Developer Tools Startups funded by Y Combinator (YC) in the San Francisco Bay Area that are currently hiring 2026

Since graduating from YC, Amplitude (W12) has made it to IPO and beyond by helping cutting edge startups become category leaders. We’ve pioneered the digital analytics category to become the go-to solution for AI pioneers (Cruise, Midjourney), apps that touch millions of consumers (Doordash, Coinbase), and the best in B2B (Atlassian, Rippling, Canva). With product analytics, experiment, CDP, session replay, and more, Amplitude’s digital analytics platform shows you what your users love, where they’re getting stuck, and what keeps them coming back. You want to build a generational business, and we have the capabilities and pricing plans to guide you every step of the way. Check out our special deal for YC companies and get started on your analytics journey.

Building the communication infrastructure needed for fully autonomous agents

Moss is building the real-time semantic search runtime for conversational and multimodal AI. Our system enables voice agents, copilots, and chat interfaces to retrieve, reason, and respond in sub-10 ms, delivering the responsiveness that makes AI interactions feel truly natural. If you’ve ever built a conversational or voice AI product, you’ve felt the lag. That moment when an agent pauses and the illusion of intelligence breaks. The bottleneck is almost always retrieval. Each query hops across networks and databases, adding delay and cost. Moss eliminates that gap by keeping retrieval close to where the agent runs. Moss runs natively across browsers, mobile devices, and servers with an optimized vector index built in Rust and WebAssembly. It enables teams to build AI products that feel instant, contextual, and adaptive. The experiences that sustain engagement and unlock new kinds of interaction. For our customers, this translates into tangible business value: stronger user retention, higher conversion, and entirely new product categories made possible by real-time understanding. Moss is already powering production pilots across voice AI and developer platforms, achieving sub-10 ms retrieval and 70–90% token savings compared to traditional pipelines.

The fastest persistent computer for agents. Host long-running, stateful agents that never sleep in <250ms.

VibeFlow generates full-stack web apps from prompts with n8n-style visual workflows for the backend. Users of tools like Lovable or v0 can easily iterate over frontends because they can see them, while backends remain closed black boxes that are hard to evolve through prompting. VibeFlow opens up backend logic, making it visual and editable, with powerful integrations built in.

Luminal builds an ML framework and compiler that generates GPU code. Our stack 10x's model speed while simplifying deployment and cutting idle GPU costs Github: https://github.com/luminal-ai/luminal Discord: https://discord.gg/APjuwHAbGy

Embedder is a coding agent that can write, test, and debug firmware.

Autosana is the end-to-end testing layer for your coding agents, across iOS, Android, and Web apps. Step away from your laptop. Come back to full-stack features built and tested end-to-end, production ready. Autosana creates, updates, and runs tests automatically from your code diffs. Locally, it loops with your coding agent until every test passes. In PRs, it loops with cloud agents and shows video proof of your new feature or bug fix working end-to-end. No setup, no maintenance, just tests evolving with your codebase. Ship with confidence.

Nozomio is a product and research lab solving context, starting with Nia. Nia is a search and index API. We continuously provide context from docs, research papers, datasets, codebases, and more so agents never rely on stale data. Scalable, 5x cheaper, and reliable.

AgentMail is the email inbox API for AI agents. It gives agents their own email inboxes, like Gmail does for humans.

Manage a fleet of agents locally or in the cloud. 100% open source and free to use. Built to help you do your life's work.

Attune makes blazingly fast build tools that require zero migration effort. As AI enables developers to write code faster than ever, slow builds are increasingly becoming the bottleneck in development velocity. Developers regularly lose hours of productivity every day waiting for their builds. Imagine being able to write code in 1 minute, but needing to wait 30 minutes to compile, deploy, and test it. Existing solutions either require painful migrations to new tools (e.g. Bazel) or rely on just using bigger servers to run your builds. Instead, we do native, first-class integrations into compilers and build systems. With Attune, you don't need to integrate a new tool. Just make a one-line change from `cargo build` to `hurry cargo build` for 20x faster builds. Eliza (ex-Google) and Xin worked together for 3 years at FOSSA, where Eliza was Head of Engineering and Xin was Head of Product. Eliza brings a decade of programming languages and build systems expertise, while Xin brings a decade of experience building developer tools products, most recently as VP of Product at Teleport (S15). Having experienced the pain of slow builds firsthand across hundreds of production codebases, we're building the solution we've always wanted.

Blaxel is the perpetual sandbox platform for AI agents that need to run code fast. Unlike traditional sandboxes that expire or suffer from cold starts, our sandboxes automatically scale to zero after 1s of inactivity and resume in under 25ms with full memory state preserved — allowing you to keep millions of secure sandboxes on standby indefinitely. We also co-locate your agent logic alongside these sandboxes to eliminate network overhead, delivering near-instant latency for end users.

Infinite is a stablecoin payment processor. We offer businesses turnkey APIs and SDKs to instantly move money anywhere in the world at a fraction of the cost of traditional solutions.

Onlook is the fastest way for anyone to build, deploy, and iterate on websites and web apps. We built an open-source, visual editor for code that merges design, development, and AI. Since launching, Onlook hit #1 on Hacker News, was the #1 trending repo on GitHub—above DeepSeek—and has earned over 8,500 GitHub stars. Founded by Daniel Farrell, a designer of 10+ years and former Head of Growth, and Kiet Ho, an ex-Amazon and ex-ServiceNow engineer, Onlook is on a mission to finally solve the gap between design and development.

a0.dev is a platform that helps mobile developers build high quality apps in days instead of weeks by generating custom react native projects. We've launched top ranking apps that have been used by hundreds of thousands, and now we're creating the tools we wish we had to build faster.

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.

Quantstruct automatically creates and improves product documentation, implementation guides, and changelogs for API & SDK products, web-based enterprise software, and internal applications. Quantstruct identifies gaps in your knowledge base based on each product release or unfulfilled customer query. It uses multiple AI agents to search existing knowledge sources, test existing docs for validity and style guidelines, and clicks, scrolls, and uses enterprise software through a web browser to generate docs with embedded screenshots and video recordings. Quanstruct is available as a cloud service to start, targeting technical writers, content writing, professional services, and product teams. Traditional generative AI tools risk hallucinating critical API & SDK fields, even with RAG based approaches. Purely agent-based approaches risk providing unpredictable output that can diverge from desired documentation processes. Finally, no company’s review and publishing workflow is the same. Quantstruct is the easiest way to onboard and customize AI agents to continuously improve your documentation based on your customer needs and product evolution. https://quantstruct.com

Docs are integral to a great customer experience, but managing them is a challenging, multi-team effort. The most successful companies recognize that fantastic docs drive adoption and bad ones cause customers to churn. Promptless is used by fast-growing startups and Fortune 500 enterprises alike to automatically update docs based on feature releases, support tickets, internal Slack conversations, and more. Promptless is designed to be flexible—it can integrate with any docs platform, be triggered automatically from many workflows, and can pull in context from any internal knowledge source. With Promptless, documentation becomes a strategic advantage for growth, not a bottleneck or a liability.

Creative intelligence

Revyl is a AI-native mobile testing platform that automatically catches and triages bugs before they reach production.

Cekura helps Conversational AI companies with automated QA. From pre-production simulation and evaluations to production call monitoring, to assisting customers in setting up the CI/CD pipeline, we help in QA across the agent lifecycle. We are working with 75+ customers across healthcare, BFSI, logistics, recruitment, and retail. Some of the largest CCAS players and enterprises use Cekura to ship AI voice and chat agents reliably

HumanLayer is an IDE and collaborative cloud platform that helps software engineers solve hard problems in complex codebases. Ship 2-3x faster without AI slopping up your codebase.

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!

Coval is a simulation & evaluation platform for autonomous AI agents, helping engineers launch dependable assistants across chat, voice, and other modalities. We simulate thousands of scenarios engineers don't have to manually test their agents. Our CI/CD evaluations automatically simulate and detect regressions.

Run parallel agents in isolated workspaces. See at a glance what they’re working on, then review and merge their changes.

One-click GPU instances with persistent storage, snapshots, and hot-swappable hardware, with the lowest prices anywhere.

Cloudglue is the video context layer for AI. We make it easy for your AI to understand video. - Tinycloud - your AI agent for video, now open for beta: https://tinycloud.cloudglue.dev - Developer API Platform: https://cloudglue.dev

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

AI Agents have arrived. They are powerful enough to read, plan, and act across your everyday life and work. The question is no longer whether they can run canned demos to check the weather, it’s whether real teams can rely on them for critical work. We optimize for adoption over spectacle: useful, accountable systems that help top professional complete real tasks. Wordware is backed by Spark Capital, Felicis, and Y Combinator, with a $30M seed round. Our beautiful, historic San Francisco office sits in the shadow of the Golden Gate Bridge, it’s full of plants and radiates innovation and calm. We genuinely love working together. At lunch we talk about alignment and AI consciousness, we have surfboards in the office ready to use, we take walking meetings on the beach and hang out after work at the bar or climbing wall. We work really hard because we care deeply about what we do. Sauna is Wordware’s AI workspace for professionals. Think ‘Cursor for Knowledge Work’ and you’re halfway there. With explicit permission, it connects to tools like Gmail, Calendar, Slack, and thousands more, to gather the right context to move your work forward. It learns who you are, drafts and refines your documents, presentations, and datasets, researches across the web and your org’s internal knowledge, summarizes long threads to cut through the noise, proposes next steps, even acts on your behalf when enabled. You can work with Sauna live, side-by-side, or schedule jobs to run automatically in the background, with clear permissions and easy off-switches. Sauna brings the power of AI Agents to all professionals.

Respan (formerly Keywords AI) gives teams a unified control plane to trace and evaluate agent behavior without guesswork, automatically surface issues, and fix what breaks faster. Respan connects production observability, automated and human-in-the-loop evaluations, and an adaptive AI gateway to close the loop between detection, decision, and action - so agents improve continuously in production. Respan is trusted by 100+ AI startups and enterprise teams. Today, the platform process 1B+ logs and 2T+ tokens every month, supporting more than 6.5M end users.

Zep assembles the right context from chat history, business data, and user behavior so agents are personalized, accurate, and fast. Our open source project Graphiti hit 20k GitHub stars in under 12 months. Sub-200ms retrieval, SOC 2 Type 2/HIPAA certified, used by teams from startups to Fortune 500s.

Decipher AI generates your E2E tests, maintains them as you ship, and catches issues before customers do. Plus, get alerted when users hit live bugs. Used by the fastest shipping companies including Bilt, Arize, and Vial.

Ocular AI is the data annotation engine for Generative AI, Computer Vision, and Enterprise AI models. We help you transform unstructured, multi-modal data into golden datasets to power generative AI, frontier models, and computer vision. Ocular Foundry is the most intuitive, data-centric, and fastest platform that lets you label, annotate, version, and deploy your data for training models. It also orchestrates your annotation jobs, improving collaboration with members and annotators. With Ocular Bolt, shift from humans in the loop to experts in the loop to supercharge your data labeling and annotation projects. Our global expert workforce ensures fast, accurate results—no matter the scale or complexity of your data. Companies spend huge amounts on training data, but Foundry and Bolt are AI-native tools that lower costs, reduce manual effort, and accelerate high-quality data collection. We’re replacing outdated, clunky, and expensive data software!

Momentic is the modern alternative to Selenium, Cypress, and Playwright. We help software companies ship faster with reliable end-to-end tests that write themselves. World-class engineering teams like Notion, Quora, Bilt, Webflow, and Retool trust Momentic to uphold their quality bar. Learn more at momentic.ai

Greptile reviews pull requests with full context of the codebase. Top YC companies like PostHog, Raycast, Vouch, Podium, and YC's own internal software team use Greptile to review millions of changes every week. When companies start using Greptile, they catch more bugs and merge PRs 4x faster, on average Greptile can be used via the cloud, or be hosted 100% on your cloud in an air-gapped VPC.

We're building AI-native core tools & agent-driven workflows for frontend chip design. Today, Silimate is helping Fortune 500s and chip unicorns create & iterate to correct, optimized designs 40x faster. Our goal is to enable autonomous spec-to-design for silicon.

You want better search, not the burden of Elasticsearch. ParadeDB is the modern Elastic alternative built as a Postgres extension.

Fast Apply - Edit Files Faster - 10,500 tok/sec WarpGrep - Fast Context - 5x faster agentic code search subagent. eliminates context rot Glance- Videos of AI testing your PR, embedded in GitHub

Waldium is an AI-driven platform for researching, writing, and publishing technical knowledge in formats that both humans and AIs can understand. We help developers create technical guides, resources and tutorials — structured, durable knowledge that AIs can learn from, cite, and build upon.

Corgea is an autonomous application security platform that finds and validates vulnerabilities, then generates safe code fixes developers can apply in their existing workflow. In production customers like Zapier and Yageo, see ~20% more true positives and ~90% fewer false positives (vs their prior tooling), reducing triage and speeding remediation without adding headcount.

Use your favorite JetBrains IDE without compromising on AI. Sweep is the best autocomplete and agent in JetBrains: https://plugins.jetbrains.com/plugin/26860-sweep-ai

Artie is software that streams data from databases to data warehouses in real-time. Today, most companies run their ETL process every few hours or overnight, so their data warehouse is always out of date; with Artie, the warehouse always has live production data.

Omnistrate is a cloud platform to SaaS-ify your docker image in minutes instead of years. Let’s say you have an open-source software, and you want to monetize your invention by building a multi-cloud SaaS solution. You can either spend years doing it yourself or use Omnistrate to do it in no time. Get started today by simply importing your existing docker-compose.

Traditional automation software is slow and expensive, Automat is 10X faster and 1/10th the price. It lets operations teams automate using video and natural language. 🧐 The problem: Traditional Robotic Process Automation is slow and expensive. 💡 Our Solution: Automat makes it 10X cheaper and faster to build any robotic process automation using natural language on any operating system We’re solving this by creating a platform that enables robotics process automation for Chrome using large language models and computer vision. Currently our customers send us descriptions or videos of the processes they’d like us to automate and we use our internal tooling to quickly build out those automations.

Companies struggle to customize their generative AI models by taking advantage of their existing customer and enterprise data, in real-time. Chima solves for this through a sleek, interoperable layer before the standard generative AI models are applied.

LiteLLM is an open-source LLM Gateway with 18K+ stars on GitHub and trusted by companies like Rocket Money, Samsara, Lemonade, and Adobe. LiteLLM provides an open source Python SDK and Python FastAPI Server that allows calling 100+ LLM APIs (Bedrock, Azure, OpenAI, VertexAI, Cohere, Anthropic) in the OpenAI format We have raised a $1.6M seed round from Y Combinator, Gravity Fund and Pioneer Fund

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.