From Moon hotels to cattle ranching: 8 startups pitched at YC Demo Day

Investors have been flocking to Y Combinator’s Demo Days for years to get their hands on promising high-tech startups. After all, the accelerator has created some of the biggest companies in the world, from Airbnb and Reddit to Dropbox, Zapier and Stripe.

That’s why we make sure to keep an eye on the events to see the most interesting companies in each category. As I’ve been doing almost every quarter now that the add-on has moved to four rounds a year, I asked about a dozen of the most ambitious investors at Y Combinator’s Winter 2026 Demo Day earlier this week.

In order to ensure that our list includes what people want, a company had to be recognized as a ‘favorite’ by at least two investors in order to make the cut.

As for valuations, I hear that at least a few startups have raised $100 million in funding, although mostly, the startups are already bringing in $1 million or more. Even with a few startups not on the list, the “abandoned” valuation this quarter looks to be about $30 million, which investors tell me is double the seed market cap.

Without further ado, here is the list:

Beyond Reach Labs

What it is building: Satellites that can be deployed.

Why I like it: The founders say they’ve created solar panels that are the size of a dining table at launch, but expand to the size of a football field when they’re around. The inventors claim that their machine can increase available energy tenfold while cutting costs by 88%. Beyond Reach already has an aircraft planned for 2027, and has reportedly received $325 million in letters of intent from leading companies.

Byteport

What it is building: The fastest file transfer protocol.

Why I like it: According to Byteport founder Jayram Palamadai, existing protocols like TCP are too slow for the age of AI. That’s why they created DART, short for Dynamic Accelerated Record Transfer, which can transfer large files 10 times faster than TCP, and up to 1,500 times faster over “reliable connections.”

Hex protection

What it is building: AI-powered security testing tools.

Why I like it: To combat hackers who use AI to launch non-stop cyberattacks, Hex is developing AI assistants that can act as penetration testers, constantly looking for weaknesses and security gaps in corporate architecture. By using systems that were previously mostly built by hand, Hex says it can prevent attacks at a fraction of the cost. The startup claims to have passed $1 million in funding in just eight weeks, so VC investors are, as one person told me, “fighting” to invest in the company.

Grazemate

What it is building: Autonomous drones for cattle herding and monitoring.

Why I like it: Moving cattle into large feedlots is an expensive and dangerous operation, often involving helicopters and motorbikes. The founder of GrazeMate, who grew up on 6,000 cattle ranches in Australia, saw a way to make life easier for ranchers, so he dropped out of college to pursue a degree in robotics.

GrazeMate Drones can guide cattle to different pastures, estimate animal weight, grass availability and size, and can follow pre-defined routes.

Part of the GRU

What it is building: Permanent construction of the moon, starting with a hotel on the Moon.

Why I like it: “People will be interplanetary. It’s a matter of not if, but when, and the time is now,” said GRU Space founder Skyler Chan, a recent Berkeley grad who previously built programs on Tesla and NASA-funded space technology projects.

Chan says his startup has created a “moon factory” that can turn lunar soil into building bricks, which he plans to use to build a luxury hotel on the moon as a “mill” to make larger lunar structures. GRU’s space ambitions, including its goal of opening the first lunar hotel by 2032, have made it one of the most talked-about initiatives of the YC team. The company has already received $500 million in letters of intent, invitations to the White House, and reservations from the Trump family.

Luel

What it is building: Market human-generated data for multimodal AI training.

Why I like it: Founded by two UC Berkeley dropouts, Luel is building a data market that connects AI model developers with assistants who can provide “everyday activities”, such as ironing or talking to a patient doctor, to provide audio, video and images. The company says it is generating an ARR of around $2 million within six weeks, thanks to high demand for robotics and voice AI labs.

History of Pax

What it is building: Another historical game with the help of AI.

Why I like it: Pax Historia allows users to rewrite history in a way that traditional games cannot. Using advanced AI, the game responds to infinite, real-world challenges, from “What if Rome hadn’t fallen?” “What if the USA takes over Greenland?” The developers say the game currently attracts 35,000 daily users who have played nearly 20 million games.

From Stil

What it is building: Agentik AI for intellectuals and certified lawyers.

Why I like it: Stilta’s founders say patent disputes can cost as much as $4 million per case, mostly due to manuscript review costs. The startup says its AI assistant can search and analyze patents on websites and scientific documents, saving time and legal fees.

The company’s agents are already employed by IP lawyers at pharmaceutical giant Roche. For investors, another interesting thing is that the founders are from Sweden – recent Swedish successes such as Lovable and Legora have created a “halo threat” around companies from the region, one VC entrepreneur said.