In this thesis we built a source code editor web application and documented all the steps. Main advantage of the application is text editing inside a web browser, with no need of any extra software installation. Automatic server side project saving allows users to change devices seemingly during work. With our application users have a tree structured representation of opened project, can open locally stored files or projects, edit multiple files in tabs, edit text, search for queries in an open file or within a collection of files and also save files back to hard drive. With syntax coloring support for eight common programming languages application makes it easier for users to read, write or edit code.