API Startups funded by Y Combinator (YC) in the San Francisco Bay Area 2024

April 2024

Browse 35 of the top API startups funded by Y Combinator. Headquartered in the San Francisco Bay Area, these are some of the hottest and fastest-growing startups.

We also have a Startup Directory where you can search through over 5,000 companies.

  • Checkr
    Checkr (s2014)Active • 1,200 employees • San Francisco, CA, USA
    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 http://checkr.com.
    artificial-intelligence
    compliance
    hr-tech
    api
    enterprise-software
  • Modern Treasury
    Modern Treasury (s2018)Active • 160 employees • San Francisco, CA, USA
    Modern Treasury offers tools that automate the full cycle of money movement—from payment initiation, through approvals, to reconciliation—and are accessible through web application or API.
    fintech
    api
  • Mux
    Mux (w2016)Active • 140 employees • San Francisco, CA, USA
    Mux is an API-first video platform designed by experts to make world-class video streaming and analytics possible for every development team. Self-optimizing videos take the guesswork out of encodings, delivery, and renditions. Mux makes your video look beautiful on every device, every time. We offer two products, Mux Video and Mux Data. Mux Video is a simple API to advanced video streaming. Powered by data and designed by video experts, Mux Video makes beautiful video possible for every development team. Post a video or live stream with a single API call, and watch it within seconds. Mux Video handles the encoding, storage, and delivery. QoE and performance analytics provided by Mux Data is included by default for every Mux video stream.This real-time data is used to create the right renditions for every device and title, resulting in greater reliability and better viewer experiences. Mux Data is a Quality of Experience analytics platform that measures the performance metrics that actually matter to viewers: rebuffering, startup time, video quality, and errors. Our intuitive dashboard quickly gives users the insight to find issues and make improvements through features like A/B testing, industry-wide scores, alerts, and detailed information about every single video view. The product works out of the box on HTML5, iOS, Android, and major OTT platforms. All data is available via exports and APIs, making it easy to integrate Mux Data into other systems.
    developer-tools
    video
    api
  • Alpaca
    Alpaca (w2019)Active • 150 employees • San Mateo, CA, USA
    Alpaca is an API infrastructure and licensed financial services company that allows developers and businesses to offer stock and crypto investing to their end-customers. We work with more than 100 companies across the globe to enable their investing products, and our mission is to provide financial services to everyone on the planet. Alpaca’s globally distributed team consists of developers, traders, and brokerage business specialists and backed by a group of well-capitalized investors including Portage Ventures, Spark Capital, Tribe Capital, Unbound, Social Leverage, Horizons Ventures, Y Combinator as well as highly experienced industry angel investors and founders. We are also very tech-enthusiastic with notable track records in open-source and startup communities.
    developer-tools
    fintech
    api
    investing
    infrastructure
  • Treasury Prime
    Treasury Prime (w2018)Active • 100 employees • San Francisco, CA, USA
    Founded in 2017, Treasury Prime is an embedded banking software platform connecting enterprise companies to a vast marketplace of banks and product partners to launch next-gen payment ecosystems on their platform. Our banking API offers the quickest, most secure way for fintechs and banks to partner, integrate and build modern financial products and increase revenue streams. We power enterprise-class embedded banking solutions for a range of complex services including money transfer, risk mitigation and integration with bank infrastructure. It's these leading-edge capabilities that helped the company to win Best Banking-as-a-Service Platform from Tearsheet in 2021 and 2022. The company was also named to CB Insights’ annual 2021 Fintech 250 list.
    banking-as-a-service
    fintech
    b2b
    api
  • Deepgram
    Deepgram (w2016)Active • 115 employees • San Francisco, CA, USA
    Deepgram is a foundational AI company on a mission to understand human language. We give any developer access to the most advanced speech AI transcription and understanding with just an API call. Our models deliver the fastest, most accurate transcription alongside contextual features like summarization, sentiment analysis, and topic detection. Beyond that, developers can: 🔊 Process live-streaming or pre-recorded audio 🌎 Transcribe in dozens of languages ⚙️ Train custom models for unique use cases 🔑 Access deep NLU with a unified API 💻 Build in any programming language with our SDKs ✅ Deploy on-prem or on DG’s managed cloud 📈 Get scalable GPU infra for training and inference Deepgram is a proud NVIDIA partner and Y Combinator company, and we recently completed a $72M Series B to define the future of AI Speech Understanding, making us the most-funded speech AI company at its stage.
    ai-enhanced-learning
    artificial-intelligence
    api
  • Veryfi, Inc.
    Veryfi, Inc. (w2017)Active • 60 employees • San Mateo, CA, USA
    Veryfi is a Data Transformation Platform turning Documents into Data in Seconds with Accuracy & Speed Surpassing Humans. Veryfi gives you a fully integrated suite of data transformation products for you to securely capture, extract and transform bills, receipts and invoices into structured data for use in your app, website or backoffice. To learn more https://www.veryfi.com/ ITS TIME TO BUILD Veryfi's developer friendly toolkits enable superior products that automate Expense Management, AP/Bill Pay, Bookkeeping and provide consumer spend behavior in Market Research Invoices, Bills & POs 10 mins of data entry per invoice? No way! 5 seconds and it's done. Untap a goldmine of data down to line-items. Expense Receipts No more painful data entry for expense reimbursement. Bonus: comply with new data privacy regulations. FMCG/CPG Receipts Data is the new oil. Understand consumer spend across retail from SKUs in seconds. Hotel Folios Supercharge your travel & expense management product with a wealth of data minus the tedious data entry. W-2 Tax Form β Extract every drop of tax data from W2s in seconds. Including handwritten notes, checkboxes and multi-lines. Cards β Capture and extract data Credit Cards, Business Cards and Healthcare Insurance Cards in seconds. More: https://www.veryfi.com/
    artificial-intelligence
    machine-learning
    computer-vision
    api
  • Cosmic
    Cosmic (w2019)Active • 5 employees • San Francisco, CA, USA
    Cosmic is a headless CMS and API toolkit to help teams build modern apps faster, together. We provide a web dashboard to create content and API tools to deliver content into any website or app. Teams benefit from using Cosmic because it eliminates the need to build and maintain their own CMS infrastructure. Teams pay a monthly subscription fee for our hosted CMS and can focus on their application logic, creating great content, and enhancing user experiences.
    developer-tools
    api
  • Ultralight
    Ultralight (w2019)Active • San Francisco, CA, USA
    Effortlessly display modern web-content everywhere. Think of Java, but for web-content and JavaScript. Available for desktop apps, game consoles, embedded device displays, servers, and more.
    developer-tools
    hard-tech
    b2b
    gaming
    api
  • Velt
    Velt (w2022)Active • 10 employees • San Francisco, CA, USA
    Our mission is to make the web more collaborative. We're not just making collaboration faster—we're crafting it to be the best. Today we’re all using online platforms more than ever before - building, researching, learning, connecting etc. And we're not doing it alone. We're doing it together with other people and machines, turning the internet into the world's biggest team. Yet, the web was built for solo voyages. We saw a shift when platforms like Figma and Google Docs brought a multiplayer approach, breaking down walls and inspiring seamless teamwork. At Velt, we're taking it further. We're on a mission to infuse the magic of collaboration into the fabric of the web—one app at a time. We aim to erase the lines between online and offline co-working, crafting an environment where distance is irrelevant, and 'flow' is the norm. Right now, more than half of work hours are spent on coordination and communication—less on creating. With Velt, we're setting out to reverse these figures, reducing time spent on logistical issues by over 90%. Imagine what we can create when we spend less time talking about work and more time doing it! We're building a better web—a web for us, for our team, for everyone. Join us, and let's accelerate the future of web together 🚀 Our Products: - Velt Collaboration SDK (https://velt.dev/): JS SDK to add powerful collaboration experiences to your own product for your end-users. This helps you ship such experiences ridiculously fast, increase user growth and engagement. - Superflow (https://usesuperflow.com/): JS plugin to enable product, marketing and design teams to comment and collaborate directly on their websites. This helps them iterate and ship their products 10x faster. We’re a team of ex-Googlers. We've launched products like Augmented Reality in Google Search & Maps. Come build a better web with us 🚀
    developer-tools
    saas
    collaboration
    api
    remote-work
  • Quill
    Quill (w2020)Active • 5 employees • San Francisco, CA, USA
    React Library, API, and Management Toolkit, purpose built for customer-facing dashboards.
    saas
    analytics
    api
    data-visualization
  • Vital
    Vital (w2020)Active • 10 employees • London, UK
    Vital is an API for at-home health data that makes it easy for health tech companies to collect data from 100's of wearable devices and deliver at-home test kits to their users. Healthtech companies need lab data as well as wearable data, and we give them access to both through a single line of code.
    health-tech
    digital-health
    api
    health-&-wellness
  • Agave
    Agave (w2022)Active • 11 employees • San Francisco, CA, USA
    We build data infrastructure (APIs, financial automation) for construction, an unsexy-but-huge ($12T) industry. We help construction software companies integrate with the fragmented and old software that runs construction globally using our API. We help construction companies automate manual work in a no-code interface powered by our own API.
    saas
    construction
    b2b
    proptech
    api
  • Metlo
    Metlo (s2021)Active • 4 employees • San Francisco, CA, USA
    - Create an Inventory of all your API Endpoints. - Proactively test your APIs before they go into production. - Detect API attacks in real time.
    saas
    b2b
    security
    open-source
    api
  • Warrant
    Warrant (s2021)Active • 3 employees • Los Angeles, CA, USA
    Warrant is an open source authorization service that helps developers implement and enforce access control in their applications. Warrant serves as a dedicated, centralized platform for handling user authorization and access control so engineering teams can focus on building their core products.
    developer-tools
    b2b
    open-source
    api
  • Bytebot
    Bytebot (s2021)Active • 2 employees • San Francisco, CA, USA
    Bytebot simplifies and streamlines web tasks by translating natural language prompts into browser automation, including clicks, form filling, and data extraction. The platform and SDK enables users to develop robust, dynamic web automation scripts that adapt alongside changing web environments. Effortless to use and easy to integrate, Bytebot helps users boost their workflow efficiency and drive growth, all without the complexity.
    artificial-intelligence
    robotic-process-automation
    saas
    api
    ai-assistant
  • Convore
    Convore (w2022)Active • 4 employees • San Francisco, CA, USA
    Universal conversation API for developers
    artificial-intelligence
    developer-tools
    saas
    api
    email
  • Metriport
    Metriport (s2022)Active • 6 employees • San Francisco, CA, USA
    Metriport helps healthcare organizations access and manage comprehensive patient medical data. Through a single integration, Metriport ensures clinical accuracy and completeness of medical information to providers, delivering comprehensive consolidated patient clinical data at the point-of-care. By standardizing, de-duplicating, consolidating, and hydrating the data with medical code crosswalking, providers get a rich understanding of their patients' medical histories through Metriport. Metriport is the only open-source solution of its kind that offers all these integrations in a single platform, and standardizes complex data formats into industry standards such as FHIR and C-CDA. As a developer-first, HIPAA and SOC 2 Type II compliant interoperability solution, Metriport is powering the next wave of innovators in healthcare, creating an internet for healthcare data.
    developer-tools
    b2b
    digital-health
    healthcare
    api
  • Finch
    Finch (s2020)Active • 63 employees • San Francisco, CA, USA
    Finch is the API to access payroll and HR systems. We allow admins to connect their company in a compliant and secure manner to applications. Finch integrates across providers enabling developers to access a previously closed system and are at the source of truth for employee data and money flow. Our API powers use cases across lending, insurance, benefits, FP&A, and HR applications.
    fintech
    hr-tech
    api
  • Escape
    Escape (w2023)Active • 6 employees • Paris, France
    Find and fix business logic vulnerabilities in your applications in CI/CD before production — powered by Escape’s industry-leading API security intelligence.
    developer-tools
    security
    api
    graphql
  • Seam
    Seam (s2020)Active • 25 employees • San Francisco, CA, USA
    Seam lets developers connect and control 3rd-party connected devices like door locks, thermostats, and more.
    developer-tools
    iot
    api
  • FlowEQ
    FlowEQ (w2021)Active • 7 employees • Pleasanton, CA, USA
    FlowEQ is the trusted provider of workflow automation for teams that need to accelerate their work, especially complex processes and high-volume workflows that require human judgment. The FlowEQ Workflow Acceleration Platform includes interactive decision trees that are used by customer support, operations and product teams across all industries to improve accuracy and speed up important recurring work. Using FlowEQ customers get through high-stake recurring workflows 10x faster, saving their companies time and money every day. For additional information, visit www.floweq.com.
    b2b
    customer-success
    compliance
    api
    enterprise
  • ShortLoop
    ShortLoop (w2023)Active • 3 employees • Bengaluru, Karnataka, India
    We create up-to-date API collections, identify dependencies, breaking changes and API behavior without manual effort.
    developer-tools
    saas
    b2b
    api
  • Svix
    Svix (w2021)Active • 10 employees • New York, NY, USA
    Svix is the enterprise ready and open source webhooks service. Webhooks are a pain. Developers need to worry about deliverability, retries, monitoring and security. All of which are different for webhooks compared to the rest of the stack. We turn all of that into a simple API call. We are backed by Y Combinator, Andreessen Horowitz (a16z), Aleph, and founders and CTOs of companies such as Github, PagerDuty, Segment and Lookout.
    developer-tools
    open-source
    api
  • Dots 💸
    Dots 💸 (s2021)Active • 7 employees • San Francisco, CA, USA
    Dots is a developer-friendly API that lets businesses pay their contractors through just a few lines of code. Whether its gig workers like Uber drivers, sellers on marketplaces like Etsy, or simply your local handyman - Dots’ abstracts away the complexity of payouts completely. We manage the entire process: information collection (KYC), payments through any rail (ACH, Venmo, CashApp, Zelle, international, and many more to come), and even filing tax forms! Dots lets developers get payouts up and running over just a few hours, rather than the many months this would normally take.
    fintech
    payments
    api
    creator-economy
  • Wingback
    Wingback (w2022)Active • 12 employees • San Francisco, CA, USA
    Wingback provides tools and APIs for SaaS pricing and packaging. We are infrastructure that allows SaaS startups to deploy any set of features of their product using any pricing model. It enables non-technical teams to implement pricing and packaging changes and execute product-led growth campaigns without engineering involvement.
    fintech
    saas
    api
    enterprise
    infrastructure
  • Scaphold.io (w2017)Acquired • 2 employees • San Francisco, CA, USA
    Scaphold is the world's most powerful GraphQL as a service platform. The platform will provide a number of services including push notifications, analytics, file storage, custom code, multiple environments, and more to allow developers to build mobile, web, and IOT applications. Our innovative use of GraphQL is the big game changer here. We’re convinced that it’s the future of APIs and we want to make it readily accessible to everyone else.
    api
  • OneGraph
    OneGraph (s2018)Acquired • 2 employees • San Francisco, CA, USA
    Connect Twitter, GitHub, Stripe, Salesforce, and more through the power of GraphQL. Acquired by Netlify in Q4 2021.
    api
    graphql
  • Mailgun (w2011)Acquired • 51 employees • San Francisco, CA, USA
    Mailgun is a developer-focused email delivery platform that empowers companies to send, receive, and track transactional and marketing emails through an API. Founded in 2010, Mailgun became a Y-Combinator success story later acquired by Rackspace. In February 2017, Mailgun spun back out as a standalone business focused on building best-in-class email deliverability solutions. We are headquartered in San Antonio with remote teams in San Francisco and Austin. Customers like Slack, Lyft, Github, and Reddit rely on Mailgun to deliver email to their customers.
    api
    email
  • Rickshaw (w2014)Acquired • 11 employees • San Francisco, CA, USA
    Rickshaw is a local delivery platform that partners with courier companies and delivers several goods, including laundry, gifts, office snacks, and meal subscriptions. It uses algorithms and mobile apps to dispatch, route, and track customer locations. The service is available from Monday to Friday from 7.00 a.m. to 10.00 p.m. Rickshaw was launched by Divya Bhat and Gautam Jayaraman.
    delivery
    logistics
    api
  • Zencoder (w2010)Acquired • 11 employees • San Francisco, CA, USA
    Zencoder is a cloud-based video and audio encoding product suite from Brightcove (NASDAQ: BCOV), a leading global provider of cloud content services. The Zencoder service provides customers with high quality, reliable encoding of live and on-demand video and access to unlimited video encoding power without having to pay for, manage and scale expensive hardware and software.
    video
    api
  • Standard Treasury
    Standard Treasury (s2013)Acquired0 • San Francisco, CA, USA
    Standard Treasury helped banks harness the power of developers and developer ecosystems by building, hosting, maintaining, and supporting white-labeled and co-branded developer platforms for banks worldwide. Standard Treasury partner banks saw material top-line growth through the decreased cost of servicing their customers, decreased churn, and increased transaction volumes, while delivering tremendous value to their customers by allowing them to radically automate their treasury management and accounting processes.
    fintech
    payments
    api
  • SlidePay
    SlidePay (w2012)Acquired • 2 employees • Mountain View, CA, USA
    SlidePay, formerly Cube, is an API that makes it easy for any app to accept credit cards that are processed in person. Integration takes hours, not weeks, and works on any platform or device.
    fintech
    payments
    api