Ardublockly
Ardublockly is a visual, drag-and-drop programming editor for Arduino boards, built on Google's Blockly, that generates Arduino C++ code and can upload it directly to a connected board.
Ardublockly is a visual programming editor for Arduino, forked from Google's Blockly and extended to generate Arduino code. A local Python server, ArdublocklyServer, compiles and loads the generated code onto a board through the Arduino IDE, and the whole thing ships as a self-contained desktop application for Windows, macOS and Linux.
Features include drag-and-drop code generation, direct uploading to a connected Arduino board, warnings on generated code blocks, and compatibility with a wide range of official Arduino boards. A "core version" runs just the Python server and loads the editor in a local browser instead of the packaged desktop app. The repository uses submodules, so cloning requires a recursive submodule update, and running it requires the Arduino IDE version 1.6.x or later.