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Moldo

Moldo is a visual educational programming language. Instead of writing text code, learners drag and connect blocks on a canvas to build programs. When they press Run, Moldo compiles the visual graph into Python and executes it - showing the output in real time.

  • Block-based

Programs are built by connecting visual blocks. No syntax errors, no blank-page anxiety.

  • Extensible via molds

Anyone can publish new block types as a .zip.mold package - no changes to the core needed.

  • Built for learning

Real Python under the hood. Learners build intuition about flow, variables, loops, and functions visually first.

  • REST API

A FastAPI backend exposes everything over HTTP. Build your own editor or integration on top.

How it works

  [mflow-editor]          [moldo backend]
  ─────────────           ───────────────
  Learner drags     →     Receives JSON
  and connects            program tree
  blocks on canvas
                    →     Compiles to
                          Python source
                    →     Executes and
                          streams output
  Shows output      ←
  and highlights
  active nodes

The mflow-editor is an Electron desktop app (plain HTML/JS, no framework). It talks to the moldo FastAPI backend over HTTP on localhost:8000.

Quick start

pip install moldo
moldo serve
# → running on http://127.0.0.1:8000

git clone https://github.com/GracePeterMutiibwa/moldo
cd moldo
python3 -m venv .venv && source .venv/bin/activate
pip install -e .
moldo serve

Then open the mflow-editor desktop app, drag some blocks, and press Run.

What are molds?

A mold is a self-contained package that adds new block types to the editor. The 7 built-in capabilities (variables, I/O, control flow, math, text, collections, functions) are all molds - there is no special-casing.

Community developers can build and distribute molds for anything: web scraping, image processing, data analysis, hardware control, or game logic.

→ Learn how to create a mold