How Twitch Caught Invisible Failures by Watching What Users See

From Blind Spots to Full Visibility in User Experience

Imagine you’re on Twitch, trying to gift your favorite streamer a three-month subscription. You click the button. Nothing happens. You try again. Still dead. You leave frustrated.

Meanwhile, Twitch’s backend dashboards are all green. No errors. No failed requests. Everything’s “healthy.” Except you just had a broken experience and they lost your purchase.

These are the exact moments that Twitch looked to avoid, so they built QoUX.

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🛠️ What Happened?

This problem started simple: users couldn’t click the multi-month gifting button. There were no backend errors because no requests ever fired. Backend-only monitoring was blind to the failure. Twitch only found out when enough users complained to support. By then, gifting revenue was down, and trust was eroded.

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🧠 Root Causes

Backend metrics alone weren’t enough. They show you if your systems work. They don’t show you if your product works for users. No client-side telemetry meant Twitch had no way to see if UI elements silently broke.

Client-side monitoring wasn’t trivial either. It brings huge data volumes. Millions of users clicking dozens of buttons every minute adds up fast. Privacy was another challenge – client telemetry has to handle user data carefully, especially when events include contextual details.

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🔎 The QoUX System

What is QoUX?

QoUX stands for Quality of User Experience. It’s Twitch’s client-first monitoring system that tracks real user interactions in real time. Instead of relying on backend requests alone, it captures what users actually do – clicks, navigations, purchase attempts – right from their devices.

⚙️ How It Works

Every client – web, mobile, console – emits events when a user interacts with key flows. These events aren’t basic logs. They include what was clicked, which funnel it was part of, browser version, device type, region, and an exact timestamp.