The edge of a wood just after dusk, with fireflies drifting over the grass. Each one is an oscillator with its own natural rhythm, and every flash nudges the phase of the flies near it, so patches of the meadow drift into step and out again — nothing is scripted. Three painted tree lines with mist between them give it depth: far flies are small, dim and slow and pass behind the grass, near ones are bigger, brighter and quicker and pass in front of it.
Natural rhythms run from 3.2 to 5.5 seconds, and each flash pulls the phase of nearby flies toward its own. Setting sync to 0 turns the coupling off and every fly keeps its own clock — a quick way to see what the pulling is doing.
Self-hosted, read-only container. Fireflies draws on a single 2D canvas — no WebGL, and no network request of any kind. The backdrop is painted once; each frame redraws only the grass and the lights, at a capped 30 frames a second.
A count of flies, a colour — gold, green, or blue — and dusk or night. Scene scale comes from the screen’s shorter side, so the same URL works on a 16:9 panel, a portrait tablet, or a browser window.
Setup
A browser is genuinely enough — the Mac app and Fully Kiosk below are conveniences, not requirements.
F11 on Windows and Linux, ⌃⌘F on macOS.chrome --kiosk <url> — on macOS, open -a "Google Chrome" --args --kiosk <url>.Displays are ordinary web pages, so anything that can hold one open works: a Raspberry Pi on a monitor, a retired iPad, a Fire tablet, the browser built into a TV.
Configuration
Everything below, plus a live preview and a URL builder that writes the link for you, is at fireflies.livingkiosk.com/setup.
| Parameter | Default | Meaning |
|---|---|---|
count | 70 | How many fireflies are in the meadow, 5–250. Rounded to a whole number. |
sync | 0.5 | How strongly each flash pulls on nearby flies’ rhythm, 0–1. 0 turns it off. |
hue | gold | green or blue. The colour of the light. |
time | dusk | night. Dusk keeps a rose and lilac afterglow on the horizon; night is nearly black-blue with a full field of stars. |
speed | 1 | A multiplier on drift, flash rhythm and grass, 0.2–3. Clamped, not rejected. |
dim | 0 | Neutral darkening overlay, 0–0.8 (fleet-wide convention). |
seed | — | Pins the trees, stars, grass, and each fly’s starting position and phase, so the same URL always begins the same way. |
Fireflies is open source under the MIT licence. Run it yourself with one command. The source opens to the public soon.