Y Combinator Summer 2021 (S21) Companies

Membo operates a next-day grocery delivery service connecting European customers directly with local food producers rather than warehouse-based retailers. The platform prioritizes product freshness by coordinating direct delivery from multiple producers to consumers.

1 investor

A platform connecting people seeking career and business guidance with experienced mentors from top companies.

3 investors

Mentum provides AI-powered analysis tools that help procurement and supply chain teams process unstructured data into insights for sourcing decisions and cost reduction, serving industries including consumer goods, energy, automotive, and aerospace.

2 investors

Mergent provided infrastructure for background jobs and workflow execution, offering high-reliability job scheduling and queueing services for developers. The company has been acquired by Resend as of 2025.

1 investor

Meticulous automatically detects regressions in web applications by replaying user sessions at scale, helping front-end developers build more reliable software. The platform uses distributed replay systems and algorithms to identify code path coverage and differentiate meaningful test sessions.

2 investors

Micro Meat develops technological solutions to increase production capacity for cultivated meat manufacturing.

1 investor

Milkyway provides a platform for store-level inventory and stock management, enabling retailers to track out-of-stock (OOS) items and automate replenishment across their locations. The platform delivers real-time insights to improve in-store availability and sales performance.

1 investor

MindFi provides a workplace mental health platform offering employees access to care, practical resources, and organizational insights into workforce wellbeing. The platform serves global companies seeking to integrate mental health support across their operations.

3 investors

Mindmesh provides a centralized workspace where professionals can organize work items, notes, tasks, and calendar events in one location, enabling quick context switching and prioritization of current activities.

1 investor

Mindstate Design Labs is a clinical-stage drug development company that uses AI to map the biological basis of emotion and cognition, synthesizing psychedelic phenomenology and biochemical data to design pharmaceutical compounds that induce specific therapeutic emotional and cognitive states for mental health treatment.

4 investors

Mine offers AI-powered financial products including a credit-building debit card and an AI advisor for financial guidance, designed for individuals navigating wealth-building challenges.

3 investors

Miniloop is a SaaS platform that helps sales teams find, enrich, and manage leads through CSV imports, email verification, LinkedIn enrichment, and an AI discovery agent. It provides a unified workspace to track lead status from prospect to close.

1 investor

Mixr operates a platform that organizes virtual game tournaments for distributed and office-based teams, featuring integrated communication tools, game selection, and competitive leaderboards to encourage participation and team cohesion.

1 investor

MobileBoost builds AI-powered software that automates end-to-end testing for mobile applications. The platform helps QA teams increase test coverage while reducing manual testing workload.

2 investors

Momo Medical installs bed sensors in nursing homes that track resident activity and alert staff to potential falls and pressure injuries. The system provides nurses with real-time resident monitoring, helping facilities reduce fall incidents and bedsores while increasing shift productivity.

1 investor

Monet is a Colombian lending app that offers short-term credit lines of up to $500,000 COP with fast approval and no interest, charging fixed service fees instead. It uses open banking to analyze applicants' bank movements and serves individuals in Colombia, including those with negative credit reports, via app, website, or WhatsApp.

2 investors

Monto offers a modular benefits platform designed for companies to provide employee benefits with configurable options, integrated payroll deductions, and automated administration across organizations of any size.

2 investors

Moving Parts provides reusable UI components for iOS applications, designed to handle common interface elements with built-in support for styling, responsiveness, accessibility, and platform standards like dark mode and dynamic fonts.

1 investor

Nasdisc operates an online marketplace where buyers and sellers trade vinyl records, cassettes, and CDs. The platform addresses supply constraints and pricing volatility in the physical music media market.

1 investor

Nash provides AI-powered orchestration and dynamic routing for logistics networks, optimizing fleet, carrier, and fulfillment operations across verticals including grocery, retail, healthcare, and 3PL services. The platform automates dispatch decisions and coordinates autonomous vehicles, drones, and robots to reduce delivery costs and manual intervention.

2 investors

NeoDocs provides at-home health assessment tests with lab-quality accuracy and personalized health monitoring for consumers seeking preventive wellness. The company focuses on proactive health optimization rather than disease treatment.

2 investors

Nexus offers a combined checking and investment account that automatically invests the account balance to generate market returns while keeping funds accessible for withdrawal at any time, including after-hours.

1 investor

Nino Foods operates three quick-service restaurant brands (Nino Burgers, Francesco's Pizzeria, and KHA) across 20+ locations in Mumbai and surrounding areas. The company builds a fast food business focused on delivery and dine-in services for consumers seeking burgers, pizza, and fried chicken.

4 investors

Noloco is a no-code platform for building custom team intranets and applications that connect data from sources like Airtable, Google Sheets, and SQL. It serves organizations that want to centralize resources and automate workflows without requiring technical skills.

2 investors