10 cool startups you should keep an eye on from Y Combinator's W25 Demo Day

One of Silicon Valley’s most storied startup accelerators, Y Combinator, held its Winter 2025 Demo Day on Wednesday, showcasing what its latest batch of 160 startups are cooking up. Some of Silicon Valley’s most successful startups — including Stripe, Airbnb, and Reddit — started out in a YC batch.

Today, YC’s newer startups are focused on building the next big thing in AI. In this batch, we noticed a surprising number of startups creating tools to enhance other companies’ AI agents. Rather than building their own AI agents, these startups are building support tools. There’s no shortage of companies building AI agent tools today, but these managed to stick out from the crowd.

There are some honorable mentions that didn’t quite make this list but still managed to catch our attention. There’s Optifye, a startup that’s building software to manage factory workers and was embroiled in a social controversy a few weeks ago. There’s also Artificial Societies, which runs AI simulations to test how well your LinkedIn posts will do in a simulated version of your network.

YC has always accepted some eye-catching companies, but here are the startups we think are worth paying attention to in YC W25.

Abundant

What it does:

API for agent teleoperation
Why it’s a fave: One of the key reasons Waymo has been successful at deploying autonomous robotaxis is because humans can remotely take over a vehicle if one ever gets stuck. Abundant took that same idea, teleoperation, and built a platform that applies it to all AI agents. Abundant says its API allows it to catch when an AI agent fails, and allows one of its human operators to step in and take over.

Browser Use

What it does:

lets AI agents navigate browsers
Why it’s a fave: Coincidentally, Browser Use went viral earlier this week because a Chinese AI agent, Manus, used its open-source tool to click through site menus and fill out forms on browsers. Daily downloads quintupled to 28,000, one of the founders told TechCrunch. As web-browsing AI agents such as OpenAI’s Operator are taking off, Browser Use seems to be offering a compelling open source tool that enables them.

GradeWiz

What it does:

replaces tedious grading work with AI
Why it’s a fave: Teaching assistants (TAs) are the backbone of any modern university, quietly grading papers for professors and doing other grunt work. But grading piles of repetitive papers might not be the best use of a TA’s time when they could be directly teaching students. Founded by Cornell TAs who openly declare that they “hate grading,” GradeWiz uses AI tools to automate the task so TAs can make better use of their time.

Red Barn Robotics

What it does: Red Barn Robotics has created a weeding robot called “The Field Hand” that is designed to remove weeds on farms.

Why it’s a fave: Weeds can be detrimental to farms, but manually removing them is labor-intensive. Red Barn Robotics’ weeding robot is said to be 15 times faster than a human and more cost-effective. The company has already secured $5 million in LOIs for the upcoming growing season.

Retrofit

What it does: Retrofit is a vintage clothing marketplace that uses AI to curate listings based on current trends.

Why it’s a fave: Shopping for vintage clothing online can be overwhelming due to the vast selection and varying quality. Retrofit simplifies the process by using AI to organize listings and offers a visually appealing website.

Splash

What it does: Splash develops autonomous patrol boats for sea border surveillance.

Why it’s a fave: Autonomous technology is gaining traction in defense, and Splash’s patrol boats offer a solution for monitoring sea borders. The startup has already demonstrated its boats’ capabilities by autonomously cruising 200 miles in the San Francisco Bay Area with an impressive 800-mile range.