From Moon hotels to cattle herding: 8 startups investors chased at YC Demo Day

Y Combinator’s Winter 2026 Demo Day showcased several standout startups attracting strong investor interest, with some companies achieving valuations around $100 million backed by substantial revenue. Investors highlighted eight particularly promising startups, each addressing innovative technological challenges across diverse sectors. Notable examples include Beyond Reach, which is developing deployable solar arrays for satellites that expand dramatically in size once in orbit, promising a tenfold power increase and significant cost reductions. Another is Byteport, whose founder created DART, a file transfer protocol that can be up to 1,500 times faster than traditional TCP on reliable connections, catering to the demands of AI-driven data transfer. Other highlighted startups include Hex, which uses AI agents to perform continuous security testing, automating penetration testing to prevent cyberattacks more efficiently and cost-effectively; and GrazeMate, which deploys autonomous drones to herd and monitor cattle on large ranches, improving safety and operational efficiency. Additionally, GRU Space aims to build permanent lunar infrastructure, starting