Hard Tech Startups funded by Y Combinator (YC) 2025

Zephyr Fusion is building the first in-orbit fusion power source: a megawatt-class reactor enabling large-scale industry in space, at a fraction of the cost of equivalent solar. Founded by former physicists from Lawrence Livermore and Oak Ridge National Laboratories, Zephyr leverages decades of fusion research to deliver a compact magnetic confinement system designed to take advantage of the space environment.

At Axial Composites Industries we are building the first non-planar manufacturing cell to manufacture carbon fiber parts at the speed of software for the upcoming autonomous age We believe in the following: • Aerospace and robotics manufacturing is going exponential • Thermoplastic composites will be the foundational materials for such applications Our mission is to equip the West with novel composite manufacturing methods that will act as the backbone of the skyrocketing demand in autonomous systems. Our method prints stronger and lighter parts by leveraging fiber anisotropy to our advantage. We can manufacture large composite structures in a day rather than weeks. This not only allows for faster iteration cycles, but it unlocks new possibilities for composite manufacturing.

SigmanticAI is building an AI-native hardware development assistant that automates the entire RTL design flow, from natural language to synthesizable HDL and testbenches, inside a seamless VSCode fork. Powered by fine-tuned Verilog LLMs, reinforcement learning, and real compiler feedback, SigmanticAI iteratively refines code until it compiles and passes synthesis, no matter how complex the design. It’s like the Cursor for HDL design. In addition to code generation, SigmanticAI can generate token-level annotations and onboarding documents to accelerate ramp-up for new engineers. With support for both cloud and on-prem deployment, it integrates with existing EDA tools to dramatically reduce debug time, improve collaboration, and accelerate hardware design across teams

CUDA for phones & consumer hardware: Cactus is used by 3k+ developers and 100+ products to run AI locally on consumer hardware. It is open-source! Check out the repo: https://github.com/cactus-compute/cactus

Boost Robotics is building autonomous mobile manipulation robots to remotely perform manual tasks in data centers. The surge in AI applications is pushing data centers to scale faster than they can manage, leading to suboptimal operations and staffing shortages amid rising power and compute demands. We save data centers millions in insurance premiums and SLA violations by increasing the frequency of inspection and maintenance while reducing the time it takes to triage and address failures.

PowerMatrix provides the MOST efficient and compact next-generation high-performance power supplies for emerging technologies, such as GPUs, xPUs, AI server, datacenters, drones, EV, aerospace, etc. Based on patented circuit topology, embedded packaging, and novel magnetics, our power supply systems can reduce energy loss by up to 50%. We have developed several prototypes and are collaborating with world-leading customers.

We’re building quantum-accelerated AI servers so organizations building AI can exponentially speed up training and inference. And we’re making tools for AI researchers to integrate quantum capabilities into AI models and workflows.

HABIT will deploy on-demand robotic labor to you — and to restaurants, hotels, stores, and farms in your neighborhood. Our first vertical (the $45B car wash and auto detailing market) is high cost, labor intensive, and already offered in thousands of locations across America.

What if every experiment you wanted to run could be modeled using AI? Godela is an AI-powered physics engine that gives engineers faster, cheaper replacement to simulations and physical prototypes. No set up, no wait. Just ask—and get simulation quality result.

Cascade Space is building a turn-key communications system for lunar and deep space missions. Our ground station network and integrated software tools work together to maximize uptime and availability, while reducing spacecraft iteration cycles from weeks to hours.

Atum Works is building 3D ASML. Founded by Caltech and NASA engineers, we're starting the next scaling law of semiconductor manufacturing, this time in 3D.

Maritime Fusion is building fusion reactors for ships and off grid energy markets. En route on this endeavor we’re commercializing High Temperature Superconducting (HTS) cable technology for power distribution while advancing the physics basis of our HTS tokamak to decarbonize global shipping. Breakeven fusion is coming soon, but the first-of-a-kind (FOAK) reactors will be costly, high maintenance, and have low capacity factors, leading to 5–10x higher electricity cost on the grid. Maritime Fusion is pursuing the most widely accepted approach to fusion, the tokamak, but specifically designed for the marine environment where the challenges that arise between breakeven and a commercially viable energy source are alleviated. The market we're targeting requires 15x less power, lower up-time, and costs the same as alternative fuels but without any emissions. Since fusion does not use highly radioactive fuels or materials – unlike fission – we sidestep the vast majority of regulatory challenges and safety risks associated with nuclear energy. Our team brings over a decade of industry and research experience in plasma physics, nuclear engineering, and electrical engineering with backgrounds at SpaceX, Tesla, Columbia University, and University of Pennsylvania.

Optifye.ai does AI performance monitoring for factory workers We place cameras in factories and use vision AI to tell supervisors who's working and who's not in real time. The shop floor has historically been a black box. With Optifye, manufacturing companies can now accurately measure worker output and boost efficiency!

We are making reusable satellites for zero-g manufacturing. Our first full orbital recovery mission is set to launch in April 2026.

Forge Automation runs software enabled factories that deliver custom metal parts in four days or less. Instead of mechanical engineers having to wait two to three weeks for their low volume CNC parts, they can simply upload a CAD model on our platform and we will ship it out in four days or less. We aim to give mechanical engineers the "Amazon experience" for custom metal parts.

Altrina automates SOPs to give humans back their time to do what matters. We have already significantly improved organizational efficiency for local governments, law offices, insurance brokers, consulting firms, and hedge funds. Formerly General Agency/Tessa AI

Ultralight is a GPU-accelerated toolkit to embed modern HTML in games and native apps. Available for C and C++ on Windows, macOS, Linux, Xbox, PlayStation, ARM64 devices, and more. Developed in collaboration with leading game studios, built GPU-first on a new, lightweight fork of WebKit.

Finding new cures requires seeing what and where the abnormal molecules are in a diseased tissue, but current tools see less than 1% of those molecules. Biocartesian combines microscopy and new chemistries to see 50X more, offering unprecedented insights into disease biology and new therapies.

Sensei helps robotics companies scale and outsource their training data collection. Our hardware platform enables the collection of human-demonstration data at a tenth of the cost and twice the speed of current teleop approaches. Our software platform acts like Scale AI for robotics data: a large network of paid human operators use our low-cost collection platform to fulfill data-generation requests.

We’re building the next generation of warehouse robotics. In the US today, retailers spend approximately $10B per year paying human laborers to pick up and move cardboard boxes in warehouses. Existing solutions for automating this are expensive and difficult to install, which is why manual operation is still so prevalent. Our solution is different. We make swarms of small mobile robots that install into existing warehouses to provide a low-cost and robust automation solution for case picking and mixed-SKU palletization. Our novel technology allows these robots to be installed and operate at significantly lower cost than existing solutions while being both flexible and robust.

We build underwater data centers to cut power usage by up to 30%, operating GPUs cheaper and more sustainably. Our 1 MW capsule is being tested underwater in the SF Bay

Sorcerer is deploying a global network of persistent airborne sensors to fuel advanced weather forecasting. Our high-altitude balloons collect 1000x more data than existing systems and are already used daily by meteorologists to track extreme weather across the US and Central America.

1849 bio designs microbes enabling cheap metal extraction allowing miners to unlock value from low quality copper and gold ores. Surprisingly, the mining industry is one of the largest scale users of biotech in the world with biomining processes accounting for ~1% of global copper production. Biomining is ultra-low cost, running around ~$1/ton of ore vs ~$7/ton for conventional processes. Unfortunately, while biomining is cheap, it can’t be applied to over 80% of copper ores, leaving vast resources without profitable extraction methods. An estimated ~$800B of copper sit today in waste materials and stockpiles with negative unit economics. While a great deal of effort has been spent on optimizing microbial metal extraction processes, very little effort has been spent on optimizing the microbes themselves. To change that, we’re creating new biotech tools and platforms applied directly to the types of biology most relevant to miners. This enables us to develop new microbes and tackle some of the most difficult problems in biomining, unlocking billions in value from unprofitable resources while being more environmentally friendly than conventional processes. We’re world class microbial engineers. We met while doing our PhDs in synthetic biology, where we spent our time applying and developing the most advanced bioengineering technologies to engineer living cells. 

(Formerly known as Lumen Orbit) Starcloud is building data centers in space, initially to provide GPU compute to other satellites, and later to address the rapidly growing demand for energy caused by the deployment of AI. Falling launch costs give us access to abundant energy, passive cooling, and the ability to rapidly scale in space. In Partnership with NVIDIA's Inception Program, we are launching our demonstrator satellite in late 2025, which will have 100x more powerful GPUs than have ever been operated in space.

Quantum computers will allow humanity to understand the world at its most fundamental level, enabling the acceleration of drug discovery and the development of new materials. Currently, quantum engineers spend days, sometimes weeks, manually getting their silicon chips to operational conditions to realize two qubits. A qubit is the information-carrying unit of a quantum computer, analogous to a bit in a classical computer. We need billions of qubits to make a useful quantum computer. Therefore, automation software will be vital to realizing this goal. Conductor Quantum will develop AI software to remove the human from the loop, enable the scaling of silicon quantum technology and build a silicon-based quantum computer.

Spaceium builds fully automated space stations to refuel and repair spacecraft. We have secured $86.1 million in binding commercial contracts and have an additional $230 million in the pipeline. Additionally, we have 1 billion dollars in letters of intent. We have successfully tested our hardware, which will launch to space next year. Our fully automated space stations will efficiently store and transfer both cryogenic (extremely cold) and non-cryogenic fuels with zero loss during storage and transfer. And they can transfer fuel seamlessly to any spacecraft design using our proprietary modular robotic arm. Our customers include launch vehicles, orbital transfer vehicles, moon landers, and spacecraft that benefit from increased payload capacity and extended travel capabilities. Our long-term vision is to build service hubs along the space superhighway to connect Earth to Moon and Mars and help humanity to become multi multi-planetary species

Yondu is creating the robotic workforce of the future starting with logistics automation. We're deploying humanoid robots in the first flexible, drop-in picking automation solution designed for 3PLs.

Elodin creates flight software, simulations, and hardware for drones, satellites, and defense.

Care Weather collects the highest-accuracy global weather data to help governments and shipping companies adapt to extreme weather. The data is collected by Care Weather’s unique flat-panel radar satellite, which is 1000X more cost effective because it’s vertically integrated, gets more solar power, and sails on top of the atmosphere for a closer view of the surface. Our team includes CEO Patrick Walton (NASA Earth science fellow) and CTO Alex Laraway (mach 4 rockets). In the last 4 months, we built and launched the smallest radar satellite ever. We have $35M worth of LOIs, including one from the Air Force and others from cargo shippers. Care Weather is backed by Boost VC, Kickstart Seed Fund, Y Combinator, and more.

Zelos Cloud is the data platform for mission-critical systems that enables teams to observe, control, and test systems from prototype to production. The platform connects across entire ecosystems, capturing data from many protocols, enabling remote command execution, and facilitating team collaboration through shared workspaces and real-time annotations. By integrating data collection, processing, and visualization into one seamless pipeline, Zelos Cloud eliminates complexity and breaks down silos between engineering, operations, and quality teams.

Hubble is building a global satellite network that any Bluetooth-enabled device can connect to, even without cellular reception. Our mission in life is to get a billion devices connected to the network and unlock a new era of human-machine collaboration.

We're building autonomous robots to make surgery safe, easier and more efficient. Robots currently perform about 1/4 of surgeries but only help with the physical aspects. We use AI to make surgery cognitively easier. This has far greater potential to improve outcomes and reduce costs. Founded by 3x founders from medtech and autonomous vehicles, we're on track to be the fastest surgical robot to market of all time. First indication is prostate enucleation.

Auricle is a medical device company building a breakthrough neurostimulation implant to restore hearing in millions of patients who no longer benefit from hearing aids, get less than 60% on a word recognition test, but aren't prepared to make the jump to a cochlear implant. Our approach preserves remaining natural hearing through a reversible and less invasive surgery, addressing the key concerns that hold most patients back from getting a cochlear implant (currently the only treatment option for these patients). The company spun out of Stanford Biodesign having completed two acute human clinical studies demonstrating the approach will work. The team is now focused on developing their full implant system for their first clinical trial. Auricle addresses a currently unserved profile of hearing loss that affects a growing population of 3.5 million patients in the US and represents an immediately accessible $1.2B market opportunity with existing reimbursement.

The DROP by Rex.Fit is an AI wearable camera that automates nutrition tracking using computer vision. It has garnered more than 93k USD in preorders (~450 units) since its launch last month. The nutrition estimation and recommendation tech behind the DROP is already integrated as an API for fitness chains, generating hundreds of thousands of dollars in yearly revenue for them. The DROP is built by brothers, sports nutritionists and computer vision engineers from the Swiss Federal Institute of Technology (ETH Zurich).

Our planes fly 10 times further than battery electric alternatives, with a lower operating cost than fossil fuel powered aircraft. Our first product is a 15 seat aircraft with a range of 800 km that enters service in 2026 with launch customer Skytrans. Our team has over 85 years of aerospace experience and have developed, flight tested and certified aircraft at Google X, magniX, Heart Aerospace, Ampaire, Airbus, Boeing, Bombardier and Gulfstream. We have $145M in aircraft LOIs from 7 airlines in the US, Europe and Australia.

Polymath is building a general autonomy stack for cautious vehicles. Our software allows any industrial vehicle - whether it's a tractor in a field or a bulldozer in a mine, drive itself. We bundle together AI, ML, Controls, ROS, Safety and best-in-class deployment practices to enable our customers to tell automated vehicles to do via a REST API. We're on more robots than we have engineers, are seeing our revenue (and robotic fleet) grow rapidly, and are looking for folks who want to help automate the world.

Integrated Reasoning builds efficient computer processors that are tailored to the memory access patterns of Karp's 21 NP-complete problems. We’re making it 100x - 10,000x faster to perform computations like scheduling airline pilots or optimizing packing layouts for shipping containers.

Atomic's mission is to replicate high-skill trade knowledge of tool and die makers into AI that powers new manufacturing systems which are orders of magnitude more productive.

Enlightra develops mass-manufacturable fingertip-size multicolor lasers enabling ultrafast data communication and optical computing while providing up to 10x improvement in energy efficiency and cost reduction.

We bring Tesla autonomous manufacturing to every automaker and other producers. At Tesla, we were the core autonomous factory team and we’re now building the smart cameras and robotic guidance tools that provided the main advantages at Tesla

Flux Auto is building autonomous mobility technology to fully automate the movement and operation of vehicles in controlled spaces. Using Flux's solutions customers can reduce their dependency on human drivers, while also increasing productivity and reducing operating costs. Flux is currently deploying in warehouses, farms and mines.

NearWave makes a handheld imaging device that helps physicians select the right therapy for their breast cancer patients. This prevents patients from suffering through months of side effects caused by unsuccessful treatments.

AirMyne is building machines to capture & remove carbon dioxide from ambient atmospheric air so it can be utilized or sequestered downstream. Our team is based in Berkeley, CA.

AstroForge is an asteroid mining company. Instead of bringing back the entire asteroid, we break it up, refine, and return only what’s valuable.

Andson Biotech helps pharmaceutical companies measure difficult to detect chemicals that they need to measure while developing and manufacturing drugs like cell-therapies or biologics. Drug companies want to use our technologies to get fast and accurate chemical measurements they do thousands of times per day for drug development and quality control.

Seabound builds carbon capture equipment for ships. We're the only way for existing ships to reduce up to 95% of CO2 emissions and meet new global regulations.

Impossible mining is building underwater robotics vehicles which collect battery metals from the seabed without harming the environment. We have $500M+ in off-take LoI’s and have signed a partnership with a global offshore logistics company which holds a seabed mining exploration permit. We have also built the 1st PoC underwater robotic arm. Polymetallic nodules are rocks which are rich in critical battery metals. Specially nickel, cobalt, manganese and copper. These metals are the the most expensive part of EVs.

Wyvern is a space data company that will capture the highest resolution hyperspectral images from satellites that cost 100X less than satellites using traditional telescopes.

Palitronica builds and deploys cutting-edge solutions to defend critical physical infrastructure and its supply chain. By using side-channel information from endpoints, Palitronica provides a safe attack detection capability retrofittable to critical systems.

Odys Aviation (formerly Craft Aero) builds vertical take-off and landing aircraft for major airlines. We cut travel time in half on the world’s busiest routes by using city helipads and local airports. The company founders are electric propulsion and automotive manufacturing experts who have spent their careers electrifying transportation systems at Virgin Hyperloop, GoogleX, Volvo, and Fisker Automotive. We’ve won two USAF Agility Prime contracts, have pre-orders and options for more than 1,000 aircraft.