Use Flashlight to Monitor Activity

Open Beta Documentation Amazon offers this technical documentation as part of a pre-release, open beta. The features described might change as Amazon receives feedback and iterates on the features. For the most current feature information, see the Release Notes.

Flashlight is an open-source performance monitoring tool. For Vega apps, it monitors CPU and memory performance data. Frames per second (FPS) monitoring is for inclusion in future releases. Flashlight with Vega works only on macOS and Linux.

This page explains how to setup and use Flashlight with Fire TV Stick device and Vega Virtual Device simulator).

Prerequisites

Make sure you complete the following:

Install Flashlight

Download Flashlight:
Extract to flashlight directory:
Copied to clipboard.
```
unzip flashlight-kepler-e0ad4ee.zip -d ~/flashlight
```
Build using yarn:
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```
cd ~/flashlight/flashlight-private-kepler-secret
```
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```
yarn
```
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```
yarn build
```

Run Flashlight

Launch your sideloaded app on Fire TV Stick or Vega Virtual Device.
Navigate to Flashlight directory:
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```
cd ~/flashlight/flashlight-private-kepler-secret
```

Run measure command to start Flashlight web interface.

For Vega Virtual Device:

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PLATFORM=keplersimulator node packages/commands/measure/dist/server/bin.js measure

For Fire TV Stick:

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PLATFORM=keplerdevice node packages/commands/measure/dist/server/bin.js measure

In the Flashlight web interface, do the following:
- Click the Auto Detect to find your app's package ID.
- Click the Start Measuring to begin monitoring.
Important: Flashlight works only with sideloaded apps, not system apps.

Watch how to use Flashlight

The following video shows how to use Flashlight with VegaVideoApp on a Fire TV device:

Build, sideload, and launch VegaVideoApp on Fire TV.
Use Flashlight to monitor VegaVideoApp's live performance.

Demo of Flashlight monitoring on Fire TV device

Last updated: Sep 30, 2025

Use Flashlight to Monitor Activity

Prerequisites

Install Flashlight

Run Flashlight

Watch how to use Flashlight

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