Google Web Toolkit vs Transcrypt

Google Web Toolkit (GWT) is a free, open-source Java framework for building AJAX web applications. Its compiler converts Java applications into JavaScript and HTML for browser use, and the SDK includes the core libraries and compiler. Deferred binding generates browser-specific code at compile time, while the compiler can create separate application versions for different browsers and languages. Applications can communicate asynchronously with servers through GWT RPC or JSON. An Eclipse plugin provides IDE support and an option to install the SDK. The developer guide covers deployment to Google App Engine, JUnit unit testing and Emma code coverage; documentation also includes SafeHtml guidance for XSS prevention and GWT RPC XSRF protection. GWT is licensed under Apache 2.0 for non-commercial, commercial and enterprise applications. Version 2.13.1 is listed for Windows, Mac OS X and Linux. Development mode and the compiler periodically send a timestamp ID and product version to Google; Google says it does not log cookies or personal information. The webAppCreator utility has been deprecated since version 2.11.0.

Transcrypt compiles Python source code into JavaScript for browser applications. It converts a substantial subset of Python into JavaScript 6, with optional minification, and supports features including multiple inheritance, async/await, comprehensions, and modules. Developers can call JavaScript functions from Python and use browser DOM functions and JavaScript libraries. The distribution includes optional static type validation and consistency checks, plus multilevel source maps for tracing generated JavaScript back to the original Python. Transcrypt can also compile Python server code for Node.js and use Node libraries with require(). The project recommends installing it as a Python package with pip and documents testing on Windows, Linux, and OSX. Its focus is browser development and JavaScript libraries rather than desktop Python libraries. Because code is precompiled, Python exec and eval are unsupported, although JavaScript eval is supported. C and C++ libraries are not directly supported for browser use without special measures such as compiling them to asm.js. Transcrypt is free and open source under Apache 2.0.