Y Combinator Summer 2021 (S21) Companies

AOA Dx develops a blood-based liquid biopsy platform using mass spectrometry and machine learning to detect ovarian cancer at early stages through tumor-associated biomarkers in serum. The company serves oncologists and patients in women's health diagnostics.

22 investors

Apollo offers a debit card that grants users fractional stock rewards on purchases, with additional opportunities to win full shares of selected stocks.

1 investor

AppX provides a SaaS platform that enables content creators and educators to build branded websites and mobile applications without requiring technical expertise. The platform offers monetization tools including courses, webinars, memberships, merchandise, and live streaming functionality, primarily serving educators, online instructors, and digital content creators.

2 investors

Aqua provides a platform that automates the management of alternative investment assets for investors.

1 investor

Archbee is a documentation and knowledge portal platform that enables teams to create, organize, and share technical documentation with customers and internal users. It provides API documentation, in-app guides, FAQs, and knowledge bases with features like AI-powered search, SEO optimization, and integration capabilities.

2 investors

Arengu provides a platform for building signup flows with minimal engineering effort, targeting companies that lack dedicated teams to optimize user registration experiences and typically achieve conversion rate improvements in the 20-30% range.

2 investors

ARQ Finance (formerly DolarApp) is a digital financial platform that enables currency exchange to digital dollars and euros, international payments, and investment access to global markets. It serves individuals seeking low-cost cross-border transactions and international investment opportunities.

3 investors

Arrow provides a checkout platform tailored for direct-to-consumer brands and merchants in Southeast Asia, enabling customers to purchase across multiple channels without repeated account setup or authentication steps. The platform streamlines payments through local methods and mobile-first experiences designed for the region's shopping preferences.

2 investors

Artillery is a performance testing toolkit that provides load testing, Playwright-based end-to-end testing, and production monitoring capabilities for web applications and APIs. It serves development and DevOps teams that need to ensure application performance and reliability at scale.

1 investor

A platform for creating and sharing mini-apps and games built by community developers, featuring AI-powered features like video generation and image scoring alongside casual gaming experiences.

1 investor

Astek Diagnostics develops a diagnostic platform for rapid and accurate detection of urinary tract infections and related conditions in clinical specimens. The company serves physicians and patients needing point-of-care diagnostic solutions for infectious diseases.

2 investors

Atlas is an all-in-one operating system for restaurants that unifies online ordering, point-of-sale, kitchen management, and delivery platform integration. It serves food and beverage operators across Southeast Asia with storefront, table ordering, kiosk, and omnichannel commerce capabilities.

1 investor

BlockerX is a content-filtering software that blocks access to pornographic websites and custom sites across browsers, mobile apps, and devices. It serves individuals seeking to reduce porn consumption, parents protecting children, and professionals aiming for productivity through accountability features and personalized recovery plans.

1 investor

Aviator provides a GitHub app that automates code review assignment and management for engineering teams. The platform tracks review metrics, routes pull requests to appropriate reviewers based on expertise and load, and enforces service-level objectives for review response times.

1 investor

Awesomic is a talent marketplace that connects businesses with freelance contractors and creative talent to complete projects and tasks. The platform serves companies looking to hire independent workers for work assignments.

3 investors

Baraka is an investment platform that provides tools and market insights for retail investors to make long-term investment decisions. The platform targets young populations in the Middle East who lack access to investment apps and financial markets.

5 investors

Baubap is a regulated Mexican financial services company that provides microloans up to MXN 9,000 through a mobile app, using mobile-based evaluation rather than traditional credit history or income verification. The platform serves individual borrowers seeking short-term credit with transparent terms and rewards for on-time payment.

6 investors

Beau automates data extraction and organization from client files, delivering structured data in formats like filled PDFs, CRM integrations, and spreadsheets. The service eliminates manual data entry for businesses that collect client information through forms.

1 investor

Beeper is a unified messaging app that consolidates popular messaging services into a single cross-platform interface. It supports Android, iPhone, iPad, ChromeOS, macOS, Windows, and Linux, with optional paid features for power users managing multiple accounts.

1 investor

Birdie is an AI assistant that helps sales and prospecting teams research leads, generate personalized outreach copy, and manage follow-ups integrated with existing sales tools.

3 investors

Bite Ninja provides remote order-taking technology that enables restaurant staff to process drive-thru and takeout orders from remote locations. The platform helps restaurants address staffing shortages and increase operational flexibility.

2 investors

A subscription video platform that helps Black viewers discover and watch content created by and featuring Black creators and performers.

2 investors

Blixo is a billing and accounts receivable automation platform that combines subscription management, invoicing, collections, and cash application software. It helps businesses get paid faster by automating the entire invoice-to-payment process.

1 investor

BluumBio identifies and deploys naturally occurring enzymes from fungi, trees, and bacteria to remove industrial pollutants from soil, air, and water. The company serves environmental remediation projects requiring rapid decontamination of petroleum, pesticides, plastics, and other synthetic chemicals.

3 investors