API Startups funded by Y Combinator (YC) 2025

The world’s largest omnichannel communications platform. Bird CRM powers communication between businesses and their customers — across any channel, always with the right context, and on every corner of the planet. Its products and solutions are the foundational building blocks to business communications across preferred channels, like SMS, Voice, WhatsApp, WeChat, Messenger, Email and more. Founded in 2011, Bird connects to billions of devices and is trusted by nearly 20,000 customers worldwide. Headquartered in Amsterdam, Bird operates across nine global hubs — including Singapore, Dublin, Shanghai, Sydney, London, Bogota and Asuncion — and is proud to be a “Work Anywhere” company. Its team of 500 employees represent more than 55 nationalities.

Checkr builds people infrastructure for the future of work. And we believe everyone should have a fair chance to work. That's why we've designed a faster—and fairer—way to screen job seekers. For more information on our mission and products, visit https://checkr.com.

Agentic Fabriq is the single control plane for data permissioning throughout your entire organization across your AI and employees. Through Fabriq, any employee can tap into AI/agents with exactly the data and tools they're cleared to use by an admin. Fabriq can be used internally with employees or externally for customers while handling the auth + integrations + permissions securely for you.

Parse lets developers build APIs for any website. Unlike traditional scraping tools that rely on slow, expensive headless browsers, Parse reverse-engineers websites' underlying network requests and generates API endpoints automatically. This makes Parse 10-100x faster and cheaper than browser automation,.

S2 is a serverless datastore for real-time, streaming data. The more we worked on data systems, the more we felt like there was a missing building block. The seamless experience of object storage simply did not exist for durable streams – so we set out to fix that! S2 reimagines streams as an unlimited and access-controlled web resource. Like if Kafka and S3 had a baby. - Building agents? Use granular streams to persist context in real time, make workflows auditable, and coordinate between agents. - Publishing fast-moving data? Streams support high fanout and can be accessed directly over the internet, so they are a great fit for broadcasting real-time feeds. - Sandboxing? Emit to per-instance streams, and read history or live events just as easily. - Local-first and multiplayer experiences? Propagate updates reliably and efficiently. Stop dealing with clusters, and start streaming.

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

Klavis AI is Open source MCP integration platform that let AI agents use tools reliably at any scale. Our API provides hosted, secure MCP servers, eliminating auth management and client-side code. Co-founder Xiangkai Zeng co-authored the Gemini paper and pioneered the tool calling infrastructure for Gemini. https://www.klavis.ai/

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.

ReJot is building Fragno to let API companies go from simply exposing an API to offering drop-in integrations that work out of the box. Fragno is an open‑source framework for packaging backend endpoints, data storage patterns, and frontend utilities into reusable building blocks. API providers ship full integrations, not just low‑level SDKs and docs. Customers configure rather than write code, so integrations are both much faster to launch and far more consistent across customers.

BlindPay is a stablecoin API that enables companies to send and receive money worldwide using fiat money, stablecoins and multiple blockchains. We handle all the complex compliance and regulatory requirements, so companies can focus on their core business.

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

Surge is Stripe for telephony. Our team has experience building telephony software at billion dollar scale. Because of increased regulation, Twilio and other SMS APIs take weeks to onboard new customers, but we can get startups onboarded same day. Surge wins by enabling easy carrier registration, better support, and higher level APIs and no code UI components to make implementation easier for startups and developers.

Ultralight is a GPU-accelerated toolkit to embed modern HTML in games and native apps. Available for C and C++ on Windows, macOS, Linux, Xbox, PlayStation, ARM64 devices, and more. Developed in collaboration with leading game studios, built GPU-first on a new, lightweight fork of WebKit.

If you’re a founder and feel like you—or your exec team—are too far removed from the customer, Overstand is here to help. We’re the platform (and API) for your customer communications, turning Slack, emails, WhatsApp, call recordings, and more into actionable insights. For example, we can help you discover feature requests hidden in customer emails, spot upsell opportunities from a casual Slack message, or identify a critical support issue buried in a call transcript -- all without having to depend on others in your company to fill out a form or write meeting notes. Get back to Founder Mode by spotting trends, uncovering growth opportunities, and staying deeply connected to your customers. Overstand makes it easy to understand where you’re needed most and take action that drives impact. 🚀

Automatically organizes your team's emails and meeting notes. Find anything in seconds, get intelligent email drafts, and reclaim hours every day.

Panora automates PO entry for distributors, manufacturers and wholesalers. Stop wrong shipments, block duplicates, reclaim ~80% of your order-entry time.

Integuru turns any website into a reliable, real-time, and low-latency API. No RPA required. Our services include authentication management and integration maintenance.

Downlink is a platform that continuously improves your AI. Boost rate limits, slash latency, and raise accuracy.All through one simple API.

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.

nCompass is a platform for acceleration and hosting of open-source and custom AI models. We provide low-latency AI deployment without rate-limiting you. All with just one line of code.

Precip uses AI to make hyperlocal weather observations. We’re started with the most important dimension of weather: rain. For example, one of our customers uses Precip daily to make sure their heavy trucks won’t get stuck in muddy fields. Our highly rated mobile app is the best way to see rain and snow totals anywhere.

Generate AI agents with plain English, edit visually, customize with code in your own IDE. Currently automating millions of tasks across support, sales, finance and more for companies like eToro, Payoneer and JustEat.

The first version of RecipeUI was a viral project at Robinhood that reached 100% adoption from all engineering and QA teams. When an API broke, anyone from Frontend to QA to PMs could debug without relying on backend engineers

Inconvo is an all-in-one platform for building and releasing ChatGPT apps. We save companies months of development time by handling connection to SQL databases, AI query guardrails and user authentication.

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.

Smobi is the AI-powered platform for branded, interactive business messaging, starting with RCS. We help businesses send rich, personalized messages that drive engagement, build trust, and create real conversations.

Oversteer is building browser agents to automate web tasks and turn them into reusable, deterministic APIs. You can integrate the API into any system and automate/integrate any website or portal.

Sohar Health is an AI-driven front-end RCM solution that transforms insurance verification processes for healthcare providers, enabling faster patient conversions and reducing administrative workloads. With a 95% automation rate, our API-first platform seamlessly integrates into existing workflows to provide real-time claim accuracy and eligibility checks. Key performance metrics showcase the power of our technology: Median latency of just 6 seconds, ensuring real-time eligibility; over 90% of checks returned within 30 seconds for increased patient conversion; 96% accuracy in identifying and verifying benefits details; Industry-leading 99% accuracy for eligibility determination; >90% carve-out detection rate, mitigating surprise billing risks; a 60% success rate with our Insurance Discovery API, helping identify coverage for self-pay patients. Our customers include outpatient clinics, specialty practices, and digital health platforms looking to streamline front-end claim management. By reducing errors and maximizing clean claim submissions, Sohar Health empowers healthcare organizations to convert and retain more patients, reduce operating costs, and increase their top-line revenue.

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

Terminal is Plaid for telematics data in commercial trucking. Companies building next generation insurance products, financial services and fleet software for trucking use our Universal API to access GPS data, speeding data and vehicle stats. Raghav (CEO) and Connor (CTO) led product and engineering at a series b-funded neobank where they spent 2.5 years integrating middleware APIs like Plaid & Stripe. Before that, Connor spent 3 years building software for his family-owned logistics company which was acquired by a private equity firm. Raghav’s family is in fleet operations and owns an HVAC company in San Francisco where they operate a fleet of 13 commercial vehicles.

Edit Files at 10500+ tok/sec. The other models you need to build the best coding agents that are fast, reliable, and cheap.

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.

SuperAPI is a programmable API gateway that makes all your fetch APIs cacheable, reducing the response time 10x. Our customers use SuperAPI to cache their critical APIs without spending 6-9 months rewriting their code.

SpecCheck is an all-in-one solution that provides accurate prescription eyewear ordering and tracking, seamless billing, and streamlined communication between patients, eye doctors, and their lab partners. SpecCheck’s users work more efficiently and make fewer costly errors, increasing productivity and improving their overall workflow.

Mercoa helps AP and Spend management platforms drive more virtual card volume from their BillPay customers. Our agent identifies card-eligible invoices and securely pays them through supplier portals or payment links.

Resend is the new email API for developers. It's designed for you to build, test, and send transactional emails at scale. If you're using Sendgrid, AWS SES, or Postmark, come talk to us.

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.

Escape fits right into your modern stack and helps teams secure modern applications— Document all your APIs & front-end applications in minutes and discover vulnerabilities even at a business logic level with our proprietary AI-powered algorithm.

PoplarML lets you deploy any machine learning model to a fleet of GPUs as a ready-to-use and scalable API endpoint with one command.

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.

Propexo lets engineers build, test, and launch CRE software integrations in days, not months. We modernize the developer experience for our customers, providing clear documentation and robust infrastructure to support the needs of property owners, property managers, & proptechs.

Orchestrate custom integrations, workflows & agents in hours, not months. Take control of your integration strategy and breathe easy with maintenance on AI Autopilot. For Product Teams: Build better integration libraries. Build a feature-rich integration library, for your users to enjoy. Offer out-of-the-box integrations that work for you and your customers. Embedded IPaaS typically locks you into connector or endpoint limitations. Versori gives you to tools for limitless customisation. Proactive, self healing agents, scan your connected apps for endpoint or schema changes. You get alerted, Versori AI fixes the change. Embed Versori built integrations into your app with the Versori SDK. Flexible to your development approach with advanced user management. For Operations Teams: Get your internal systems speaking the same language. Deliver integrations for new software in days, not months—so you can start unlocking value immediately. Versori’s speed to value reduces typical deployment fees by half—or more. Low code for speed. Full code for control. No more limits from inflexible integration platforms. For GTM & Sales Teams: Say yes to any prospect's integration request. Stop bouncing between teams to get integrations built. With Versori, Sales can go straight to yes. No more escalations or delays. Versori offer fully managed custom-builds, so your customers get exactly what they need, without compromise.

Anchor provides APIs, dashboard and tools that help developers easily embed and build banking products. This includes APIs for creating bank accounts, funds transfers, savings products, issuing cards and offering loans. We also provide regulatory coverage and continuous compliance support to our partners.

A personal cloud storage platform that's so good, it'll replace Finder / File Explorer on your desktop. Find anything with multi-modal, natural language search. Browse with a lightning fast interface that feels just like native. Organize, tag, view, edit, share, and more.

Typeless is an AI messaging API designed to facilitate communication for businesses and professionals. Our API generates smart, context-aware response suggestions to enhance messaging platforms in a variety of industries, from real estate to customer support. For example, a real estate platform can use Typeless to automate responses for scheduling property viewings, answering client inquiries, and handling follow-ups. Similarly, a customer service platform can enable agents to respond faster with personalized, AI-driven suggestions for customer questions and issues. You can download our demo messaging app built with the TypeLess API on the app store: https://apps.apple.com/us/app/typeless-ai-messenger/id6478489620

Axle is Plaid for insurance - a universal API for insurance data. With Axle, companies can instantly verify insurance and monitor ongoing coverage, helping them reduce operational cost while creating a frictionless experience for users. Axle is backed by leading investors including Y Combinator and Gradient Ventures, Google's AI-focused venture fund, and angels from industry leaders like Plaid and Cox Automotive.

MovingLake is Fivetran for event-driven architectures. Companies such as Casai use our product to obtain orders and price changes in real time.

Assign Tasks by Call, E-mail, or Message — Your Assistant will Handle the Rest! https://unify.ai ✨

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.