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Applications for the YC Winter 2027 batch are now open!
Apply by November 2: ycombinator.com/apply
Y Combinator retweeted
I’m excited to share that Mach9 has closed a $34M Series A co-led by @firstround and @BessemerVP , with participation from @Prudence_VC and @QuietCapital .
During the first week of my freshman year at Carnegie Mellon, I walked into Red Whittaker’s office wanting to build field robots. Red handed me blueprints of a nuclear waste storage tunnel and told me to turn them into a CAD model, simulate it, and then build a robot to actually inspect it.
Our robots and software helped infrastructure owners and engineers understand what was there and plan what came next. The problems we worked on had real consequences for people and their communities.
That experience shaped why we’re building Mach9.
So many of the smartest people in the world are building software to serve better ads or AI to optimize a sales process, while entire industries that keep the world running still rely on tools from a generation ago.
Civil engineering is one of them. While civil engineering teams are using tools like LIDAR that make collecting data on their projects super fast, turning that raw data into usable CAD drawings and designs still takes months of manual drafting. And there are simply not enough people to do the work.
At Mach9, we’re building AI CAD software to expand the world’s capacity to build and maintain the infrastructure people depend on. Our software turns reality capture data into centimeter-accurate CAD drawings, helping surveyors and civil engineers deliver projects faster.
We’ve brought together an exceptional team from SpaceX, Tesla, Apple, and NASA to tackle hard technical problems in an industry where better tools can have a lasting impact. We’ve already helped nearly 100 organizations deliver over 2,500 projects spanning 100,000 miles of infrastructure in all 50 states. Behind those numbers are real problems we’re helping customers solve:
- On I-8 near San Diego, Caltrans is using Mach9 to turn scans into an accurate inventory of road safety assets, helping their team plan upgrades to make California’s roads safer.
- Fibersmith is using Mach9 to help design fiber networks that bring high-speed internet to more than 120,000 homes and businesses in some of Louisiana’s most underserved communities.
I’m so proud of what our team has built, and grateful to the customers and partners who have shaped Mach9 along the way.
Whether you’re looking for better tools for your next project or want to help us build them, we’d love to hear from you. Join us in bringing civil engineering into the AI era
Y Combinator retweeted
My agents sent me 355 hours of reading this week. I can't read that fast.
We're launching Spacesheep (YC F26) to fix that: agents' work lands in a space your team can actually understand and work on together.
Try it: tell any agent "share this to spacesheep.dev"
Y Combinator retweeted
Today we're launching Astor 2.0: your personal investing agent.
Horizontal agents are cool. But my take is that vertical agents are the next big thing. Your investments deserve an agent that's tailor-made, fully regulated and built to last.
Free to start on iPhone, both app and iMessage: astor.app
Y Combinator retweeted
Most agent demos stop working when you close the chat. Ours accumulates knowledge even when we sleep.
@venkatGoku used our OSS autoresearch harness to research a better C++ factory scheduler. It beat an expert-designed solver on 29/30 fresh problems and runs with no LLM.
Y Combinator retweeted
In one out of four runs, an agentic compliance pipeline failed to escalate a violation to the Head of Compliance. This was despite the model being fully deterministic with 800 identical replies. The same banking manual still produced four different sets of obligations.
Y Combinator retweeted
AI agents and their users figured out Axel has better travel rates before we even launched with @ycombinator
They keep coming to us for cheaper flights and hotels (50k+ AI searches a day). So we're launching now.
The plane is fake. The savings are real.
helloaxel.com
Stop Overpaying for Travel | Meet Axel, Your AI Travel Agent
Axel launch video.
Y Combinator retweeted
We built a lie detector for AI.
Today we're launching Latent (YC F26). It reads a model's mind while it's answering and stops the wrong answers before anyone sees them.
Works with any model, at 500x less than paying another AI to check the work.
Years of interpretability research taught me one thing: the model often knows it's about to be wrong. It just doesn't tell you. Now it does.
Try it free at runlatent.ai
Y Combinator retweeted
Today @cristian_le0 and I are launching @Armorer_Labs
It finds real security issues in the AI agents that regulated companies build, and fixes them without interrupting the business.
If you lead security or engineering, book a demo at armorerlabs.com
Stepful (YC S21) trains people for healthcare jobs and helps health systems fill critical staffing gaps.
After training 30,000 students last year, they now work with 39 healthcare systems, including seven of the 10 largest in the US, and recently raised a $55M Series C.
In this fireside, YC's @sdianahu sits down with co-founders Carl Madi and Tressia Hobeika to talk about how they saw a broken path into healthcare jobs and built Stepful to fix it. They share how the company grew from helping individual students become medical assistants to working directly with some of the country’s largest health systems, and how AI is helping them make that training more personalized and scalable.
00:00 — Tackling the Healthcare Worker Shortage
03:40 — Building a Faster, Cheaper Path to Healthcare Jobs
06:57 — AI Tutors and Local Hands-On Training
Y Combinator retweeted
Today, @agentmail has processed over 1 Billion emails.
A year ago, we processed under 20 million.
So we figured it was time for AgentMail to grow up a little too :)
Y Combinator retweeted
I just stepped out of Legora’s NYC office. Hard to describe how special it is to see hundreds of people working on something that Max, Sigge, and Jake once only had each other to believe in. They will win this and everyone who doesn't know yet will know soon.
And they're hiring for all roles in NYC but especially engineers and product. legora.com/careers – at Hoboken, NJ
We have raised a $550M Series E at an $8.8B valuation, led by Atreides.
Every major existing investor is back in, and we’re welcoming Baron Capital, Capital Group, Fidelity, Glade Brook and J.P. Morgan. We picked investors who think in decades. Several of them work with law firms and legal teams every day, so they can see where the work is heading.
Lawyers are moving from AI assistants to agents that do multi-step work. The money goes there. We’re growing our teams across North America, Europe, Latin America and Asia-Pacific, and going deeper on the Legora aOS.
Thank you to the 1,000+ people at Legora, and to the 140,000 legal professionals who use what we build.
I say this a lot because I believe it: it’s the best time in history to be a lawyer. We're thankful to be a part of it.
Full story: legora.com/blog/series-e
Y Combinator retweeted
Shipping code shouldn’t mean hours of manual testing.
@Simulithic (YC F26) sends AI agents through your app like real users, across browsers, devices, and account types. It tells you what broke without you writing a single test script.
The teams that ship fastest will be the ones that can verify as fast as they build.
Get started today: simulithic.com
Y Combinator retweeted
Today Nik and I are launching horizontal. (YC F26): AI agents that run factory operations.
Robots build the product, but people still run the factory. Planners, logistics and quality teams keep plants in sync by hand, across emails, spreadsheets and a dozen disconnected systems.
As mechanical engineers, we've seen this firsthand on the shop floor. Those days are coming to an end.
Our agents do that work themselves, inside the systems the factory already uses.
horizontal-tech.com
Big day for YC W24!
Congrats @WeAreLegora and @useblacksmith!
Y Combinator retweeted
Excited to work with Mastercard to enable agentic commerce, with x402, @CoinbaseDev, and @base.
Agentic finance is going to transform the economy, as agents continue to get more work done on our behalf.
Mastercard is now helping agents pay for digital services.
Coinbase provides the agentic payments infrastructure to power each @Mastercard agent using @Cloudflare. Powered by x402 and the Coinbase facilitator.
If you’re building in agentic commerce, let’s talk.
Congrats to @MaxJunestrand, @siggelabor, and @WeAreLegora (W24) on their $550M Series E at an $8.8B valuation!
Legora’s agentic operating system is where more than 140,000 legal professionals and their AI agents do legal work together.
They went from $1 million to $100 million in ARR in under 18 months, and the next $100 million took less than six. The US, where Legora opened its first office in spring 2025, is now their largest market by revenue, with more than half of the AmLaw 50 as customers.
legora.com/blog/series-e

























