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Pre-call Testing and Diagnostics


Twilio provides the following tools for understanding clients' connections and diagnosing any potential problems before, during, or after a Video call.


Video Diagnostics Application

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The Twilio Video Diagnostics Application(link takes you to an external page) is an open-source ReactJS application that tests participants' device and software setup, connectivity with the Twilio Cloud, and network performance. It uses Twilio's RTC Diagnostics SDK and Preflight API to provide end-users feedback about their network quality and device setup and also includes recommendations for improving their video call quality.

GIF showing examples of how the Video Diagnostics app can be used.

You can learn more about the Video Diagnostics App in the blog post(link takes you to an external page) or by visiting the README(link takes you to an external page).

The RTC Diagnostics SDK and Preflight API can also be used independently in your application to test your participants' device setup and network connectivity.


Twilio's RTC Diagnostics SDK(link takes you to an external page) for JavaScript applications provides functions to test a participant's input and output devices, including microphones, speakers, and cameras, as well as functionality to confirm that a participant meets the network bandwidth requirements required to make a voice call or conduct a video call.

This is a general WebRTC SDK and does not rely on Twilio infrastructure. You can incorporate it into your applications for pre-call testing or troubleshooting user issues during a call.


The Preflight API, available in versions 2.16.0 and above of the Twilio Video JavaScript SDK, provides functions for testing connectivity to the Twilio Cloud. The API can identify signaling and media connectivity issues and provide a report at the end of the test.

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