Live Reload: Test Your App Changes Instantly on Your Phone

Edit. Save. See it live.

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FeatureTestingLive ReloadUSB Debug

What is Live Reload?

Live Reload is Codular's real-time testing feature that pushes your builder changes directly to your installed Android app - without rebuilding the APK. Edit a text, change a color, add a component, and see it update on your phone within 2 seconds.

This is similar to React Native's Fast Refresh, but even better - it works with your actual installed APK, not a separate companion app.

How It Works

When Live Reload is enabled, Codular creates a direct connection between your builder and the installed app:

  • You edit something in the builder (text, style, component, flow)
  • Builder pushes the updated app definition to the server instantly
  • Your app polls the server every 1.5 seconds for changes
  • App detects a new version and re-renders with updated content

The entire cycle takes about 1-2 seconds from edit to seeing it on your phone.

Two Connection Modes

ModeConnectionSpeedBest For
USB ModePhone connected via USB cable~1 secondLocal development, fastest
WiFi ModePhone connected to internet~2 secondsRemote testing, no cable needed

The app automatically tries USB first (fastest), then falls back to WiFi/cloud mode.

Getting Started

Step 1: Build & Install Your App

First, you need an APK with Live Reload support:

  • Open your project in the Codular builder
  • Click Build to create an APK
  • Connect your phone via USB
  • Open USB Debug panel and click Install APK
  • Click Launch App

You only need to build once. After that, all changes sync live.

Step 2: Enable Live Reload

From the Test menu (recommended):
  • Click Test in the menu bar
  • Click Live Reload
  • The menu shows "Live Reload ON" when active
From USB Debug panel:
  • Open the USB Debug panel
  • Click the Live Reload button
  • It turns green when active

Step 3: Edit and Watch

Now just edit anything in the builder:

  • Change text content
  • Modify colors and styles
  • Add or remove components
  • Rearrange layouts
  • Update flow logic

Your phone updates automatically. No save needed, no rebuild needed.

USB Mode Setup

USB mode gives the fastest response time (~1 second) by creating a direct tunnel between your computer and phone.

Requirements

  • Android phone with USB Debugging enabled
  • USB cable connected to your computer
  • ADB installed on your computer

How USB Mode Works

Codular uses adb reverse to map your computer's API server (port 4000) to the phone's localhost. The app on your phone connects to localhost:4000 which tunnels back to your computer.

Phone (localhost:4000) <--USB tunnel--> Computer (API server:4000)

This happens automatically when you click Launch App or Live Reload in the USB Debug panel.

WiFi / Cloud Mode

WiFi mode works without any cable - your phone connects to the Codular server over the internet.

Requirements

  • Phone connected to WiFi or mobile data
  • App built and installed on the phone
  • Builder open at mobcraft.in

How WiFi Mode Works

The installed app tries USB first. If USB is not available (no cable), it falls back to the cloud server at mobcraft.in. The builder pushes changes to the server, and the app polls for updates.

Builder (mobcraft.in) --> Server (cloud) --> Phone (WiFi/data)

No setup needed - just enable Live Reload in the Test menu and it works.

Live Reload Indicator

When Live Reload is active, your app shows a small green "LIVE" badge in the top-right corner of the screen. This confirms the app is connected and receiving updates.

When you disconnect or disable Live Reload, the badge disappears and the app continues running with the last-received state.

What Updates Live?

FeatureLive Reload?
Text contentYes
Colors & stylesYes
Component add/removeYes
Layout changesYes
Flow logicYes
VariablesYes
Screen navigationYes
Background imagesYes
IconsYes
New screensYes (resets to home)
Native modules (camera, maps)Needs rebuild
App icon & splash screenNeeds rebuild
Package name changesNeeds rebuild

Comparison with Other Platforms

FeatureCodularKodularMIT App InventorThunkable
Live previewInstalled APKCompanion app onlyCompanion app onlyLive preview (web)
USB testingYesYes (companion)Yes (companion)No
WiFi testingYesNoNoYes (web only)
Tests real appYesNoNoNo
No companion neededYesNoNoN/A
Speed~2 seconds~3-5 seconds~3-5 seconds~1-2 seconds

Tips & Troubleshooting

App not updating?

  • Make sure Live Reload is enabled (green button in Test menu or USB panel)
  • Check that your phone has internet access (for WiFi mode)
  • For USB mode: ensure USB Debugging is enabled and cable is connected
  • Try clicking Launch App again to re-establish the connection

App shows "LIVE" badge but doesn't update?

  • The badge means the connection is active. Try making a change and waiting 2-3 seconds.
  • If still not updating, the builder may not be pushing changes. Close and reopen the USB Debug panel.

Want faster updates?

  • Use USB mode for the fastest response (~1 second)
  • Keep the builder tab focused (browser throttles background tabs)

Production apps

  • Live Reload does NOT affect production apps. When no server is reachable (2 second timeout), the app uses its bundled definition with zero delay.
  • The "LIVE" badge never appears in production.

Summary

Live Reload transforms your development workflow. Instead of the traditional build-install-test cycle (2-5 minutes), you get instant feedback (1-2 seconds). Build your app once, then iterate as fast as you can think.

Try it now at mobcraft.in!

C
Codular Team
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