Open Source Startups funded by Y Combinator (YC) in the San Francisco Bay Area 2026

GitLab is the first single application for the entire DevOps lifecycle. Only GitLab enables Concurrent DevOps, unlocking organizations from the constraints of today’s toolchain. GitLab provides unmatched visibility, radical new levels of efficiency and comprehensive governance to significantly compress the time between planning a change and monitoring its effect. This makes the software lifecycle 200% faster, radically improving the speed of business. GitLab and Concurrent DevOps collapses cycle times by driving higher efficiency across all stages of the software development lifecycle. For the first time, Product, Development, QA, Security, and Operations teams can work concurrently in a single application. There’s no need to integrate and synchronize tools, or waste time waiting for handoffs. Everyone contributes to a single conversation, instead of managing multiple threads across disparate tools. And only GitLab gives teams complete visibility across the lifecycle with a single, trusted source of data to simplify troubleshooting and drive accountability. All activity is governed by consistent controls, making security and compliance first-class citizens instead of an afterthought. Built on Open Source, GitLab leverages the community contributions of thousands of developers and millions of users to continuously deliver new DevOps innovations. More than 100,000 organizations from startups to global enterprise organizations, including Ticketmaster, Jaguar Land Rover, NASDAQ, Dish Network and Comcast trust GitLab to deliver great software at new speeds.

OpenSpec is an open-source, spec-driven framework. We help developers plan complex features by creating lightweight spec documents that serve as durable context for their coding agents. With 20k+ GitHub stars, we’re one of the leading spec-driven frameworks, used by thousands of developers and teams to plan and ship with the coding agent of their choice. Our philosophy is simple: keep planning lightweight and iterative, and match how software actually gets built, messy, evolving, and real, without dragging teams into rigid, bureaucratic workflows.

Agent-first development environment. Emdash enables engineering teams to develop software faster, by running multiple coding agents in parallel. We're an open-source and provider-agnostic desktop application.

21st.dev is the largest React component registry for AI applications, used by 1.4M developers (200K MAU). We provide the building blocks to create AI agents and agent-powered apps: UI components, agent templates, and an SDK with built-in UI, tools, memory, observability, and managed infrastructure.

Skillsync helps companies find engineers based on their code. It creates structured skill profiles of developers based on their open source contributions on GitHub. Using a Cursor-like interface, companies can search for specific capabilities like "deployed custom neural nets on edge" then qualify, shortlist and engage with engineers already building in their domain.

Sourcebot is an open source code understanding platform for massive codebases. We’re used by thousands of engineers in some of the largest companies in the world, including NVIDIA, Red Hat, Wikimedia, and Arista Networks. Understanding code, not writing it, is the primary bottleneck for large engineering teams. For developers, this means onboarding onto complex codebases faster. For AI agents, it means getting the necessary code context to minimize hallucinations and maximize cohesion within the wider codebase. Sourcebot solves this by giving developers and AI agents the ability to regex search across millions of lines of code instantly, as well as ask questions across thousands of repos using any flagship reasoning model. Being open source and on-prem, we can get deployed in enterprises within minutes before other tools even get approval. We met a decade ago at McGill University and have been building together full time for over 2 years. We’ve personally felt the pain of understanding large codebases while working at Microsoft, EA, Ubisoft, Google, and Meta.

Epicenter is an ecosystem of open-source, local-first apps that share a memory. We store all your work—notes, transcripts, chat histories—in a single folder of plain text and SQLite. Every tool we build shares this memory: your text editor, personal assistant, etc.. It's open, tweakable, and yours. Grep it, open it in Obsidian, host it wherever you like. The choice is yours. Our vision is to build a personal workspace where you own your data, choose your own AI models, and replace siloed apps with open, interoperable alternatives. All while preserving authenticity and being free and open source. ❤️

Fluidize accelerates R&D for scientists and engineers by using AI to build and run simulations and experiments. Our platform speeds up development pipelines by automating setup, execution, validation, and scaling, allowing engineers to focus on their science.

Pangolin is an open-source, identity-based remote access platform built on WireGuard that enables secure, seamless connectivity to private and public resources.

Check out the project: https://github.com/cactus-compute/cactus

Zero empowers knowledge workers by transforming the way they manage their email. It intelligently summarizes important messages, helps complete tasks, and even enables users to chat directly with their inbox.

Morphik is open-source multimodal search for AI apps. We're used by customers ranging from space-tech teams searching across research papers to developers building brokerage agents.

nao is an open source framework to build and deploy analytics agent. Create the context of your analytics agent with nao-core cli: data, metadata, modeling, rules, etc. Deploy a UI for anyone to chat with your agent and run analytics on your data.

Better Auth is a comprehensive authentication framework for TypeScript that lets you implement everything from simple auth flows to enterprise-grade systems directly on your own database, embedded in your backend. It’s loved by developers all over the world and endorsed by leading voices in the ecosystem. On top of the framework, Better Auth also provides an infrastructure layer to help you scale with user management and analytics, bot and fraud detection, transactional email and SMS, global session storage and more.

Mentra is building the open source operating system for smart glasses. The smart glasses hardware is finally ready, so we're building the OS and app store to power the next computing platform.

superglue replaces brittle SQL scripts, cron jobs, and one-off connectors that power enterprise operations with clean, versioned syncs you can actually understand and trust. It rebuilds the logic behind integrations, so migrating systems, adding tools, or scaling processes no longer breaks everything. Companies running on superglue roll out AI projects faster, spend less on maintenance, and future-proof their business for continuous optimization.

Confident AI allows companies of all sizes to benchmark, safeguard, and improve LLM applications, with best-in-class metrics and guardrails powered by DeepEval. Built by the creators of DeepEval (12.6k stars, >3m monthly downloads), Confident AI is able to offer battle-tested, open-source evaluation algorithms while providing the infrastructure needed for teams to stay confident their LLM systems.

We enable AI to control the browser. Browser-use is the biggest open-source web agent project. We got 40k stars in the last 3 months.

Lingo.dev helps dev teams use LLMs for app localization and content translation. Lingo.dev Compiler helps React developers localize apps without rewriting the existing code. Lingo.dev CLI helps web and mobile teams use AI for producing perfect translations for their user interfaces and docs. Lingo.dev SDK helps use LLMs for real-time translations.

Unsloth helps builders create custom models better & faster using RL and custom kernels. We're developing the all in one solution to help you create highly-accurate custom models 30x faster with 90% less memory use. With over 10 million monthly model downloads and 40K GitHub stars, our mission is to make training and open-source the best it can be!

A Cursor-like AI-assisted, no-code IDE for building production-ready multi-agents. ✨ Start from a simple prompt to create fully functional agents with the Copilot 🧪 Test them in AI-simulated scenarios 🌐 Connect MCP servers and tools 📞 Interact through the Python SDK, a web widget, or a Twilio phone number ♻️ Continuously refine your agents by providing feedback to the Copilot Built on OpenAI's Agents SDK, Rowboat is the fastest way to build multi-agents!

Opslane is a developer-first Kubernetes delivery platform. Connect your repo and get previews, safe rollouts, and instant rollbacks — no YAML, no ops team required.

Ben and Jacob met in Calculus class in 10th grade, and tried founding a startup in high school — it didn’t go anywhere. During high school, Ben lead the frontend team for the World Health Organization’s COVID-19 App Team. After high school, Jacob went to Apple and Ben went to college. When there was an opening on his team, Jacob had Ben apply, and Ben left UChicago to go work at Apple. They spent about 2 years at Apple as Senior Engineers in the Conversational Engineering Department, before leaving to found Freestyle. Freestyle is directly inspired by what they saw as their failures of the tech they worked with at Apple.

Mem0 provides a memory layer for LLM applications, enabling them to remember and learn from user interactions over time.

Manaflow is an open-source applied AI lab building AI dev tools. We're the creators of cmux, the open source terminal for coding agents.

OpenFoundry is an open source platform that helps engineers build, deploy, and scale their open source AI stack 10x faster. Ship your AI stack with just one line of code. You could think of us as an open source alternative to Hugging Face. Learn more and check out a demo of this in action in our Launch YC post: https://www.ycombinator.com/launches/KhY-openfoundry-developer-infrastructure-for-open-source-ai

We work on benchmarking and improving the long-horizon capabilities of AI Agents. We build out specialised environments to improve the long-horizon capabilities of browser and computer use agents.

Tesseral is the open source platform for managing identity and access in business software. It provides enterprise-grade capabilities, including SAML single sign-on, SCIM provisioning, role-based access control, managed API keys, and audit logs, implemented in just a few lines of code. Tesseral unifies access management for employees, customers, services, and AI agents, giving organizations the flexibility to adapt to any deployment model and the authority to enforce security policies with precision. You can learn more by reading our docs at https://tesseral.com/docs or by checking out our GitHub at https://github.com/tesseral-labs/tesseral.

Onyx is the open source chat UI connected to your company’s docs, apps, and people. We ingest and sync from all sources of information (Google Drive, Slack, GitHub, Confluence, Salesforce, etc.) to provide a centralized place for users to ask about anything. Imagine your most knowledgeable co-workers, all-rolled into one, and available 24/7! Check us out on Github: https://www.github.com/onyx-dot-app/onyx Or visit our website: https://www.onyx.app/

Tracecat is the open source AI automation platform for technical teams. Purpose-built for security, reliability, and internal operations. We provide everything technical builders need to automate work — AI agents, workflows, cases, and over 150 integrations. Trusted by automation builders (open source and enterprise) across 500+ organizations from startups to Fortune 500 and federal agencies.

Superagent helps developers make their AI apps safe. We offer: - Red team testing — specialized attack agents probe your production AI for data leaks, harmful outputs, and unwanted actions - Structured reports with findings, evidence, and remediation guidance - A Safety Page to prove it to your customers — use it in sales, procurement reviews, and security questionnaires Built for companies selling AI into enterprises and regulated industries.

Tusk (YC W24) is an AI agent that helps developers generate unit and integration tests with codebase context. Tusk sits in CI and provides automatic coverage whenever software engineers raise a PR. Engineering teams use Tusk to prevent critical regressions while increasing test coverage.

Mattermost provides secure collaboration for technical and operational teams that work in environments with complex nation-state level security and trust requirements. We serve technology, public sector, national defense and financial services industries with customers ranging from tech giants, to the world’s largest banks, to the U.S. Department of Defense and governmental agencies around the world. Our self-hosted and cloud offerings provide team messaging, file sharing, integrations, audio and screen share, workflow automation and project management on an open source platform deployed by the world’s most secure and mission critical organizations. We co-build the future of collaboration with over 4,000 open source project contributors who’ve provided over 30,000 code improvements towards our shared product vision, which is translated into 20 languages.

Building a modern alternative to Salesforce: https://github.com/twentyhq/twenty

Khoj is an applied artificial intelligence company. We're a tiny team of hackers doing applied research and building safe, useful ai software for humans.

ParadeDB is an open source, ACID-compliant search and analytics database. Built on Postgres for update-heavy workloads.

Skyvern helps companies automate browser based workflows using LLMs and Computer Vision, fully automating manual workflows and replacing brittle or unreliable scripts. Examples include: 1. Automating materials procurement from commerce websites 2. Completing complex multi-step workflows (ie getting an insurance quote from Geico.com) 3. Automatically logging into portals and downloading invoices 4. Navigating legacy content systems to do data extraction or data entry

refine is an open-source, headless React framework for rapidly building enterprise web applications. It eliminates many repetitive tasks like ➡️ CRUD operations ➡️ State management ➡️ Routing ➡️ Authentication ➡️ Access Control ➡️ i18n and saves days of development time. So far, thousands of great projects have been built by 15,000+ monthly active refine developers. Use cases are ranging from admin panels, dashboards, and internal tools to B2B solutions and complex SaaS interfaces. refine is backed by a strong community featuring 16K GitHub stars ⭐️, 180+ contributors and 2,500 Discord members. Thanks to it's unique "Headless UI" approach, refine works with any custom design. It has also ready-made integrations with 4 most popular UI frameworks: Ant Design, Material UI, Chakra UI and Mantine. refine is totally backend agnostic and it can connect to 15+ backend services out-of-the-box, incl. custom REST & GraphQL API's. With refine, developers always have 100% control over their projects as they build, style and deploy the way they like.

At Reworkd, we're working on multimodal LLM agents that serve as the simplest way to extract web data at scale. Customers come to us with lists of 100s to 1000s of websites along with a data schema. Our agents traverse these websites, understand their structure, and generate code to extract data from them. We've been working on LLM agents since their inception and have received over 30k stars on GitHub and 1M+ users across previous agent products. If you're interested in our pilot program, shoot us an email!

OpenBuilder is the vibe coding platform that helps non-technical builders take their ideas to production. Instead of paying for credits and getting stuck. OpenBuilder offers unlimited build credits, gets you unstuck and ready for production. It's also an open platform where you have access to all of your code from day one.

Open source voice AI. Check out our docs for more information: https://docs.vocode.dev

Easily build & scale AI agents, functions, stateful services, and more. Open-source & self-hostable.

Reflex is the operating system for building mission-critical enterprise applications. Today’s enterprise stack is fragmented. Shipping an app requires stitching together multiple tools and coordinating across multiple roles. Reflex replaces that complexity with a single, unified platform to build, deploy, and manage production applications end-to-end. We empower teams to own the entire lifecycle of their apps — from idea to production — without needing specialized infrastructure, DevOps, or platform teams. We do this by providing solid, reusable abstractions at both the framework and infrastructure layers. Because we own the underlying open-source framework and the platform it runs on, we can manage the full lifecycle of the application seamlessly. With Reflex, teams securely connect to company data, use AI to build standardized applications on top of our open-source framework, and deploy with a single click to share across their organization. We’re replacing the fragmented enterprise stack — and the organizational bottlenecks that come with it. Founded by Alek Petuskey and Nikhil Rao, Reflex has powered over 1 million applications, earned 28,000+ GitHub stars, and is used by 30% of Fortune 500 companies for internal tools and data-driven applications.

Infisical is the leading open-source platform to manage secrets, certificates, configs, and access across your team and infrastructure. Infisical stores your secrets and injects them back into your development workflow, CI/CD pipelines, and cloud infrastructure. It comes with secrets versioning, point-in-time recovery, audit logging, automatic secret rotation capabilities, and more.

Customers expect your SaaS to integrate with all the software they use. With Nango, you ship integrations your customers love, fast. Leverage hundreds of pre-built integrations and unlimited customization.

Firecrawl is a web data infrastructure platform that converts websites into clean, structured data optimized for AI applications through a simple API. Originally built as an internal tool at Mendable to solve their own data ingestion challenges, the team recognized the broader need for reliable web data extraction and transformed it into a standalone product. The platform combines web search, scraping, and AI-powered parsing into a unified solution, focusing on the core developer priorities of reliability, speed, and ease of use. By abstracting away the complexities of web data extraction, Firecrawl serves as the foundational data layer that enables AI applications to seamlessly access and process web content in the exact format they need.

Medplum makes it easy to build healthcare webapps that are compliant and interoperability ready. Our open source toolkit allows healthcare providers write apps that are HIPAA compliant, SOC2 certified and FHIR native - streamlining payor connections, health system integrations and more.

Activepieces is an open-source (MIT) business automation software. For example, you can build automations to receive email and Slack notifications about new contacts add to your HubSpot CRM.

LanceDB is a new open-source vector database that can support low-latency billion-scale vector search on a single node. Built around a new columnar data format, LanceDB makes it incredibly easy to build applications for generative AI, recsys, search engines, content moderation, and more.