Sync Theme

Sync Theme keeps Gmail, Grafana, and Slack in step with your operating system's light/dark setting. Flip your OS to dark mode and your open Gmail, Grafana, and Slack tabs follow automatically — and back to light when you switch back.

Features • Works on Gmail, Grafana (Grafana Cloud and self-hosted), and Slack web. • A master on/off switch plus a per-site toggle, so you can run just the sites you want. • Add self-hosted Grafana instances on your own domains — you approve each one through Firefox's permission prompt. • No accounts, no tracking, no data collection, no remote servers.

How it works When your OS theme changes, Sync Theme switches each site using that site's own built-in light/dark control, so it looks exactly as the site intends — including custom Slack workspace themes. It runs only on Gmail, Grafana, and Slack, never on other sites, unless you explicitly add a self-hosted Grafana domain on the options page.

Privacy Sync Theme does not collect, transmit, or sell any data. Your on/off preferences sync through your own Firefox account; any self-hosted domains you add stay on your device. Full policy: https://github.com/sideprojects-dee/sync-theme/blob/main/PRIVACY.md