Skip to content
Blockly that's more Python than JavaScript, powered with Skulpt
JavaScript Python HTML Other
Branch: master
Clone or download
Type Name Latest commit message Commit time
Failed to load latest commit information.
advertising Accessibility improvements beginning Jul 2, 2019
docs Adding docs, removing bad old code Mar 26, 2017
fonts Upgrade bootstrap, hide/show settings menu May 8, 2017
images Fix +/- for tuples, separate blockly blocks Jun 24, 2017
libs Accessibility upgrades Jul 3, 2019
src Accessibility upgrades Jul 3, 2019
tests Fixes for Upload mode Sep 13, 2017
.gitignore Hide skulpt Sep 9, 2018
LICENSE Initial commit May 13, 2014 fixed typo should be blockly, not blockpy. Added lines for note of py… Apr 4, 2019
blockpy_new.html Accessibility upgrades Jul 3, 2019 More Tifa bindings Jan 28, 2018
canvas_frame.html Major revisions for v3 May 11, 2016
engine_test.html Tifa improvements, properties=>variables, engine only mode Jan 10, 2018 Upload mode, corgis integration, uploading block images Aug 9, 2016
iframe_test.html Glyphicon fonts, alternative layout Jun 25, 2015
index.html Force update option, imrpoved tracebacks on student errors Jan 14, 2019 PAISC supports list comprehensions Sep 26, 2017
makefile Allow sandbox to import more fake stuff in engine Jan 14, 2019 Pedal, engine updates, skulpt improveemnts Aug 6, 2018
replay.html Created some utility functions Dec 6, 2017
server.js Tifa fixes, fix for large strings, improved unit tests Mar 30, 2018
todo.txt New instructor API features Mar 4, 2017
treeCompTest.html include TIFA bindings in the treeCompTest.html Feb 4, 2018



BlockPy is a web-based Python environment that lets you work with blocks, text, or both. Designed for Data Science and equipped with powerful tools like the State Explorer and Guided Feedback, the goal of BlockPy is to let you solve authentic, real-world problems.

The goal of BlockPy is to give you a gentle introduction to Python but eventually mature you into a more serious programming environment (such as Spyder or PyCharm). Long-term, we may support some game/animation design stuff that Scratch/Snap does, but that's not the real goal.

The BlockPy project is aimed at solving some hard technical problems: having a block-based environment for a dynamic language can be tricky - are a given pair of square brackets representing list indexing or dictionary indexing? Our goal is to use advanced program analysis techniques to provide excellent support to learners.


The core architecture of BlockPy is a synthesis of:

  • Blockly: a visual library for manipulating a block canvas that can generate equivalent textual code in a variety of languages
  • Skulpt: an in-browser Python-to-JavaScript compiler/intepreter, that aims to emulate the full language with precision if not speed.

By combining these two technologies, we end up with a powerful system for writing Python code quickly. Everything is meant to run locally in the client, so there's no complexity of sandboxing students' code on the server.

The major innovations are:

  • PythonToBlocks: by parsing the AST generated by Skulpt, we can build equivalent Blockly code, effectively allowing round-trips between text and blocks.
  • CORGIS Datsets: new blocks access real-world datasets (although currently these are only cached versions, for performance reasons).
  • Interactive Guided Problems: Problem text is given to students, along with teacher provided code that can do analysis on the students' code and make suggestions (e.g., observing that they haven't printed anything yet).
  • Data Explorer: The data explorer allows users to walk through their code.


First, setup a root directory for this project. This directory should look something like this:

        ...contents of blockly
        ...contents of blockpy
        ...contents of closure library
        ...contents of skulpt

The respective commands to create these folders should be something along the lines of (note that some of these clones can take a while):

> git clone
> git clone
> wget -O
> unzip
> git clone

You'll need to build Skulpt and Blockly. Both of these depend on the Closure Compiler, so you'll need to put that in the empty closure-library folder.

CD into your root directory

> cd root/

Next, you'll need to build Blockly. The en.js file doesn't quite build correctly so you want to copy it out and paste it back in. It should be something along the lines of:

> cp blockly/msg/js/en.js en.js
> cd blockly
> python
> cd ..
> mv -force en.js blockly/msg/js/en.js

Note that blockly builds in python2

And then you'll build Skulpt:

> cd skulpt
> python dist
> cd ..

Note: You may have to create a "dist" folder in the skulpt directory Note: skulpt builds in python3

If you are on windows, you may encounter the message "No gzip executable", you can safely ignore this.

And now you should be able to try out the example file!

> start blockpy_new.html

The server has its own requirements.txt and uses a python runserver

If you make edits to either Blockly or Skulpt, you'll need to rerun their build commands. Simiarly, if you edit src/interface.html than you'll need to rebuild it:

> python

Otherwise, you should be able to edit the src/*.js files freely. To get a sense of the dependencies, check out the blockpy_new.html file and then the src/main.js file. These should be good starting points.

You can’t perform that action at this time.