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YC S21 330 startups

YC S21 Startups

Every Y Combinator Summer 2021 company we currently index.

Last updated

2026-07-17

Hiring right now 2% 6 of 330

Open roles 130

Most-hired discipline Engineering

The Y Combinator S21 batch (Summer 2021) brought 330 tech startups into our index. This page lists every S21 company we currently track, with logos, taglines, and links straight to their own sites — no paywalled middleman. Notable S21 companies include Stepful, Tavus, Abatable, Abhi, and Abstra. Each profile surfaces team size, founding year, location, and open roles when their careers page is publicly scrapable. The S21 cohort skews toward Dev Tools, Healthcare, and AI / ML — common patterns we see in this batch. Recurring tags across these companies: SaaS, B2B, Fintech, Artificial Intelligence, AI. The directory's filter UI accepts any of them as a query. Geographically, the S21 batch we have leans toward San Francisco, London, and New York, with the rest spread across remote-first teams and other hubs. 2 of these are currently flagged as trending based on momentum signals; and the listing refreshes whenever the scrape runs, so changes propagate without a manual edit.

Online Training for Healthcare Jobs

eLearningHealthcare

Building the human layer of AI

Generative AIB2BVideo

Carbon markets platform and solutions

Carbon Capture and RemovalB2BClimate

Abhi is Pakistan's 1st financial wellness platform focusing on…

Automate finance operations with Python and AI

Artificial IntelligenceSaaSFinance

We're building fully automated labs for protein engineering

AI-powered Drug DiscoverySynthetic Biology

AI career platform for healthcare workers

MarketplaceSaaSRecruiting

Automation for dental clinics and insurance companies.

Artificial IntelligenceHealthcareHealth Insurance

Global platform for employee engagement with rewards&flexible benefits

SaaSHuman ResourcesB2B

Compound compliance: the central hub for meeting SEC obligations

FintechB2BRegtech

Affogato AI — Your Agent for instant TikToks, Reels, and ads.

Artificial IntelligenceGenerative AIAI

Feel close, even when apart. One meaningful conversation at a time.

Health & Wellness

Podium for local businesses in Latam

Build factory ready tech packs in minutes.

SaaSManufacturing

The medical record & infrastructure stack for digital health companies

SaaSB2BTelemedicine

One source of truth for financial data.

Aleph Solutions (Alephee)

We help automotive aftermarket brands to supply and sell parts online

MarketplaceB2BE-commerce

Building Job driven Virtual Tech University for India 🇮🇳

EducationIncome Share AgreementseLearning

We help high-growth startups go viral on autopilot

Offers insurance to customers in a convenient & transparent way

FintechInsurance

One API to get clean data from any website for your AI agents at scale

Artificial IntelligenceDeveloper ToolsAPI

Portable cryoablation to prevent cervical cancer

HardwareHealth TechMedical Devices

Marketplace to buy managed vacation homes through fractional ownership

MarketplaceTravelProptech

Blood Test for Early Detection of Ovarian Cancer

HealthcareDiagnosticsWomen's Health

AppX helps social media creators launch their own mobile apps.

EducationSaaSB2B

The AI-Native Turnkey Alternative Investment Platform (TAIP)

FintechFinanceInvesting

TURN STATIC DOCS INTO INSTANT ANSWERS

Developer ToolsB2B

Build frictionless signup flows in minutes

Developer ToolsSaaSB2B

The global financial platform for affluent consumers in the Americas.

FintechCrypto / Web3

Modern Checkout Platform for D2C brands in Southeast Asia

FintechE-commerce

The complete production quality platform. AI-powered E2E testing,…

Developer ToolsSaaSOpen Source

Build and share apps with friends

Artificial IntelligenceConsumerNo-code

Astek Diagnostics

One-hour antibiotic sensitivity testing

MicrofluidicsMedical Devices

Operating system for restaurants, focusing on Southeast Asia

Restaurant Tech

Apps to control technology addictions/ helping startups hire engineers

Mental Health Tech

Google-level engineering productivity suite

Developer ToolsSaaSB2B

Get matched with top 1% of talents in 24h

MarketplaceB2BRecruiting

Grow Your Wealth With Baraka

Smart micro financing for everyone

Machine LearningLending

Workflows for repetitive customer-facing tasks

SaaSB2BProductivity

One chat app to rule them all

Connect LinkedIn to your CRM to automate and track LinkedIn outreach.

SaaSB2BProductivity

Remote labor for restaurants

Artificial IntelligenceFood Service Robots & MachinesSaaS

Accounts receivable automation to help companies get paid faster

FintechSaaSPayments

We make bacteria and plants that clean up pollution.

BiotechSustainability

Speech and accent coaching app for non-native English speakers

EducationSpeech Recognition

The platform for buying, selling and managing residential construction

FintechMarketplaceProptech

No-code scoring engine identifying your most engaged upsell opps

AnalyticsNo-code

Chime for Canada, starting with cash advances

Software that helps employees pick their employee benefits.

Bringing back blimps

RoboticsDronesAdvertising

Buró de Ingresos

The Work Number for LatAm

Increasing restaurant profitability through our AI Operating System

Ghost KitchensB2BE-commerce

Bytebot is the open source container for AI desktop agents.

Generative AIRobotic Process AutomationSaaS

Private workspace for founders, investors, and advisors to collaborate

SaaSB2BCommunity

Your Workplace Engagement Hub

CommunityHR TechSocial Network

Semi-Autonomous Diagnostics for Emergent Care

Artificial IntelligenceMedical Devices

Decarbonizing the fashion industry

SaaSSustainable FashionClimate

Learning platform for job seekers with job applications automation

EducationFintechRecruiting

Global online sales platform

Catena Biosciences

Using protein coupling to build new therapies

BiotechTherapeutics

The dynamic single-cell analysis company

AI-powered Drug DiscoveryMachine Learning

Automated communication between hospitals and patients in Latam

Machine LearningConsumer Health ServicesB2B

Charge Robotics

Robots that build solar farms

RoboticsSolar PowerConstruction

B2B e-commerce and fintech platform for traditional proximity stores

FintechGroceryE-commerce

Quickbooks for SMBs in Latam

Cloud and Container Security Platform

Cloud Workload ProtectionDevSecOpsIdentity

Eliminate Cloud Waste. Attribute and Track Savings. Engage Engineers.

Developer ToolsFinOpsB2B

Demo Platform for API-First Companies

Empowering local businesses to sell online.

SaaSB2BE-commerce

Coinrule Automates Your Crypto and Stock Investments

FintechCrypto / Web3Trading

AI Copilot for insights & strategy

Generative AIMarket Research

Concord Materials

Automating procurement and finance for construction companies

FintechMachine LearningMarketplace

AI-enabled financial automation and intelligence for CPG Brands

Artificial IntelligenceFintechSaaS

We help Accountants automate work and serve their customers online

Security Delivery Platform to orchestrate AI agents for Service…

Battery Observability Platform for Electric Vehicles

ClimateElectric VehiclesAI

Next Gen ATS/CRM for Modern Recruitment Agencies

RecruitingSales EnablementTalent Acquisition

Bare-metal access to Brazil's Open Finance and Pix systems

Making it easy to sell personalized products online.

SaaSB2BE-commerce

Make all team work visible — people and AI agents

Artificial IntelligenceDeveloper ToolsSaaS

Datlo helps companies increase sales and expand through data

SaaSGeographic Information SystemB2B

Making it easy for employees to donate and volunteer with good causes.

SaaSB2BEnterprise

Workspaces on demand, paid by the minute.

MarketplaceSaaSProptech

We buy & track building materials for construction companies.

Artificial IntelligenceSaaSSupply Chain

Pioneering Breast Cancer Diagnostics for a Healthier Tomorrow

Medical Devices

Chat with your Data Warehouse

Artificial IntelligenceSaaSB2B

Developer friendly drop in payouts infrastructure

FintechPaymentsAPI

We make software for bookkeepers.

Measure and communicate engineering activity

Developer ToolsSaaSB2B

Payments and scheduling for services professionals in LATAM

FintechMarketplaceSaaS

Software that increases the value of oil & gas wells

AnalyticsEnergyBig Data

Making electric vehicle batteries affordable

Self-Service Data Prep and Blend Built for Data Teams.

SaaSOpen Source

We engineer proteins that control the operating system of biology.

Synthetic BiologyBiotech

AI-Powered ERP, MES, and Test Software for Complex Operations

Commercial Space LaunchSaaSSpace Exploration

Home medical equipment, prescribed online and delivered.

Sleep TechConsumer Health ServicesDigital Health

Business intelligence as code

Developer ToolsB2BAnalytics

Open-source monitoring for machine learning models

Developer ToolsMachine LearningB2B

Web search rebuilt for LLMs

Developer ToolsSearchAI

Uber for Healthcare in Latinamerica

MarketplaceConsumer Health Services

Female Invest is a social e-learning app for finance and investing

FintecheLearningInvesting

Liquid cooling solutions inspired by nuclear reactor cooling

HardwareClimateEnergy

We help students in Latin America graduate from College.

EducationeLearningCommunity

The Face Filter NFT Marketplace

Augmented RealityCrypto / Web3Virtual Reality

A neobank for Africa's 500 million youth

AI-Powered Business Development for Scientific Organizations

Automated Meal Planner & Nutrition Tracking

ConsumerFitnessHealth & Wellness

Supply chain finance for consumer brands

FintechB2BE-commerce

On-demand wage access service built for the African market

Virtual Co-working Community

ConsumerCommunityProductivity

Our mobile app reduces chronic pain for 100 million Americans.

fluke is a full-digital mobile operator in Brazil

B2BTelecommunications

Payments infrastructure for government benefits

FintechGovTechPayments

Open Source Infrastructure for the Financial Internet

Developer ToolsFintechPayments

Real-Time Collaborative Transport Management Platform

LogisticsSupply Chain

Community for 100M Indian Financial Market Traders & Investors

FintechCommunity

We are the marketplace for trading gaming skins & assets without scams

FintechMarketplaceGaming

Consumer Health ServicesGenomics

SaaS Platform to manage IT and buy business software

SaaSEnterprise Software

Geostar drives inbound for companies through search.

Your AI Data Analyst

SaaSB2BAnalytics

At-home spa, beauty & grooming services marketplace for LatAm

MarketplaceBeautyHealth & Wellness

Student communications platform for higher education

EducationSaaSB2B

The #1 Market Network for Government Contractors.

Harmonic Discovery

Multi-targeted therapeutics to treat complex diseases

AI-powered Drug DiscoveryBiotechHealthcare

We visually monitor space objects for governments and defense

Space ExplorationAerospaceDefense

Low-cost, high-scale EV charging platform for apartments (and more).

Close and activate your customers on WhatsApp

SaaSB2BProductivity

AI engineering capacity. Made simple. ⚡️

RecruitingHR Tech

Payments infrastructure for businesses scaling in APAC

FintechPayments

Simplified digital health insurance for Filipino SMBs

FintechPaymentsTelehealth

Native user-facing SaaS integrations for your customers

Developer ToolsSaaSB2B

Hudson Labs (formerly Bedrock AI)

AI-powered equity research software

Artificial IntelligenceFintechSaaS

Humane Genomics

A platform to make artificial viruses as cancer therapeutics.

Hard TechSynthetic Biology

Sell memberships to your Discord server

SaaSPaymentsCommunity

Web infra for AI agents

Developer ToolsB2BAI

Loan management software for private lenders

The Trading Terminal For Crypto Traders

FintechSaaSCrypto / Web3

AI-powered Application Control

Segment for global payments

Operating system for insurance agencies

Leading wealth management and investing platform in Vietnam

FintechInvesting

2 sided Marketplace for accelerating medical research

A self-help app for people to manage their ADHD.

Mental Health TechConsumer Health Services

Helping farmers maximize crop yield

SustainabilityAgriculture

Financial Platform for Migrant Families in America

FintechConsumerNeobank

A modern-day mental healthcare company for global workforces.

Digital HealthHealthcareHealth Insurance

Inversion Space

Turning space into a transportation layer for Earth

Hard TechHardwareTransportation

We make instant offers to buy homes in India

B2B payments, transforming Africa's cash economy

Jestor is a no-code platform for creating custom business tools.

B2BProductivityNo-code

Online University for Tech Professionals

AI-Enhanced LearningDeveloper ToolsEducation

KaiPod Learning

A national network of microschools bringing school choice to every…

EducationeLearningConsumer

Near Space Flying Machines

DronesAerospaceAI

Reducing energy costs & emissions in buildings.

Real EstateClimateRenewable Energy

Corporate Card solution for Indian businesses

Marketing agency for startups: 10x cheaper, better and faster

SaaSB2BAnalytics

Secure fraud prevention and authentication platform for developers

SaaSB2BSecurity

Kiwi Biosciences

Patent-pending enzymes to break down common dietary triggers

BiotechFood Tech

Easiest way for companies to process data requests from governments

GovTechComplianceLegalTech

Turbotax for México and LATAM

Artificial IntelligenceFintechSaaS

Automating wealth creation for 400M Indian millennials

Cohort-based online courses for professionals in Latin America

eLearningLatin America

The AI Native Billing Platform

FinOpsFintechSaaS

Lattice for Latam with personalized learning and development

EducationSaaSB2B

App for B2B companies to find customer stories and advocates

Autonomous medical care

Consumer Health ServicesTelehealthHealthcare

Fair, simple and accessible financial services

Fast and simple fintech financing

Multicurrency account & international payments for businesses

FintechPaymentsFinance

Help ML teams label the right data

Machine LearningData Labeling

Reading + Writing Club App for Kids

EducationSaaSMedia

Pelvic floor fitness made easy

HardwareConsumer Health ServicesWomen's Health

Organic and gourmet high-protein meals, designed for longevity.

GroceryMarketplaceDelivery

The global operating account you truly deserve.

Latin America's Deposits Marketplace for Banks

We make cancer care at home possible.

Hard TechConsumer Health ServicesMedical Devices

First personalized migraine clinic using genetics and telehealth.

Health TechTelehealthGenomics

AI-native CAD software for civil engineering

Artificial IntelligenceMachine LearningComputer Vision

Online delivery-only restaurant group in the Philippines

Ghost KitchensE-commerce

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

Reinventing respiration monitoring

Health TechMedical Devices

Malga is an API to accept payments with multiple payment providers

SaaSPaymentsB2B

AI-driven mobile cybersecurity

PrivacyCybersecurityDefense

Helps affluent Indians invest in automated options trading strategies

FintechTradingStocks

CRM for creatives (acquired by Helium Ventures)

IP operating software for brands and content companies

Artificial IntelligenceSaaSComputer Vision

Project management on a live map

SaaSGeographic Information SystemB2B

Developing milk-inspired therapeutics for infectious diseases

AI-powered Drug DiscoveryWomen's HealthTherapeutics

On-demand auto maintenance & repairs

Auto CommerceMarketplaceE-commerce

Medium Biosciences

AI-designed Affinity Reagents

Artificial IntelligenceMachine LearningBiotech

AI-Powered Assistant for Procurement and Strategic Sourcing

Artificial IntelligenceSaaSB2B

Incredibly reliable background task queues and cron jobs

Developer Tools

Automated e2e screenshot testing without writing or maintaining tests

Developer ToolsHard TechSaaS

Transforming Mental Health for Corporate Asia

Machine LearningMental Health TechB2B

Mindstate Design Labs

Clinical-stage AI neuroengineering platform

Machine LearningMental Health TechBiotech

AI workflow engine for reliable systems

AI native mobile testing.

Artificial IntelligenceDeveloper ToolsGenerative AI

We help nurses in nursing homes to be 30% more effective

Payroll-backed loans and cash advances in Latam

Salary on-demand platform for Latin America

A marketplace for vinyl, cassettes and cds

Art Trading PlatformsMarketplaceE-commerce

Nash is the digital logistics infrastructure for commerce

MarketplaceSaaSB2B

Instant lab tests on your smartphone

Artificial IntelligenceConsumer Health ServicesMedical Devices

Flexible Business Apps for Modern Teams

Developer ToolsSaaSNo-code

The UAE’s leading small business payments platform

FintechPayments

Online cohort based courses for architects, engineers and designers…

EducationeLearning

AirBnB for Small Warehouses

MarketplaceWarehouse Management TechB2B

Vertical takeoff and landing aircraft for major airlines

Hard TechAirplanesClimate

Preventive healthcare app for Latam.

Consumer Health ServicesPrimary Care

Onebrief makes military headquarters run seamlessly

SaaSGovTechDefense

The AI Agent for Autonomous Data Operations

Artificial IntelligenceSaaSB2B

Gusto for the UK

The fastest way to ship airtight AI

AIOpsDeveloper ToolsGenerative AI

Square for Europe

SaaSB2BE-commerce

Output Biosciences

Teaching Generative AI the Language of Biology

AI-powered Drug DiscoveryGenerative AIBiotech

Live video signing for real-time agreements

DocumentsSaaSB2B

Manage sales commissions and sales performance

P2P Cross border payments

Learning app for school students in Southeast Asia

EducationSaaSSubscriptions

Using the immune system to cure disease

AI-powered Drug DiscoveryBiotech

A mobile app. It allows employees to get paid their salary on-demand.

FintechSaaSHR Tech

Loans to Nigeria's SMEs in under 3 hours

Stripe for former Soviet Union countries

Growing seaweed to stabilize the climate.

Carbon Capture and RemovalClimate

One-stop-shop for restaurants to operate and grow their business.

Autonomous DeliverySaaSE-commerce

We help offline LatAm SMBs manage and accelerate their cash-flow

A white-label care enablement platform

Consumer Health ServicesDigital HealthHealthcare

Pipekit scales data & CI pipelines for enterprises

Developer ToolsOpen SourceData Engineering

Pirouette Pharma

We make injections as easy as pushing a button!

Health TechMedical DevicesBiotech

Create, launch, and optimize Facebook ads and ads on 10+ platforms

MarketingAdvertising

Building the next generation food ingredient champion.

ClimateClimateTech

Plaid for Brazil: we allow developers to access users' financial data

We are the frictionless way for companies to make payments.

FintechB2BTravel

A modern platform for content marketing & SEO.

SaaSMarketingSEO

AI for product formulation

Generative AIHard TechB2B

Promakhos Therapeutics

A therapeutics platform for curing inflammatory disorders

Computer vision that makes the industrial workplace, safer

Industrial Workplace SafetyMachine LearningB2B

Infrastructure management software for water & electricity companies

Enterprise Software

Make games and stories with AI

EntertainmentAI

App to help people quit or cut back on alcohol use

Mental Health TechConsumer Health ServicesConsumer

Tech-powered equipment rentals in Latam.

ConstructionB2B

Artificial IntelligenceDeveloper ToolsMarketing

Modernizing hedge fund back office software and services.

Activating an overlooked force in medicine - the patient.

BiometricsConsumer Health ServicesDigital Health

Revolve Surgical

Surgical robotics for every operating room

HardwareMedical RoboticsMedical Devices

We're building the One Medical for dental

Consumer Health ServicesDigital HealthTelemedicine

Interactive Product Demos

Advanced Contract MFG for fast moving hardware companies

RoboticsManufacturingIndustrial

AI-native on-call and incident response carefully crafted to help…

AIOpsDeveloper ToolsSaaS

Guiding cardiac therapeutics - all from your phone

AI-Enhanced LearningMedical DevicesTherapeutics

Safer Management

Student Attendance tracking for Public Schools

Artificial IntelligenceEducationMachine Learning

Mobile first solution for Payroll, employee & expense management

Gusto for India

Artificial IntelligenceSaaSB2B

Reliable blockchain indexing & querying for web3 engineering teams.

Developer ToolsSaaSCrypto / Web3

The Best Data Infrastructure for Biotechs

Generative AISaaSB2B

Secoda is the AI layer for your Analytics

Artificial IntelligenceSaaSB2B

Sensible Biotechnologies

Unlocking the next generation of mRNA medicines

Synthetic BiologyBiotechManufacturing

Conversational AI assistants using your knowledge

AI-Enhanced LearningArtificial IntelligenceAI Assistant

Sequin is building AI Voice Agents to automate collections calls for…

Generative AIB2BOperations

SFA Therapeutics

Regulating the immune system to block cancer & autoimmune diseases

AI-powered Drug DiscoveryAnti-AgingBiotech

Get data insights without writing SQL

AnalyticsEnterpriseAI

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

Mental Health TechCommunity

Amazon Level Logistics for eCommerce Companies in MENA.

Home Internet for urban Latin America

FintechCommunityTelecommunications

The new home for your internet 🏡

SaaSProductivityCollaboration

Noom for Southeast Asia

Consumer Health Services

Compound B2B SaaS for modern infrastructure to deploy and manage sites

Banking, corporate cards, stablecoin payments – available globally.

Browser automation for businesses.

Artificial IntelligenceMachine LearningE-commerce

The B2B Payments Platform

Artificial IntelligenceFintechMachine Learning

Single photo nutrition tracking.

Computer VisionFitnessAI

Visual AI shopping

Artificial IntelligenceConsumerChatbot

The most magical personal Voice-Led AI English Learning Buddy for Kids

AI-Enhanced LearningEducationGenerative AI

Latin Americas' first investing social network. Learn. Share. Invest.

AI native ATS + CRM for executive search firms

SaaSProductivity

Monetization platform for character creators

MarketplaceConsumerCommunity

Build Interactive Product Demo in 10 mins for SaaS companies

Flexible On-Demand Storage Space for Household, SMEs & Travellers.

Warehouse Management TechB2B

Automated phone ordering system for restaurants

Food Service Robots & MachinesSaaSE-commerce

$Strive Math$

Online Coding School for Kids 8-16

24/7 video platform & online community for students to study together

Autonomous team of AI agents that runs the entire hospital operations

Artificial IntelligenceSaaSHealth Tech

Subscription infrastructure & paywall experimentation for mobile apps

Developer ToolsPaymentsAI

We enable FMCG distributors in Africa buy inventory on credit

FintechMarketplaceB2B

Super AI Accountant for SMBs

Artificial IntelligenceFintechSaaS

Easy accounting for e-commerce

All-in-one digital ordering system for restaurants

SaaSE-commerceFood Tech

TAG is the First Digital Bank (Chime/Revolut/N26) for Pakistan

Discovering drugs that target the DNA regulome

BiotechGenomicsDrug discovery

Data pipeline for your security data lake.

B2BCybersecurityBig Data

Automate your cyber security risk assessments

SecurityCybersecurity

Automated data observability and quality for Data Lake

The World's Most Versatile Video Answering Engine

Artificial IntelligenceComputer VisionVideo

Executable specifications in English for test automation

Developer ToolsSaaS

The personal coach and companion for cyclists.

FitnessHealth & Wellness

Inclusive mental healthcare for companies

Super Hyperlocal Marketplace for SMEs in Indonesia

GroceryMarketplaceDelivery

Account Receivables Platform for Latin American Enterprises

FinOpsFintechSaaS

AI-native logistics OS for autonomous freight execution

LogisticsSupply ChainAI

TransAstra Corporation

Orbital logistics: Unleashing space industry, from Earth to asteroids

Space Exploration

One stop investment solution for retail investors in Latam

Banking for construction

FintechPaymentsConstruction

Transforming pharmacies in the UK into diagnostic centers

SaaSTelemedicinePrimary Care

Moving Things Around in Space, Imaging Space Objects When We're Not

Space ExplorationSatellites

Developers of ChitChat, an integrated messaging and payments wallet…

FinOpsFintechConsumer

AI Business Analysts to gather requirements and optimize processes

SaaSB2BAnalytics

CRISPR powered Diagnostics with results in minutes.

Nonprofit telehealth coaches for underserved Americans on Medicaid

Mental Health TechConsumer Health ServicesHealthcare IT

AI-powered Deepfake Detection

Artificial IntelligenceSaaSB2B

Plan and review AI generated code

Artificial IntelligenceMachine LearningOpen Source

Retaining employees in LatAm via education

EducationMarketplaceSaaS

AI for risk adjustment integrity

Health TechHealthcareHealth Insurance

Build Voice AI Agents

Artificial IntelligenceSaaSB2B

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

Developer ToolsGenerative AISaaS

Building Shein of Home: tech-driven, design-mfr Home Lifestyle Brand

Artificial IntelligenceMarketplaceE-commerce

Authorization and access control as a service.

Developer ToolsB2BOpen Source

Water risk mitigation for industrial sites

Machine LearningSaaSB2B

Manage your website from your favorite tools like Airtable and Notion

SaaSRemote WorkNo-code

Whaly is building a self-service analytics platform

Data Engineering

Track & Boost Your Brand’s Visibility in AI Search

Artificial IntelligenceGenerative AISaaS

Yemaachi Biotechnology

Diversifying precision cancer diagnostics and treatments

BiotechDiagnosticsTherapeutics

The everything app for LATAM

MarketplaceSaaSDelivery

Lovable for internal products

Artificial IntelligenceDeveloper ToolsSaaS

Immediate stroke detection at home

Sleep TechConsumer Health ServicesMedical Devices

Posture correction software

Consumer Health ServicesDigital Health

AI to understand and automates the physical world

AIOpsArtificial Intelligence

Help start- and scale-ups excel at People, Culture and Performance.

Mental Health TechSaaSB2B

We help businesses convert leads into sales in minutes using text

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Frequently asked questions

What is the YC S21 batch?

S21 is the Y Combinator batch code for the Summer 2021 cohort. Companies joining a YC batch go through a 3-month program in California and demo their product at the end. techstartupslist.com indexes 330 tech startups from this batch.

How many companies are in YC S21?

Our index currently tracks 330 active tech startups from the YC S21 batch. New companies appear here automatically when our daily scraper finds them; companies that shut down are flagged inactive and hidden from listings.

Which companies graduated from YC S21?

Among the S21 companies indexed here: Stepful, Tavus, and Abatable, and 327 more on this page. Click any profile for category, team size, founding year, and open roles.

Where can I find open jobs at YC S21 startups?

Open roles from indexed S21 companies appear on our /jobs page, aggregated alongside roles from other indexed startups. Each role links directly to the company's official application page.

How often is the YC S21 page updated?

Automated scrapers refresh this page daily. The last index update was 2026-07-17. Inactive companies fall out of the count automatically — we don't keep dead listings live.