Eternal Nebula is a free browser focus space with a focus timer (15, 25 and 50 minute presets, custom length, breaks and a fullscreen focus mode) and a mixer of 17 recorded sounds. Layer up to 4 sounds with per-layer volume and use a sleep timer that fades them out. Mixes save in the browser, with optional account sync, and recordings can be downloaded for offline listening in supported browsers.
The site also has a solar system explorer, an ADHD focus room, sound and focus guides, and three games (Constellation Drift, Nebula Run and Nebula Patrol). All 17 recordings, 4-sound mixing, timers and saved mixes are free with no daily limit, and no account is required. It runs in desktop and mobile browsers.
Eternal Nebula was built to be a calm, free place to focus: one task at a time, a simple timer, and recorded sounds you can mix your way.