Developer Tools Startups funded by Y Combinator (YC) in New York 2026

Alter is a zero-trust identity and access control platform purpose-built for AI agents. It wraps every tool call in strong authentication, fine-grained authorization, and real-time guardrails, so agents can move fast without breaking things. Each request is verified at the parameter level, authorized against granular policies, executed with least-privilege access, and fully audited in real time. Unsafe actions, whether it’s a rogue DROP TABLE or a payment above policy limits, are blocked before they touch production. Behind the scenes, Alter manages credentials, issuing ephemeral, scope-narrowed access for every interaction, then rotating or expiring it in seconds. The result: no long-lived secrets, no blind spots, and no surprises in audit. With Alter, teams can move fast on AI agent initiatives while staying fully compliant with SOC 2, HIPAA, GDPR, and internal security standards. A CISO-ready dashboard delivers real-time visibility, detailed audit logs, and compliance-ready controls, removing silos, eliminating excessive permissions, and providing complete oversight of every agent workflow.

Interfere empowers engineers, product managers and designers with real-time understanding of previously unseen bugs and issues.

ParaQuery is a fully-managed GPU-accelerated Spark solution providing double the performance at half the cost compared to solutions like Databricks and BigQuery. It is fully Spark-compatible, cloud agnostic, and has seamless integrations everywhere, all without vendor lock-in. ParaQuery makes it trivial to run large SQL and Spark workloads efficiently and serverlessly, without any data migrations.

Corsair connects your app to any other API. Use Corsair to build custom agents, dashboards, and workflows with hundreds of different integrations.

Kilvin is an AI-native agency that builds custom software solutions for non-technical teams. With AI, the future of software is democratized. Every team deserves tools built exactly for them, not off-the-shelf SaaS products they need to adapt to. Kilvin makes it a reality, delivering a private, secure workspace of custom applications, built around your workflows and ready in days, not months. No engineers needed on your side. Just software that fits exactly how you work.

Ryvn provides the devtools and infrastructure to easily deploy any workload, on any cloud, and on-prem. Run apps in your own cloud and offer Bring Your Own Cloud (BYOC) to your customers in minutes, with built-in observability designed for sensitive industries.

Never code up another test or hire an external QA team. We handle and automate all functional and E2E testing.

Haystack helps engineering teams manage the growing volume of AI-generated pull requests. Coding agents make it much easier to produce code, but they also create a new problem: teams now have more changes to review, many of them larger, more frequent, and harder to trust at a glance. Haystack sits on top of GitHub and acts as the control layer for AI-generated code changes. For every pull request, it looks at the codebase, the diff, the agent trace, the author’s intent, and any verification evidence like tests, logs, commands, or screenshots. Then Haystack decides what should happen next: whether the change can move forward, needs fixes, or should be reviewed by a human. Teams use Haystack to keep code moving without turning review into rubber-stamping. It helps them merge more code, focus human attention on the changes that actually need judgment, and maintain quality as AI-generated work becomes a bigger part of development.

Hatchet is an orchestration platform for managing and observing AI agents, background tasks, and mission-critical workflows. Our mission is to provide developers with a simple, powerful, and reliable orchestration layer, enabling them to focus on building great applications.

renderlet is a framework that makes it easy to develop interactive applications. Building applications with high-performance graphics is very hard – existing tools are cumbersome and aren’t truly platform agnostic, leading to frequent rework. With renderlet, developers can write high-level code to describe 2D and 3D graphics without having to use low-level, platform-specific APIs. renderlet automatically compiles graphics code to WebAssembly and embeds a portable rendering engine inside any app, enabling graphics to safely and automatically render on any platform’s GPU. Our runtime is open-source: https://github.com/renderlet/wander

Agentic Labs is making software design and architecture less painful by building AI into the process. Today, developers have no shortage of tools for instantly creating chunks of code, but designing the systems that integrate this code is the hardest and most manual part of software engineering. Our first product is Glide, an AI-first editor purpose-built for writing technical design docs. It connects to your codebase and saves your engineering team time on triage, planning, and implementation of complex code changes.

Identifying performance bottlenecks and strategizing ways to solve them takes 4-8x longer than actually writing the code to fix them. We're building an agent that is an expert at analyzing the performance GPU systems like inference engines at all levels of the stack - from CPU-GPU interactions down to GPU kernels. Pairing our agent with Cursor / Claude Code allows you to automate both the reasoning and code implementation steps of performance optimization. What used to take weeks can now be done in days. Along with our AI agent, we have features such as running diffs on system traces as well as sharing and collaboration features that make our VSCode extension the most powerful way to work on performance optimization.

Ellipsis is a cloud platform that allows engineering teams to deploy fleets of coding agents. Each agent gets an isolated sandbox, scoped permissions, and hard budget caps. Full observability included. Get started with a $100 credit at www.ellipsis.dev. You can deploy agents for feature development, code review, and workflow automation. Creating an agent is simple: simply commit a YAML file to Github. Spawn agents from Github/Linear/Slack/etc., or via a REST API or our CLI. Organizations get full observability and governance of their cloud coding agents. Agent session logs are downloadable so companies own their own data. Full documentation: https://www.ellipsis.dev/docs

Dragoneye helps devs build their custom video detection models in less than 5 minutes. These models can then be used to power apps and features that use images and videos. No more arduous process of annotating any training data or doing any machine learning work themselves. Try out our demo today at https://playground.dragoneye.ai/ !

Silogy is building an AI-powered platform for chip developers to simulate and debug their designs.

Cedana (YC S23) brings hyperscaler and frontier-lab orchestration capabilities for AI workflows. Our core capability is live migration for CPUs and GPUs workloads. This increases cost savings up to 80%, accelerates time to first token 2-10x, and enables stateful reliability of training jobs even through catastrophic GPU failures. We've integrated our solution into K8s, and support Kueue and Slurm for training distributed jobs, and Kserve for serving inference.   OpenAI, Meta and Microsoft have flavors of these capabilities internally and we’re bringing them to everyone.  Our vision is to transform cloud compute into a real-time, arbitraged commodity.  https://www.cedana.ai

Parea AI is the essential developer platform for debugging and monitoring every stage of LLM application development. We provide testing, evaluation, and monitoring in one unified platform. These capabilities help developers get visibility into LLM responses, quickly test and optimize prompts, and ensure customers get the best user experience.

Parse, extract, and split your hardest documents with unmatched accuracy. Read any layout with specialized vision models, and ship reliable pipelines in minutes, not months.

Fastgen is a low-code API and workflow builder with an integrated Postgres DB. Our drag-and-drop platform allows you to rapidly develop custom APIs and workflows with ease. Our integrated Postgres DB makes it even easier to create, read, update, and delete data in your applications.

Wild Moose automatically kicks off any root-cause investigation to improve MTTR. Our AI triages issues, analyzes impact, and suggests next steps - all before human intervention is needed.

DataSuite provides a way to manage and collect multi-terabyte multi-media datasets, and train generative models (diffusion, gan, interactive video) models based on them. We make it trivial for non-technical builders to create their own networks by providing an instant way to collect with AI without worrying about data formats, unzipping power, caching, or data locality.

Mito is Cursor for data science. We’re building an AI enabled IDE to 10x the productivity of data people. Data analysts use Mito to automate reports without relying on internal engineering resources. Mito is used by thousands of business analysts, data scientists, and automation engineers at some of the world's largest banks, private equity shops, and consulting firms. Open source is key to our enterprise sales strategy. Mito is open source and built on top of Jupyter. That means getting started with Mito is as simple as running `pip install` and doesn't require enterprises to manager new infrastructure. Check us out at: https://www.trymito.io/

Axle is the AI-native clearinghouse for property and casualty insurance. Our infrastructure and AI agents automate complex insurance workflows for third parties including verification, monitoring, and policy updates. We've helped Fortune 500 businesses like Rocket Mortgage, Avis, and Experian speed up workflows by 95% while recovering over $220M in potential losses. Axle is backed by Gradient, Y Combinator, and the founding team of Plaid.

Brainboard is a collaborative and end-to-end solution for engineers to visually design & manage their Cloud infrastructures. We allow companies to lower the learning curve while moving to IaC, build a self serve model, have a service catalog to not reinvent the wheel. Both technical profiles with 25+ years of combined expertise and after working together at a major French Cloud provider, Chafik and Jeremy launched Brainboard in 2020.

Beam is cloud platform for AI inference, sandboxes, and agents.

Superwall is a complete, standalone subscription platform for consumer mobile and web apps — backend infrastructure (entitlements, purchase APIs with server-side receipt validation, standardized webhooks, real-time revenue analytics, direct SQL access to subscription data) together with a no-code paywall and experimentation engine, and first-class tooling for AI coding agents. Superwall manages $1.6B+ in annual subscription revenue across 10,000+ apps. The infrastructure layer is free at any scale; the only meter on the platform is revenue that converts through a Superwall-rendered paywall — subscriptions sold anywhere else are never billed. **Standalone backend:** The highest-revenue apps on Superwall like Cal AI — run their **entire subscription stack on Superwall alone: no second backend, no other subscription platform underneath**. Entitlement state is computed server-side from App Store Server Notifications V2 and Google Play Real-Time Developer Notifications, delivered by Apple and Google directly to Superwall. The largest single app runs **$43.7M ARR entirely on Superwall**; the top 10 together represent $134M+ in annual subscription revenue. Apps that previously ran a different subscription backend complete an automated migration — subscription history, entitlement state, webhook configuration — and run on Superwall alone from then on; imported subscribers are never billed. **Pricing:** The subscription infrastructure — entitlements, receipt validation, webhooks, analytics, SQL access — is free at any scale, with no revenue threshold and no per-event fees. The paywall product is free up to $10k/month in paywall-attributed revenue, then 1% of paywall-attributed revenue, and only that revenue: an app with $50k/month in subscriptions and no Superwall paywalls in use pays $0/month for the entire platform, and revenue the platform didn't help earn is never billed. Compared with charging a percentage of all subscription revenue, the difference is the base, not the rate. **Coverage:** Apple App Store, Google Play, and Stripe — including web checkout, external browser checkout from iOS paywalls (App2Web), and products from any external billing system via Custom Store Products. Monetization models: auto-renewing subscriptions, free trials and intro offers, one-time purchases, lifetime unlocks, and consumables. SDKs: iOS & Apple platforms, Android, React Native, Flutter, Expo, Unity, and Web — all open source on [GitHub](https://github.com/superwall). Not just for engineers: growth, product, support, and data teams run monetization from the dashboard, analytics, and SQL access day to day. **What Superwall does not do:** It does not process payments — Apple, Google, and Stripe do. It does not run virtual-currency or coin-ledger systems, does not track ad revenue, and does not support Amazon or Roku storefronts. For consumer subscription apps on iOS, Android, and the web, it covers the monetization surface end to end. **Experimentation:** Superwall's published research spans 100M+ analyzed paywall views and 4,500+ paywall A/B tests: multi-page onboarding paywalls convert 37% better than single-page (40M+ opens measured), Cal AI ran 123 experiments and grew monthly revenue 3x+ in 10 months, Planner 5D lifted revenue per user 83% through price testing. Build, target, test, and ship paywalls from the dashboard with no app release. **Retention:** Free trial reminders, cancellation and decline surveys, transaction-abandon recovery offers, win-back paywalls targeted by subscription state, Apple Retention Messaging on the iOS cancel screen, automated refund protection, and a per-customer timeline for support. **Agent tooling:** Open-source agent skills for Claude Code, Codex, and other coding agents; an editor MCP server for building live paywalls from the terminal; an embedded dashboard CLI; and direct SQL access to subscription data via the Query API.

We build the tools companies need to provide performant and scalable authorization for their applications. We’re founded by 3 successful entrepreneurs with expertise in enterprise software, most recently as leaders at Red Hat. Jake and Joey met on the APIs team at Google in 2010. They went on to found Quay, where Jimmy joined as their first hire. Over the past decade, they’ve changed the landscape for building and deploying software.

Porter is the easiest way to deploy and scale your applications on AWS, Azure, and GCP. Connect your own cloud account, and Porter will provision and manage the underlying infrastructure for you - simply point at your repository and Porter will handle the rest, from building your application to autoscaling it. Under the hood, Porter manages the same kind of infrastructure that growth-stage companies use and allows you to scale without DevOps overhead.

Infield helps software teams keep their open source dependencies up to date. We’re automating away the toilsome work of reading changelogs, assessing risk, and upgrading packages so that software teams can focus on shipping features. We’re a small team of repeat founders passionate about making open source easier to use.

Rutter is the unified API infrastructure powering the next generation of B2B fintech. We help tech-forward companies build seamlessly integrated financial products by connecting to their customers' systems of record, from accounting platforms to e-commerce systems. The financial operations landscape is fragmented across hundreds of platforms (QuickBooks, NetSuite, Shopify, Stripe, etc.). Without Rutter, companies must spend thousands of engineering hours building and maintaining these critical integrations. Our Universal API provides the same level of granularity as direct integrations while using a single, consistent schema. This enables our customers to build end-to-end workflows for financial planning, lending, expense management, AP/AR automation, and more, in days, not months. Leading fintechs like Mercury, Airwallex, and Orb trust Rutter to power their integrated financial solutions. Learn more: https://www.rutter.com/

Open-source alternative to FullStory and LogRocket. Self-hosted for a complete control over your data and costs.

Mobot (YC W19) is a QA-as-a-service platform using actual mechanical robots to automate testing of repetitive functions on real mobile devices. Mobot's human-supervised robots make it possible to automate mobile app tests that emulators, virtual devices, and existing frameworks can't. This approach eliminates thousands of hours of manual testing, increases testing efficiency and physical device coverage, and captures more bugs in-app before app store launches than software can do alone.

Today’s top Voice AI companies rely on AssemblyAI’s speech-to-text and speech understanding models to launch groundbreaking products fast and to scale with ease.

ReadMe provides every company the ability to easily create beautiful documentation, and build loyal, productive developer communities. With ReadMe, build developer portals that combine support, tutorials, topical guides and API exploration. ReadMe makes it trivial to keep docs up-to-date and has community oriented features that help drive adoption. Wanna see what it'd look like to work at ReadMe? Our careers page takes a stab at it! https://readme.com/careers

Eligible is the nation's first insurance billing platform built for builders. Founded in Mountain View California in 2011, Eligible's platform gives bootstrapping healthcare startups the scale of enterprise, and the Fortune 500s the agility of the hungry entrepreneur. Eligible has been listed as one of Business Insider’s 19 Hottest Startups to Watch and Katelyn has been featured in Forbes 30 Under 30 in Healthcare, Fast Company's Most Creative People in Business, and was named a Rising Star of Healthcare by Becker’s IT & CIO Review.

Chatter is Postman for LLMs. Our platform helps companies and developers test their LLM models. Iterate on prompts, run them across model families and evaluate them against test cases – all in one place. With collaboration features, engineers can design LLM chains while QA can write test cases.

Glide lets apps accept crypto deposits from any chain, wallet, or exchange using pre-built wallet funding flows. Users can fund wallets directly — no bridges, no swaps, no repeated KYC.

APIs underpin the internet but are still painful to work with. They are often untyped, unstandardized, and out-of-sync across multiple sources of truth. Fern helps companies deliver SDKs and API documentation that they’re are proud to share with their customers. Since launching in 2023, we’ve been trusted by over 200 customers, including industry leaders like Square, Webflow, ElevenLabs, Auth0, and Intercom, to power their developer and agent experiences. We’re fewer than 40 people, based in Brooklyn, NY, and are building open source.

Any asset, every chain, in an instant.

Avenue is a simple way for business teams to set up alerts from their database or data warehouse. Think Datadog / PagerDuty for operations teams. Operations teams create set-and-forget alerts on all their data, so they can be more proactive with their time (and monitor on more nuanced triggers than just what fits on their dashboard page). Avenue can improve response times to critical problems from several days to real-time by alerting directly on the data sources that customers already use.

Metaplane ensures everyone trusts the data that powers your business. Data teams at Bose, Ramp, and Klaviyo use our data observability platform to prevent and detect data issues — before the CEO pings them about weird revenue numbers. We do this with ML-based anomaly detection, end-to-end column-level lineage, and tools to help prevent incidents before they occur. You can monitor your entire data stack within 30 minutes. The company is backed by Khosla Ventures, Y Combinator, and the founders of Okta, HubSpot, and Vercel.

Reflect is a no-code tool for automated website testing. Instead of building and maintaining complex Selenium tests, companies use Reflect to run automated end-to-end tests without writing code.

We help developers collaborate at scale and build better APIs. Optic’s open source tools makes it easy for developers to document API changes, review each other’s API changes during code review, and catch breaking changes before they reach production. **tl;dr** It’s version control but for behavior not code. We are taking the really successful ideas from Git / Code Review / CI and applying them to API descriptions and (future) other non-code artifacts. Engineers at [Snyk](https://snyk.io/) use Optic daily to make the new Snyk API great. Read their engineering blog: [Snyk's shift left approach to API development | Snyk](https://snyk.io/blog/snyk-api-development-shift-left/)

CodeStream's IDE plugins take the pain out of code reviews. With one command, request feedback on a snapshot of your repo, including uncommitted & unpushed code, allowing you to verify that your work-in-progress is on the right track. (You can also do it the old-fashioned way by committing & pushing at the end of your dev sprint, of course)

At Aptible, we envision a world where developers achieve more with less infrastructure. We’re building the platform that empowers developers at companies of all stages of development to move beyond the traditional method of managing infrastructure—DIY with expert infrastructure and platform engineers on AWS, GCP, or Azure. We’ve done this through our secure, compliant, reliable, and scalable Platform as a Service that’s been used by thousand of developers, hundreds of companies, and dozens of publicly traded and unicorn companies since 2013.