Y Combinator Startups in Seattle 2025

Silurian is building foundation models for simulating Earth, starting with weather. From assessing the risk of wildfires to predicting the energy grid load, we provide an infrastructure layer for our planet. Our frontier models push the boundaries of what can be simulated on Earth and improve decision making across vital sectors including energy, insurance, agriculture, and logistics.

Clearly AI automates security and privacy reviews with AI. We performed hundreds of reviews at Amazon and Moveworks and now we're building the product we wish we had. Our users complete reviews in minutes instead of days. Emily and Joe are technical co-founders and senior engineers. We met in 2019 while working on an Alexa security review.

(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.

We have built a universal text-to-sound AI generator for musicians and sound designers. Music producers build songs with samples that they've hand crafted with our AI, and sound designers can incorporate generated sound effects into film, TV, and video games. With personalized generations and training data hand-picked by your favorite artists, Soundry AI is your new best friend in the music creation process.

Manifold is revolutionizing the spot freight procurement process for Carriers, Brokers, and Shippers. Our inaugural product transforms the booking process for spot shipments, significantly reducing empty miles and increasing revenue. We do this by aggregating spot shipment opportunities from a variety of shipper and brokerage sources into a single location. Andrew and Oliver bring deep domain expertise of freight from their pivotal roles at Convoy, where they were engineering leaders automating processes that were scaled to handle over 10,000 weekly shipments. This background has been instrumental in shaping Manifold's innovative approach. In just two months since launching Manifold has achieved $5,100 in monthly revenue, showcasing the pressing demand for our product. Manifold is poised to transform this $100+ billion industry. Not only will we streamline spot freight procurement operations but we will also redefine the industry's cost structure for the better.

Terrakotta is a power-dialer that lets sales reps leave AI-generated voicemails. Our first customers are Commercial Real Estate brokerages that use Terrakotta to clone their brokers voices, dial prospects and when no one answers, leave an A/B tested, personalized voicemail that gets a callback.

VetRec automates the process of taking clinical notes for veterinarians in a matter of seconds. Veterinarians should just review clinical notes, not spend time creating them. A visit with a pet is precious and 100% of the focus should be spent on the pet, not on notes. VetRec is the veterinarian's best friend.

Talc helps medical research teams pull events and metrics out of their data at a fraction of the cost of using human abstractors

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.

Boundary is building BAML -- a programming language to build AI agents. We used to code in assembly, and moved on to C. From C, we moved on to higher level languages like Python. Now we are going from Python to natural language. What does the code look like when 50% of the business decisions is decided by an AI agent / prompts? How do you test these AI components? We made BAML to address these problems. BAML helps has built-in tools to test, observe, and work with structured LLM outputs / tool calling natively in the language 10x faster. With BAML you can also instantly parallelize LLM Calls, or react to certain events or changes in your pipelines, without having to write any boilerplate. It's like using 'React' for AI. BAML code can used from any other language -- providing a standardized way to organize and declare any LLM or AI code.

Decohere is building product and infrastructure for real-time generative AI. We enable our customers to iterate towards their creative vision without waiting for long-running GPU jobs.

Matano is a modern SIEM, built for cloud-first security teams. It replaces traditional SIEM databases like Splunk or Elastic with a cybersecurity platform built on top of a cost-effective Security Data Lake.

Radical’s StratoSats are autonomous platforms that provide satellite-like services on demand. They fly within Earth’s atmosphere to provide persistent, high performance infrastructure across applications in earth observation, connectivity, and more. Unlike satellites, StratoSats navigate freely without the need for rocket launches or orbits - reducing costs, increasing flexibility, and ensuring customers get the targeted coverage they need.

Aurelian automates non-emergency calls for 911 centers. Our AI-powered operator instantly routes, triages, and resolves calls so citizens get exactly what they need and 911 dispatchers get to focus on emergencies. Upwards of 80% of total call volume faced by public safety agencies are administrative calls e.g., citizens trying to pay parking tickets or reporting a power outage. Aurelian lessens this burden and lets 9-1-1 dispatchers deal with actual emergencies. To date, Aurelian has automated hundreds of thousands of calls and sent over 10,000 emergent calls (that typically would've sat on hold) to the 911 line to be handled immediately.

Intuned is an AI enabled cloud platform to author, deploy, and monitor integrations to extract web data and execute browser automation. We enable engineers to build reliable integrations to access data and complete actions on other web services when official APIs are not available or complete.

Chordio is an AI-powered design review tool that helps product teams catch issues early, reduce QA grunt work, and ship polished interfaces with confidence. It works across Figma (plugin) and web (Chrome extension), so it's easy to incorporate into an existing design-development workflow.

The platform powering human like phone calls at AI speed

Instant Labs started in 2005 by building the fastest domain search engine on the internet: https://instantdomainsearch.com. People have performed over 2.5M searches and purchased 250K domains with our free tool.

VacationHomeRents helps users explore and compare vacation rental options across many listing platforms such as Airbnb, VRBO, Booking.com, etc.

Uberduck makes tools high-quality audiovisual content creation tools for product companies, brands, agencies, and musicians. We offer audio generation, image generation, and video generation functionality, including enterprise workflow APIs to power end-to-end video creation experiences. Vocal samples and full songs produced by our text-to-speech, text-to-singing, text-to-rapping, lyric video generation, and voice conversion technologies power: - AI remixes and original songs for musicians ranging from hobbyists to the largest DJs in the world. - Personalized musical content in marketing campaigns. - A variety of music-related consumer experiences built on top of our APIs.

Cash Flow Portal is an investment management platform for real estate. We launched 5 months ago, and we have 6-figure ARR, growing 50% month over month, with 300 syndicators and 3,000 investors. We’ve grown quickly because I am a syndicator myself. Having raised $20MM for my own deals, I know how painful it is to manually prepare Docusigns, send wire instructions and wrangle investors. I also happen to be friends with 2,000 other syndicators just like me needing a solution for managing their investors. I’m not just a syndicator. I spent most of my career as an engineering leader at Lyft, Twitter, and Amazon. $20K ARR per syndicator gives us a $2B TAM. Having achieved my own financial freedom through real estate investing, our mission is to serve all real estate investors and help them achieve financial freedom.

Strac is an agentless Data Discovery (aka DSPM - Data Security Posture Management), Data Classification & DLP (Data Leak Prevention) that automatically discovers, classifies and remediates sensitive data (alert, label, redact, mask, block, delete). Strac protects SaaS, Cloud, Gen AI, Browsers, On-Prem and Endpoints like O365, Slack, GDrive, AWS, Salesforce, ChatGPT, Jira, Mac, Zendesk, Azure, On-Prem (On-Prem, MS SQL SAP) and 40+ integrations. Strac protects enterprise companies like UiPath, Databricks, thredUP, B Capital, Crypto (dot) com!

LifeAt is your space to focus and complete tasks. Our mission is to help the 100M+ knowledge workers get into their flow state with video content and task management. Our customers get through their daily tasks twice as fast while feeling great at the end of the day! Well funded by Meta (Facebook), Line, Y Combinator, Goodwater, and other top VCs. Loved by over 1M+ users across the world and shared by over 500K+ followers across Tiktok/Instagram/Twitter. Come shape the future of focus and productivity!

Equipt Health makes it easy for any healthcare company to offer prescription medical devices to patients. We handle the whole process: the packaging, the logistics, the clinical (via our provider network) and technical support, and the return of data from connected devices. We're starting with the diagnosis and treatment of sleep apnea at heliosleep.com.

We have built a platform that enables drug discovery and development for previously undruggable genome regulators ("the regulome"). We accomplish this by moving drug discovery out of artificial systems where regulome proteins fail to function properly, and back into live human cells. Our technology combines innovations in automated cell processing, next-gen proteomics, and advanced data analytics to measure a drug's effect on the entire regulome in one experiment.

Stoke Space delivers goods to and from orbit using 100% reusable rockets designed to fly daily.

Truss is an all-in-one banking and payment automation platform for construction businesses. With Truss, construction companies can manage bill payments, receivables, and corporate cards in one place. They can save time on manual data entry by integrating Truss with their existing tools and automating the full billing cycle, from invoicing and reconciliation.

aSim lets you build and share apps with friends. Prompt > Run > Remix > Repeat, and you'll have the next TikTok in no time.

Awtomic powers DTC brands with an easy-to-use subscription management and discovery platform. Starting with a Shopify app, we'll give merchants the subscription product power of premium subscription brands like Dollar Shave Club and Ipsy. As we grow our support for more eCommerce platforms and merchants, we'll help customers discover new brands through cross-sells and make it easier for them to manage their subscriptions in one place.

We founded Inspectify with the goal to make a platform that helps inspectors, real estate professionals and home buyers alike. We see a tremendous opportunity to apply the latest technology to make inspectors more proficient and effective and make home inspections more engaging and value add to home buyers. We are just getting started, but are excited to provide much needed disruption in the space!

Our mission is to empower the world’s hiring teams to grow engaged, high-performing organizations - by delivering human connection at scale through innovative technology, commitment, and fairness. High-volume hiring is extremely broken - it is inefficient, ineffective, and biased. Our mission is to fix what is broken. We believe great hiring processes are centered around quality conversations between candidates and employers and a future where every candidate’s journey starts with a conversation - a future where candidates are considered without bias or archaic artifacts like resumes and cover letters.

Construction costs are climbing out of control, there is a declining construction workforce that gets smaller with every recession. Meanwhile, we’ve got a housing crisis in our major cities. Green Canopy NODE is the combination of NODE - construction technology start up that develops a house assembly kits that we manufacture in our factory in Seattle, and then ship flat-pack - like Ikea, and Green Canopy a vertically integrated developer, general contractor and real estate fund manager already operating in Seattle and Portland. We are continuing to develop and launch construction technology solutions including prefab components and software into our pipeline of residential projects ranging from small apartments, town houses, single family homes and small dwellings. Our mission is to build homes, relationships, and businesses that help regenerate communities and environments.

Latchel is the only end-to-end platform that automates maintenance coordination and delivers best in class resident amenities. We service over 80,000 homes across over 400 customers in all 50 states of the US. We’re growing rapidly and need a Product Designer to continue our rapid growth trajectory.

Gordian is pioneering seamless, personalized travel powered by world-class software. We don’t remodel legacy platforms — we invent what's next. Built on the values of freedom, impact, and ownership, we emphasize in-person collaboration, deep thinking, and bold execution. We believe in a high-talent, low-ego team with the energy to build something extraordinary.

Rebellyous Foods is a food manufacturing technology and production company defined solely to catapult meat alternative production toward price parity with animal-based meat. Rebellyous implements novel food manufacturing equipment and processes in large-scale production to produce low-cost plant-based meat at high volumes. These goals are achieved through uniquely designed food products, the use of high-throughput manufacturing automation and ‘smart’ production centers, and the development and utilization of new innovative low-energy manufacturing tools. Working closely with industry partners, Rebellyous makes plant-based meat sustainable, affordable, and widely available.

Worklytics identifies leading drivers of employee engagement, without the need for repetitive surveys. It does this by passively analyzing anonymous collaboration data, in tools like Google Workspace and Slack, and detecting patterns that lead to greater employee satisfaction. Worklytics uses these insights to promote positive organizational change by proactively nudging leaders and managers.

Sigma Genetics develops devices that can deliver DNA, RNA, and other charged molecules into cells by using magnetic fields. When compared to conventional electroporation, this technique has several key advantages, which include: the absence of arcing, the ability to scale, and the benefit of being non-invasive for in vivo applications. This platform technology can be applied to a wide range of applications- cell therapies, cancer drug delivery, DNA vaccines, biopharma manufacturing, and cosmetics.

BloomAPI simplifies how medical records are transferred. Today the majority of records are still moved by fax and couriers. Patients, Doctors, and Insurance companies all benefit when medical records are available when they are needed for the care of patients. We make this possible.

Deako believes that everyone should be able to enjoy the wonderful experiences of smart lighting, regardless of their budget. We invented the modular light switch, giving homeowners maximum flexibility to customize and upgrade their systems, at any time, in minutes and without turning off the power. Deako’s beautiful designer switches are like nothing else on the market today. Deako Smart Lighting has been named the #1 Smart Lighting Control System by TecHome Builder, Top 25 Innovative IOT Companies by Entrepreneur, featured in “I Want That!” episode on DIY Network, Top 50 most promising Startups by Bloomberg, and “Changing The Way Builders Spec Light Switches” - Builder Magazine.

Mason is the fastest way to take smart devices from idea to end user. Whether building a single-use device from scratch or scaling a line of smart products, with Mason it’s 20x faster and 10x less costly to build, deploy and scale. Digital transformation is a modern requirement but operating a hardware-dependent initiative is hard – thousands of hours and millions of dollars are at stake. The Mason Smart Device Platform is the only fully managed infrastructure for developing and delivering dedicated devices. It offers flexible usage-based pricing for fleets of devices and manages the underlying complexity of all associated backend services, making software delivery on a smart product line—whether it’s a tablet, wearable or new form factor—as simple as delivering software in the cloud. This frees innovators to focus on what matters: application development, feature specification and UX. Granular access to add, remove or lock down capabilities makes it possible for highly customized products to be built as envisioned. Mason offloads hardware investment risks and logistics, including inventory procurement, warehousing and supply chain management. With options like zero-touch provisioning, devices can work perfectly out of the box without end user intervention. Remote fleet management, troubleshooting and automated software updates by Mason ensure security and positive end user experiences. Organizations of all sizes rely on Mason to bring innovations and hundreds of use cases to market without reinventing the wheel. Smarter from start to finish with Mason.™ AWARDS * 2023: Best Places to Work & Best Startups to Work For, Built In Seattle * 2022: Best Places to Work & Best Small Places to Work, Built In Seattle * 2022: IoT Health & Wellness Innovation of the Year, IoT Breakthrough * 2022: Bronze Stevie® Award - Emerging Technology, The 2022 American Business Awards® * 2021: Deloitte Technology Fast 500™, Deloitte * 2019: Tech Impact Awards, Mobile - Silver, Seattle Business magazine Follow us on LinkedIn | https://www.linkedin.com/company/mason-america/

Helion is creating the world’s first fusion power plant, enabling a future with unlimited zero-carbon electricity.

Dyspatch by Sendwithus is a powerful communications platform built around advanced email content management. Our platform simplifies transactional email creation with a robust API, an easy to use editor, and built-in device testing, allowing for truly collaborative email strategy and execution. A centralized hub for email creation, approval, and publishing, our cloud-based solution empowers Product, Marketing, CRM, and Loyalty teams to efficiently build and test meaningful, dynamic communications without involving developers or deploying code. And with built-in support for 300+ locales, your teams can seamlessly manage localized content for global communications. Easily connect your cloud email provider or customize your integration to connect to your digital messaging service. Upload your existing templates in minutes. And from there, you’re well on your way to optimizing every email you send.

Wevorce is fixing divorce by ensuring kids come first, costs stay affordable, and the transition is appropriately paced, so that couples can focus on parenting, not fighting. For families, the Wevorce experience stands in stark contrast to the traditional adversarial approach. Instead of each spouse "lawyering up,"​ Wevorce brings them together to work with a specially-trained attorney-mediator who guides the couple through a defined, but fully customized, settlement process. Additional experts in finance and parenting are brought in as needed to ensure the settlement g... See More

RescueTime helps you set boundaries, protect focused work time, and achieve work/life balance by shedding light on how you spend your time, improving your focus, and helping you find more time for the things that matter most. We are a distributed company with members spread throughout the United States.

OpenPipe is an SDK that abstracts away fine-tuning custom models. We capture your existing provider’s prompt-completion pairs in the background and use them to create a new model that is faster, cheaper and often more accurate than the original.

highlight.io is the open source, full-stack monitoring platform. With just a few lines of code, Highlight makes it easy to understand what's slowing down your users and swiftly address errors and regressions on your web app. Imagine that you have a customer reporting an issue on your web app. With highlight.io, you can playback their exact interactions to reproduce the bug and get notified of any future errors that could happen. That being said, we’re just getting started! We have plans to go way deeper into your observability stack to give you all of the visibility you need. Join us on this journey: - Star us on GitHub (https://github.com/highlight/highlight) to keep up with releases and news. - Join our Discord (https://highlight.io/community) to share product feedback and thoughts.

Worksphere helps companies manage a hybrid workplace where employees work from the office and from home. We allow employees to reserve a desk, know who will be in office, and better coordinate in-person meetings. Companies can let go of unused office space and save money.

We build software to help restaurants manage their third-party delivery online orders.