From Moon Hotels To Cattle Herding: 8 Startups Investors Chased At Yc Demo Day

Investors person flocked to Y Combinator’s Demo Days for years to get their hands connected promising startups building cool tech. After all, nan accelerator has produced immoderate of nan biggest tech companies successful nan world, from Airbnb and Reddit to Dropbox, Zapier and Stripe.

That’s why we make it a constituent to support an oculus connected nan arena to spot nan astir absorbing companies from each batch. As I’ve been doing astir each 4th now that nan accelerator has moved to 4 cohorts a year, I asked astir a twelve investors which startups were astir successful request astatine Y Combinator’s Winter 2026 Demo Day earlier this week.

To guarantee our database included genuinely sought-after standouts, a institution had to beryllium flagged arsenic a ‘fave’ by astatine slightest 2 different task superior investors to make nan cut.

As for valuations, I’m proceeding that astatine slightest a mates startups person raised costs astatine a $100 cardinal value tag, though notably, those startups are already bringing successful run-rate gross of $1 cardinal aliases more. Even for nan little buzzy startups not connected this list, nan “default” valuation this 4th seems to beryllium astir $30 million, which investors told maine is astir two-fold nan existent seed marketplace average.

Without further ado, here’s nan list:

Beyond Reach Labs

What it’s building: Deployable star arrays for satellites.

Why it’s a fave: The startup claims it has developed star arrays that are nan size of a eating array astatine launch, but unfold to nan size of a shot section erstwhile they scope orbit. The founders opportunity their strategy tin summation disposable powerfulness ten-fold while slashing costs by 88%. Beyond Reach already has a formation planned for 2027, and says it has secured $325 cardinal successful letters of intent from starring abstraction companies.

Byteport

What it’s building: A ridiculously accelerated record transportation protocol.

Why it’s a fave: According to Byteport’s laminitis Jayram Palamadai, existing record transportation protocols for illustration TCP are excessively slow for nan AI age. That’s why he built DART, short for Dynamic Accelerated Record Transfer, which tin apparently transportation ample files astatine an mean of 10 times faster than TCP, and moreover up to 1,500 times faster connected “reliable connections.”

Hex Security

What it’s building: Continuous AI-powered information testing tools.

Why it’s a fave: To conflict hackers utilizing AI to motorboat non-stop cyberattacks, Hex is building AI agents that tin enactment arsenic penetration testers, constantly probing for vulnerabilities and information gaps successful companies’ infrastructure. By automating what was erstwhile a manual process performed infrequently, Hex claims it tin forestall attacks astatine a fraction of nan cost. The startup claims it has crossed run-rate gross of much than $1 cardinal successful conscionable 8 weeks, which whitethorn beryllium why VC investors, arsenic 1 personification told me, “were fighting” to put successful nan company.

Grazemate

What it’s building: Autonomous drones to herd and show cattle.

 Why it’s a fave: Moving cattle connected monolithic ranches is an costly and vulnerable undertaking, often involving helicopters and motorbikes. GrazeMate’s founder, who grew up connected a 6,000-head cattle position successful Australia, saw a measurement to make life easier for ranchers, truthful he dropped retired of assemblage wherever he was pursuing a robotics degree.

GrazeMate’s drones tin automatically guideline cattle to different areas of a ranch, estimate animals’ weight, writer readiness and growth, and tin travel pre-specified way plans.

GRU Space

What it’s building: Permanent lunar infrastructure, starting pinch a edifice connected nan Moon.

Why it’s a fave: “Humanity will go interplanetary. It’s a matter of not if, but when, and nan clip is now,” says GRU Space laminitis Skyler Chan, a caller Berkeley grad who antecedently built package astatine Tesla and worked connected NASA-funded abstraction tech.

Chan claims his startup has developed a “moon factory” that tin move lunar ungraded into structural bricks, which he plans to usage to build a luxury edifice connected nan satellite arsenic a “wedge” for broader lunar infrastructure. GRU’s astronomical aspirations, including its extremity to unfastened nan first lunar edifice by 2032, person made it 1 of nan astir talked-about startups of this YC batch. The institution has already secured $500 cardinal successful letters of intent, an invitation to nan White House, and moreover a preservation from nan Trump family.

Luel

What it’s building: A marketplace for human-captured information to train multimodal AI.

Why it’s a fave: Founded by 2 UC Berkeley dropouts, Luel is building a information marketplace that connects AI exemplary makers pinch contributors who tin taxable “daily-life” activities, specified arsenic ironing aliases patient-doctor conversations, to supply audio, video and image data. The institution claims it’s generating ARR of astir $2 cardinal wrong six weeks, fueled by precocious request from robotics and sound AI labs.

Pax Historia

What it’s building: An alternative-history strategy crippled powered by AI.

Why it’s a fave: Pax Historia allows users to rewrite history successful a measurement accepted strategy games can’t. Using generative AI, nan crippled responds to infinite, analyzable geopolitical scenarios, from “What if Rome ne'er fell?” to “What if nan USA took complete Greenland?” The founders declare nan crippled presently attracts 35,000 regular users who person played astir 20 cardinal rounds.

Stilta

What it’s building: Agentic AI for intelligence spot and patent lawyers.

Why it’s a fave: Stilta’s founders declare that patent disputes tin costs up to $4 cardinal per case, mostly owed to manual archive reappraisal costs. The startup says its AI supplier tin hunt and analyse patents crossed databases and technological literature, redeeming some clip and ineligible fees.

The company’s agents are already being utilized by IP lawyers astatine pharmaceutical elephantine Roche. For investors, different charismatic facet is that nan founders hail from Sweden — caller Swedish successes for illustration Lovable and Legora person created thing of a “halo effect” astir companies from nan region, 1 VC investor said.