Y Combinator funded AppJet is an online programming tool for building simple web apps. Founded by former MIT students, AppJet intends to simplify the process of writing web applications. The applications are programmed on a web based text editor in the simple but powerful JavaScript programming language. JavaScript is used on both the server and client side. They've included several bundles of code libraries for databases and more importantly interfacing with the Facebook API. In order to efficiently host users' applications, AppJet has developed their own application virtualization system. The system allocates processor time to active applications and cuts off greedy ones after running an alloted number of compiled lines of code to prevent abuse. AppJet as a dev platform seems no longer to be active. There are some legacy downloads available, however.
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AppJet was a developer-platform and collaboration startup founded by David Greenspan, Aaron Iba, and J.D. Zamfirescu in 2007 and accepted into Y Combinator's Summer 2007 batch. It began as browser-based hosting for server-side JavaScript, tried a PHP pivot, then turned internal real-time synchronization technology into EtherPad.[1][2]
Google acquired AppJet on December 4, 2009 and moved the team into Google Wave. The price was not disclosed. Contemporary estimates placed it in the low eight figures, but those reports are not confirmed terms.
The hosted EtherPad service eventually closed, but user backlash changed the transition. AppJet restored pad creation, released EtherPad and its framework under Apache 2.0, and enabled community successors. The current Etherpad project preserves the real-time editing model and remains actively self-hosted.

AppJet's archived company page names Greenspan, Iba, and Zamfirescu as a three-person executive team. All were MIT alumni; Iba and Zamfirescu had worked at Google. Greenspan specialized in virtual machines and JavaScript, Iba led front-end work and business, and Zamfirescu wrote the web server and persistent-storage system.
The founders wanted beginners and experienced developers to build simple web applications without configuring several languages and infrastructure layers. Iba described the frustration directly: “We were sick of all the hassle of setting up servers, configuring apache, installing MySQL and php and mod_whatever.”[3]
The public beta launched in December 2007. Developers wrote JavaScript in a browser editor, saved it, and published immediately to a hosted URL. AppJet supplied database and Facebook libraries, free hosting, and 10 MB of storage.[4] Source code was inspectable by other users, combining deployment with a learning environment.
The first platform tried to build both a web framework and a hosting service. YC later described this as attempting Rails and Heroku simultaneously, too much infrastructure and product for the startup's financing.[5] A second incarnation moved toward PHP, but YC said the founders disliked the work and abandoned it.
The third incarnation returned to JavaScript and exposed the team's difficult real-time synchronization libraries. EtherPad began as an internal tool and technology showcase. It became the company because users wanted collaborative editing more than a general development platform.
The packet contains only one direct founder quote. No second founder quotation about the pivot or acquisition surfaced, so one should not be reconstructed from secondary paraphrase.

The original AppJet product was a browser-based editor, runtime, and hosting platform where JavaScript ran on both client and server. Its stack used the Java virtual machine, Mozilla's Rhino engine, and Scala libraries. Developers received an online editor, custom domains, tutorials, examples, storage, hosting, and a support forum.
Read the complete post-mortem, the rebuild playbook, and the exact reasons Appjet is still worth studying now.