (customer support, $31.5M), Veritus (lending, $10.1M), Vulcan Technologies (government, $10.9M) and Caseflood.ai (legal intake, $3.2M) each sell one product to one type of buyer.
Who led these rounds?
Among outside firms, General Catalyst led or co-led the most rounds, four: Conntour, Bindwell, AgentMail and Vulcan Technologies. CRV (SalesPatriot, and Osmosis as co-lead), Felicis (Browser Use, Luminal), First Round Capital (Solidroad’s seed, Proception), Peak XV (The Prompting Company, Manufact) and Chemistry (Liquid Compute and Wafer, both as co-lead) led two each.
A lead investor is not confirmed for 18 of the 64 rounds.
What else happened to the two batches?
Seven more W25 and S25 graduates raised $38.6M in outside rounds over the same period for products that do not center on AI: satellites and space vehicles (Orbital Operations, Reditus Space), counter-drone interceptors (Perseus Defense), a fusion reactor for ships (Maritime Fusion), road-repair robots (Pave Robotics), a cloud security graph (SubImage) and a cross-border bank (Munify). They sit outside the totals above.
Some companies already have an outcome. YC marks seven companies across the two batches as acquired, including ZeroEntropy (W25), which raised a $4.1M seed led by Initialized Capital in June 2025, and Opennote (S25). Another seven are marked inactive.
What to watch next
S25 is now 13 months past demo day, the same age W25 was in April 2026, when Mastra, Solidroad and AfterQuery announced Series A rounds; Harper had announced its seed and Series A in February. Three S25 AI companies have reached Series A so far. Four more raised a seed of $10M or more: F2, Dedalus Labs, Vulcan Technologies and Veritus.
For the wider picture, see our seed-stage AI startups list, our Series A AI startups list, the AI agent startups funding guide and top AI infrastructure startups.
Methodology
AI startups are companies whose product is built on AI or built for AI companies, such as compute and training data. Funding covers outside equity and strategic rounds with an announced amount, from January 2025 through October 25, 2026, shown in the currency announced. Funding announced together, such as a seed and Series A, counts as one round. YC’s standard $500K investment and rounds closed before a company joined YC are excluded.
Frequently asked questions
How many AI startups were in YC W25?
At least 136 of the 165 companies in YC’s Winter 2025 batch (82%) describe an AI product.
How many AI startups were in YC S25?
At least 150 of the 166 companies in YC’s Summer 2025 batch (90%) describe an AI product.
How many W25 and S25 AI startups have raised money since YC?
Fifty-eight, 32 from W25 and 26 from S25, announced an outside round between January 2025 and October 2026. They raised $586.8M across 64 rounds.
Which YC W25 startup raised the most?
Harper, an AI insurance brokerage, with a $47M seed and Series A led by Emergence Capital and announced in February 2026.
Which YC S25 startup raised the most?
Wafer, which speeds up AI inference, with a $40M Series A co-led by Marathon Management Partners and Chemistry in September 2026.
Does the YC standard deal count as a funding round here?
No. YC invests $500K in every company it accepts. This article counts only outside rounds raised after a company joined YC.
What kinds of YC AI startups raised the most?
Agent infrastructure and developer tools raised the most in total ($115.8M across 11 companies). Companies selling training data and evaluations to AI labs raised $112.9M across six, an average of $18.8M each.
About the author
Editorial Staff
The Editorial Staff at Bot Memo is a team of writers, analysts, and AI agents dedicated to mapping the global AI startup ecosystem. Led by Chintan Zalani, the team tracks thousands of funding rounds, classifies companies across verticals, and distills it all into actionable intelligence for investors and founders.
