skulpt.org

What It Is

Skulpt is an implementation of Python that runs entirely in the browser. It does not simply convert Python text into JavaScript that can be copied and run directly; instead, it compiles Python into JavaScript that depends on the Skulpt runtime, which is then executed by the browser. On the web, you typically include skulpt.min.js and skulpt-stdlib.js, then run code through APIs such as Sk.configure and Sk.importMainWithBody.

Core Capabilities

From a functionality perspective, Skulpt’s biggest value is “backend-free Python.” The documentation explicitly states that it requires no preprocessing, plugins, or server-side support: code runs completely in the browser. This makes it well suited to online education, interactive tutorials, embedded code examples, and lightweight IDEs. It provides a Python object runtime, compiler, built-in types, exceptions, scope handling, a module import mechanism, and more. It can also convert between Python objects and JavaScript objects via Sk.ffi.remapToJs / remapToPy.

Language and Ecosystem

Historically, the project was based on a Python 2.6-ish foundation. Updates indicate that the master branch is now built and run using the Python 3.7.3 grammar, though a large amount of lower-level implementation work remains, and Python 2 options will continue to be retained. The development toolchain has migrated to Node.js and Webpack. The examples integrate the CodeMirror editor and demonstrate turtle; modules can be placed under src/lib and packaged into skulpt-stdlib.js.

Open Source, Deployment, and Pricing

Skulpt is dual-licensed under the MIT License or PSFLv2. The main documentation does not mention a commercial edition or paid subscription. It naturally supports self-hosting: developers can build the dist files and host the JS assets on their own websites. Note, however, that the dual license mainly covers the Skulpt components included in the runtime; surrounding code used for building, testing, and related tasks may have different licenses.

Pros, Cons, and Who It’s For

Its advantages are simple deployment, fully client-side execution, suitability for educational use cases, and detailed documentation covering source code, compiled output, and module extension. The drawbacks are also clear: the project explicitly states that Skulpt is not complete, with some Python language features and standard library capabilities missing; Python 3 compatibility is still a work in progress; and extending the runtime requires understanding internal mechanisms such as CPython-style implementations, Sk.builtin, Sk.misceval, and Sk.abstr. It is better suited to education products, online practice platforms, and teams that need to run simple Python inside web pages. It is not ideal for scenarios requiring full CPython compatibility or the scientific computing ecosystem.

Access in China

The main documentation does not provide information about mainland China access, mirrors, payment methods, or related details, so access status is marked as unknown. If you need stronger compatibility or a richer ecosystem, alternatives such as Pyodide, Brython, Transcrypt, and PyScript may be worth evaluating.