# Introducing LUX Sidecar: Your SpeedCurve Companion

DevFeed: [Introducing LUX Sidecar: Your SpeedCurve Companion](<https://devfeed.tech/articles/introducing-lux-sidecar-your-speedcurve-companion-45691.md>)

Original publisher: [Read original article](<https://csswizardry.com/2026/08/introducing-lux-sidecar/>)

Author: Harry Roberts

Published: 2026-08-18T11:30:00Z

Content type: article

Language: en

Sources: [CSS Wizardry](<https://devfeed.tech/sources/css-wizardry.md>)

Topics: [real user monitoring](<https://devfeed.tech/topics/real-user-monitoring.md>), [browser](<https://devfeed.tech/topics/browser.md>), [navigation](<https://devfeed.tech/topics/navigation.md>), [Cache](<https://devfeed.tech/topics/cache.md>), [Network](<https://devfeed.tech/topics/network.md>), [Compression](<https://devfeed.tech/topics/compression.md>), [Monitoring](<https://devfeed.tech/topics/monitoring.md>), [HTTP](<https://devfeed.tech/topics/http.md>)

Tags: [browser](<https://devfeed.tech/tags/browser.md>), [cache](<https://devfeed.tech/tags/cache.md>), [measurement](<https://devfeed.tech/tags/measurement.md>), [monitoring](<https://devfeed.tech/tags/monitoring.md>), [network](<https://devfeed.tech/tags/network.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [performance](<https://devfeed.tech/tags/performance.md>), [rum](<https://devfeed.tech/tags/rum.md>)

## AI overview

LUX Sidecar is a SpeedCurve RUM plugin that adds browser and navigation context to real-user performance data, including network conditions, cache state, protocol, compression, service worker involvement, and navigation overhead. It sends supplemental custom data through the SpeedCurve API to help explain differences between page views.

## Source excerpt

LUX Sidecar is a small SpeedCurve RUM plugin that adds browser and navigation context to your real-user performance data.