Y Combinator Winter 2009 (W09) Companies

Airbnb is an online marketplace that enables people to book and list accommodations for short-term rentals, experiences, and services around the world.

52 investors

Cloudkick provides monitoring and alerting tools for cloud servers running on services like Rackspace Cloud and Amazon EC2, along with dashboards and categorization features to track server health and performance.

1 investor

A photo-sharing service that allows users to upload and distribute uncompressed images to their social contacts.

1 investor

Echodio provided cloud synchronization and backup for music libraries, allowing users to access and stream their collections across multiple devices and media players.

1 investor

Goldbelly is an online marketplace that ships iconic foods, meals, desserts, regional specialties, and gourmet food gifts from restaurants and local food makers to customers across the United States.

1 investor

Heyzap operates a mobile advertising network that connects app developers with users through SDK integration on Android and iOS, offering monetization, app discovery, mediation, and cross-promotion services.

3 investors

Nambii offers a mobile dating platform accessible via iPhone apps that enables users to exchange flirtatious messages with nearby people.

1 investor

Picurio provides a web platform for organizing and sharing photographs online.

1 investor

A music discovery platform where listeners vote on indie tracks using a daily allotment of hearts, earn reputation and badges for engagement, and organize music into tag-based playlists.

1 investor

A mobile email application that stores email locally on iPhones and provides full-text search across messages.

1 investor

Skysheet builds a spreadsheet application that runs in the web browser.

1 investor

1 investor

Volantio develops Vector, an agentic AI platform that helps airlines optimize passenger journeys and revenue through real-time demand management, overbooking optimization, and operational disruption resolution. The platform integrates with existing airline systems to identify and act on revenue opportunities while maintaining safety guardrails.

3 investors

Voxli provides browser-based voice chat for groups of up to 200 people, accessible via shareable persistent URLs without requiring server setup. The service targets gamers and team collaboration users on Windows and Mac, and includes push-to-talk functionality.

1 investor

Wattvision provides software and hardware sensors that allow buildings to view their electricity usage in real time through a web interface, partnering with hardware manufacturers to integrate its monitoring technology.

1 investor