What they do:
Classify Anything
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HQ: CA, United States
Top API Startups
This list has 147 startups and was last updated on Oct 15, 2026. 41 of them are hiring right now. Biggest hubs: San Francisco (73), New York (14), and Los Angeles (6). Largest teams: Checkr, Bird, and Verto.
147 startupsPage 3 of 5
What they do:
Build an API to interact with any website.
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HQ: San Francisco, CA, United States
What they do:
API for shared embeddable web browsers
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What they do:
Realtime Data Connectors
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HQ: Mexico City, Mexico
What they do:
High precision AI weather
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HQ: Ann Arbor, MI, United States
What they do:
Stripe for telephony
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HQ: Lehi, UT, United States
What they do:
AI Search for the Next Generation
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HQ: San Francisco, CA, United States
What they do:
Open-source API & UI test automation
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HQ: Wilmington, DE, United States
What they do:
Deploy Machine Learning Models with One Command
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HQ: San Francisco, CA, United States
What they do:
Programmable API gateway that makes APIs cacheable
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What they do:
The open source Postman alternative.
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HQ: San Francisco, CA, United States
What they do:
Cursor for AI Agents
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What they do:
Build chat-with-data agents for customer-facing applications
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HQ: Limerick, Ireland
What they do:
AI media creation platform for creators and developers
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HQ: San Francisco, CA, United States
What they do:
The best DOCX MCP for agents to edit microsoft word documents
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HQ: San Francisco, CA, United States
What they do:
AI documentation engineer – test & autoimprove stale product docs
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HQ: San Francisco, CA, United States
What they do:
We turn complex API integrations into drop‑in full‑stack libraries
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HQ: Amsterdam, Netherlands
What they do:
Self-tuning search for products and files
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HQ: San Francisco, CA, United States
What they do:
API sandboxes, built for AI agents
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HQ: San Francisco, CA, United States
What they do:
Bring AI to life with the world's best interactive avatars
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HQ: Los Angeles, CA, United States
What they do:
The people data company for the agent era
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HQ: San Francisco, CA, United States
What they do:
Turn any website into an MCP for your agents, in minutes
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HQ: San Francisco, CA, United States
What they do:
Durable state for AI agents
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HQ: New York, NY, United States
What they do:
Universal, Pure-GPU HTML Renderer
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HQ: San Francisco, CA, United States
What they do:
AI Agent for Billpay platforms to pay invoices with virtual cards
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HQ: San Francisco, CA, United States
What they do:
Specialized agents for real work
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HQ: Los Angeles, CA, United States
What they do:
Make your LLMs 3x faster.
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HQ: San Francisco, CA, United States
What they do:
Turning messy inboxes into ERP-Ready Data
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HQ: San Francisco, CA, United States
What they do:
Managed Agents API
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HQ: San Francisco, CA, United States
What they do:
Accelerating world models.
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HQ: San Francisco, CA, United States
YC X25Early stage
DrChrono
Acquired
What they do:
The essential platform for modern medical practices and patients.
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HQ: San Francisco, CA, United States
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HQ: New York, NY, United States
YC W23Early stage
Ribbon Health
Acquired
What they do:
Health enterprise API for data on doctors, insurance, costs, & quality
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HQ: New York, NY, United States
Mailgun
Acquired
What they do:
Email API service.
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HQ: San Francisco, CA, United States
Dyte
Acquired
What they do:
Real-time audio & video SDKs, ready to launch 🚀
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PlayAI
Acquired
What they do:
Our mission is to make Voice AI accessible and useful to all.
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HQ: San Francisco, CA, United States