Kivy Reloader
Hot reload your Kivy app on multiple Android phones, emulators and computer at the same time, in real‑time.
This tool allows you to instantly update your Kivy app on multiple devices simultaneously by pressing Ctrl + S, without having to restart / recompile every time you make a change, saving your precious development time and effort.
It uses Kaki (file watching via watchdog) under the hood and a small Trio server on-device to receive file updates.
Check out the 📚 Kivy School tutorial to learn how to use this tool, or follow the documentation below.
- 📚 Full docs: https://kivyschool.com/kivy-reloader/
- Install: https://kivyschool.com/kivy-reloader/installation/
- How to use: https://kivyschool.com/kivy-reloader/how-to-use/
Quickstart
1) Install the toolchain + helpers
Pick your OS and run the one‑liners below. These scripts set up the Android toolchain, uv, Buildozer deps, scrcpy, bundletool, etc.
Linux
curl -LsSf https://kivyschool.com/kivy-android-ubuntu.sh | bash
macOS
After installing Homebrew, close & reopen the terminal so
brewis in PATH.
# Install Homebrew (if needed)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
# System deps + OpenJDK 17 and symlink so macOS tools can find it
brew install android-platform-tools openjdk@17 autoconf automake libtool pkg-config cmake openssl
sudo ln -sfn /opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk \
/Library/Java/JavaVirtualMachines/openjdk-17.jdk
# Kivy Reloader setup
curl -LsSf https://kivyschool.com/kivy-android-macos.sh | sh
Windows
Run PowerShell as Administrator:
# Base setup (scrcpy + adb init)
powershell -ExecutionPolicy ByPass -c "irm https://kivyschool.com/kivy-android-windows.ps1 | iex"
# Install WSL2 + Ubuntu 24.04
wsl --install -d Ubuntu-24.04
Then, inside the new Ubuntu terminal:
curl -LsSf https://kivyschool.com/kivy-android-wsl2.sh | bash
2) Create a tiny demo project (pick one)
Beginner (single file)
mkdir kivyschool-hello
cd kivyschool-hello
uv init
uv add "kivy-reloader[desktop]"
Project tree:
kivyschool-hello
├── main.py
├── pyproject.toml
├── README.md
└── uv.lock
main.py
import trio
from kivy.lang import Builder
from kivy_reloader.app import App
kv = """
Button:
text: "Hello World"
"""
class MainApp(App):
def build(self):
return Builder.load_string(kv)
app = MainApp()
trio.run(app.async_run, "trio")
Advanced (recommended package structure)
mkdir -p kivyschool-hello/hello_world/screens
cd kivyschool-hello
uv init
uv add "kivy-reloader[desktop]"
Project tree:
kivyschool-hello
├── hello_world
│ ├── app.py
│ └── screens
│ ├── main_screen.py
│ └── main_screen.kv
├── main.py
├── pyproject.toml
├── README.md
└── uv.lock
main.py
import trio
from hello_world import HelloWorldApp
app = HelloWorldApp()
trio.run(app.async_run, "trio")
hello_world/app.py
from kivy_reloader.app import App
from hello_world.screens.main_screen import MainScreen
class HelloWorldApp(App):
def build(self):
return MainScreen()
hello_world/screens/main_screen.kv
<MainScreen>:
BoxLayout:
orientation: "vertical"
Button:
text: "Welcome to Kivy Reloader!"
hello_world/screens/main_screen.py
from kivy.uix.screenmanager import Screen
from kivy_reloader.lang import Builder
Builder.load_file(__file__)
class MainScreen(Screen):
pass
3) Initialize Kivy Reloader in your project
uv run kivy-reloader init
This creates kivy-reloader.toml (config) and a minimal buildozer.spec.
Minimal config example:
[kivy_reloader]
HOT_RELOAD_ON_PHONE = true
FULL_RELOAD_FILES = ["main.py"]
WATCHED_FOLDERS_RECURSIVELY = ["."]
STREAM_USING = "USB" # or "WIFI" (requires initial cable setup)
Usage
Step 1 — Run on your computer
uv run main.py
This starts your app and the reloader background watcher.
Step 2 — Deploy to Android
uv run kivy-reloader run
Select the first option to build + install the APK via Buildozer. Once running on your phone, hot reload is already active.
Step 3 — Develop with hot reload ♻️
When you save a watched file:
- If it matches
FULL_RELOAD_FILES→ the app restarts on computer and device(s). - If it's inside
WATCHED_FOLDERS_RECURSIVELY,WATCHED_FOLDERSor named inWATCHED_FILES→ the app hot reloads. - With
HOT_RELOAD_ON_PHONE = falseonly your desktop app reloads/restarts.
How it works (high level)
- Watches files using watchdog (via Kaki).
- On change, syncs files and signals your app(s) to reload.
- An on‑device Trio server receives files during development for instant updates.
Contribution
Have ideas or found a bug? Please open an issue or a pull request.
Need help?
Come say hi in the Kivy Discord support channels — we're happy to help!
2 maintainers
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