YC Summer 2009 (S09) companies

AdThrow builds B2B advertising technology products. No further details about its specific product, target customer, or the work it replaces are available from public sources.

Bump built mobile apps that let users exchange contact information and photos by physically tapping two phones together, replacing manual entry and file-transfer workarounds. A second app, Flock, automatically matched photos to the friends present when they were taken and organized them into private shared albums. Both apps were shut down after Google acquired the company in 2013; the unreleased Photoroll app became the foundation for Google Photos.

CarWoo builds a marketplace that connects car buyers with competing dealerships, letting shoppers solicit and compare offers from multiple dealers in one place. It replaces the traditional dealership visit and one-at-a-time negotiation process, reducing the stress and information asymmetry that typically disadvantages buyers. Dealers participate to reach motivated, purchase-ready customers.

DailyBooth gives consumers a photo-driven social feed where they post pictures paired with short status updates and follow friends doing the same. It replaces text-heavy status updates with a visual, snapshot-first format for staying current with people's daily lives.

Directed Edge builds a product recommendation engine for e-commerce sites, replacing the need to build in-house recommendation logic. It analyzes existing purchase and click histories to surface related products, personalized picks, cart suggestions, and bundle offers in real time. A REST API with multi-language bindings handles integration, and a native Shopify app extends the same capabilities directly to merchants on that platform.

Fanchatter collects and surfaces organic social commentary that fans already produce about a brand, team, or topic, then gives publishers and marketers tools to curate and redistribute that content. Customers range from large media companies to individual bloggers. The product replaces paid advertising creative by turning existing fan enthusiasm into promotional material.

Flightcaster predicts domestic flight delays hours before airlines or other apps surface them to travelers. It runs a proprietary algorithm against a decade of historical flight data combined with real-time conditions to produce delay probabilities. The product replaces the wait for official airline notifications, giving passengers early warning to act on.

GraffitiGeo builds a location-based restaurant discovery and rating app that lets consumers quickly vote or leave brief comments on restaurants from an iPhone app or website. It replaces long-form review platforms with a stripped-down thumbs-up/thumbs-down system, a regional heatmap of popular spots, and a points-driven game layer where groups of friends pool credits to claim virtual territory tied to real city blocks.

HighlightCam builds a mobile app that continuously buffers the last 15 seconds of video so users can capture a highlight the moment it happens, rather than missing it by reacting too late. The app targets consumer users filming live action, particularly in youth sports contexts in New Zealand, replacing the need to anticipate and manually start recording in advance. Saved clips can be shared directly to social media or posted to SportyNews.co.nz.

Instantq builds an online platform that lets restaurants push just-in-time promotions directly to their customers. The tool replaces manual, time-delayed marketing by letting operators send deals at the moment they need to fill seats or move inventory.

Jobspice builds an online resume builder for job seekers. Users create, style, and manage multiple resume versions, then export them as PDFs or web pages, replacing manual formatting in word processors and the hassle of maintaining separate files for different employers.

Lingt builds a web-based tool for language teachers to create, assign, and assess spoken language exercises. Teachers use a drag-and-drop interface to build assignments with voice, video, and images, then collect and review student recordings and give individual feedback. The product replaces in-person language lab sessions and scheduled practice interviews.

Listia runs a mobile auction marketplace where people trade used goods without exchanging money. Sellers list unwanted items and buyers bid using points, which members earn by listing items, completing sales, and staying active on the platform. The model replaces traditional resale fees and cash transactions with a credit-based barter loop for consumer goods across dozens of categories.

Lockitron builds a hardware device that attaches to standard deadbolt locks and lets users lock or unlock their doors remotely via a mobile device or remote control. It targets homeowners and replaces the need for physical keys or in-person access management. The hardware sits on the inside of an existing door, requiring no locksmith or lock replacement.

Mixpanel builds event-based product analytics for software teams, giving engineers, product managers, and business users direct access to data on how customers interact with their products. It replaces ad-hoc data pulls and reliance on dedicated analysts by letting any team member query, visualize, and act on behavioral data without writing SQL.

NudgePad built a browser-based IDE that lets developers and designers spin up a fully hosted custom app in seconds, skipping server setup, DNS, SSL, version control, and API wiring. It targets anyone who needs to prototype quickly, from engineers to non-technical designers and copywriters who can edit app content through templates without writing code. NudgePad joined Microsoft in 2014.

Olark builds live chat and AI agent software for businesses that sell and support customers on their websites. The AI agent answers visitor questions, qualifies leads, and routes conversations to humans, replacing manual chat handling and static chatbot flows. It trains on a company's live site content and uses visitor behavior, such as pages viewed and return visits, to engage at the right moment in the buying process.

Plurchase builds a social layer on top of existing online retail sites, letting shoppers browse stores like Zappos alongside friends in real time. A persistent sidebar lets users chat and see what their contacts are viewing across participating shopping destinations. It replaces the solitary online shopping experience with a shared, coordinated one.

RentHop runs an apartment rental marketplace connecting renters with brokers and property managers in New York. Its ranking algorithm scores listings by freshness, accuracy, and landlord responsiveness, replacing the manual work of sifting through stale or incomplete postings. Renters search and schedule viewings through list or map views; brokers and property managers promote listings and capture qualified leads through the platform and a companion mobile app.

RethinkDB builds an open-source, scalable database for developers who need to push live data to applications without polling. Instead of requiring apps to repeatedly query for updates, RethinkDB streams continuously updated query results directly to the application the moment data changes. Developers use it to build realtime apps, multiplayer games, IoT pipelines, and streaming analytics dashboards with significantly less backend engineering than traditional database setups require.

RoboHR builds human resources software for businesses. Beyond the name, no details about the product, target customer, or the work it replaces are available from public sources at this time.

Stackq builds B2B software products. No program description or website content is available to specify the customer, the job performed, or the work the product replaces.

Stripe builds payment and financial infrastructure for businesses operating online, from early-stage startups to large enterprises. Its platform handles payment acceptance, business banking, billing, card issuance, and cross-border money movement, replacing the need for companies to assemble those capabilities from separate providers. Developers and finance teams use it to manage the full transaction stack, across 135+ currencies and payment methods, without building the underlying infrastructure themselves.

Tuxebo builds a peer-to-peer rental marketplace where people list and borrow physical items from one another. It targets owners who have underused goods and renters who need something temporarily, replacing outright purchases or trips to traditional rental stores.

Wakemate builds a wristband-and-app system that wakes consumers at the lightest point in their sleep cycle rather than at a fixed alarm time. A wrist-worn actigraph tracks motion throughout the night, and the paired iPhone app triggers the alarm at the end of a REM cycle within a set window. The Analytics Platform then delivers a full breakdown of the user's sleep patterns and circadian rhythms, replacing guesswork with motion-derived data.

WePay builds a multi-party payments API for platform businesses, serving SMB SaaS providers, point-of-sale platforms, and online marketplaces. It replaces the need for each platform to negotiate and integrate payment processing independently, letting the platform handle payouts to multiple parties through a single interface. JPMorgan Chase acquired WePay in 2018.