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Blockly Experiments

Google's Blockly is a web-based, visual programming editor. Users can drag blocks together to build programs. All code is free and open source.

This repository holds experimental code: projects that didn't work out, but might still be interesting references.

The Blockly library is at

Accessibility Demo

The code in this directory renders a version of the Blockly toolbox and workspace that is fully keyboard-navigable, and compatible with most screen readers. It is optimized for NVDA on Firefox.


We built this demo in 2016/2017 and tested it with students at a nearby school for the blind. The goal was to build workflows that combined the best parts of block-based programming (such as high-level abstractions about available functions and a lack of syntax errors) with keyboard-only navigation.

Lessons Learned

We learned that:

  • Students are not necessarily comfortable with a screenreader
  • Completely removing the visualization makes it difficult for a sighted and blind user to work together

Using the demo

Open the demo page. This demo uses the compressed version of the code.


To build the demo you will need the rest of Blockly. The accessible folder must be at the same level as Blockly's core folder. Run accessible to generate the compressed and uncompressed files.