y combinator batch

YC S21

391 companies listed, 391 classified into the radar taxonomy, compared against W21.

Cluster mix

16.6% 1.9pp vs W21
16.6% 1.7pp vs W21
13.3% 4.6pp vs W21
8.9% 1.8pp vs W21
8.4% 2.5pp vs W21
6.4% 4.4pp vs W21
3.3% 1.5pp vs W21
2.8% 1.7pp vs W21
2.3% 1.4pp vs W21
0.3%

Companies

The AI Native Billing Platform

Fintech

No-code email marketing platform to send forms & widgets within emails

B2B SaaS

No-code scoring engine identifying your most engaged upsell opps

B2B SaaS

Executable specifications in English for test automation

Developer tools

Build factory ready tech packs in minutes.

Commerce and marketplaces

Cloud and Container Security Platform

Security and compliance

Developer friendly drop in payouts infrastructure

Fintech

Geostar drives inbound for companies through search.

B2B SaaS

Autonomous medical care

Vertical AI agents

AI workflow engine for reliable systems

Agent infrastructure

Online Training for Healthcare Jobs

Healthcare and bio

Make all team work visible — people and AI agents

Agent infrastructure

We make software for bookkeepers.

Vertical AI agents

Project management on a live map

B2B SaaS

Automated data observability and quality for Data Lake

Data for AI

Carbon markets platform and solutions

Climate and energy

One source of truth for financial data.

B2B SaaS

Security Delivery Platform to orchestrate AI agents for Service…

Agent infrastructure

Open Source Infrastructure for the Financial Internet

Fintech

DNA App Store

Consumer

A modern-day mental healthcare company for global workforces.

Healthcare and bio

Patent-pending enzymes to break down common dietary triggers

Healthcare and bio

App to help people quit or cut back on alcohol use

Healthcare and bio

Uber for Healthcare in Latinamerica

Consumer

Close and activate your customers on WhatsApp

B2B SaaS

Segment for global payments

Fintech

Next-Gen Financial Analysis and Reporting with AI Agents

Vertical AI agents

Secoda is the AI layer for your Analytics

Data for AI

Track & Boost Your Brand’s Visibility in AI Search

B2B SaaS

Exa60

Web search rebuilt for LLMs

Data for AI

AI-powered equity research software

Fintech

Help ML teams label the right data

Data for AI

Modernizing hedge fund back office software and services.

B2B SaaS

The Best Data Infrastructure for Biotechs

Data for AI

1:1 ADHD coaching, 5-10X More affordable than alternatives

Healthcare and bio

Accelerate software development with WarpBuild's 10x faster CI infra.

Developer tools

Learning platform for job seekers with job applications automation

Vertical AI agents

AI Copilot for insights & strategy

Horizontal AI assistants

A national network of microschools bringing school choice to every…

Consumer

AI-driven mobile cybersecurity

Security and compliance

All 391 companies of S21

Updated hourly from the public YC directory. Companies sorted by AI-visibility score.