About
// about offline.observer
Every sound in the world is a combination of frequencies. We synthesize them in your browser using nothing but code and math. No samples, no recordings — just pure signal processing.
Listen to any sound, learn how it’s made, and download it for free.
// open source stack
This project is built entirely with open source technologies. Here’s what powers offline.observer:
Core
| Technology | Description | License |
|---|---|---|
| Astro | Static site framework — blazing fast, zero JS by default | MIT |
| Tone.js | Web Audio framework for interactive music in the browser | MIT |
| Web Audio API | Browser-native audio synthesis engine | W3C Standard |
Styling & UI
| Technology | Description | License |
|---|---|---|
| Tailwind CSS | Utility-first CSS framework | MIT |
| AstroPaper | Minimal, SEO-friendly Astro blog theme (our base template) | MIT |
Search & Build
| Technology | Description | License |
|---|---|---|
| Pagefind | Static search library — fast, lightweight, no server needed | MIT |
| TypeScript | Typed JavaScript | Apache-2.0 |
| Vite | Next-gen frontend build tool | MIT |
Audio Libraries (available for future sounds)
| Technology | Description | License |
|---|---|---|
| Tone.js | Synths, effects, sequencing, transport | MIT |
| Wad | Web Audio DAW — jQuery for your ears | MIT |
| XSound | Synthesizer, effects, visualization, recording | MIT |
Fonts
| Font | Description | License |
|---|---|---|
| Google Sans Code | Monospace font — retro terminal aesthetic | Open Font License |
// how sounds are made
All sounds on this site are synthesized in real-time inside your browser using the Web Audio API and Tone.js.
The basic building blocks:
Oscillator → Filter → Gain → Destination (your speakers)
↑ ↑ ↑
waveform frequency volume
(sine, (lowpass, (envelope,
square, bandpass, LFO)
saw, highpass)
triangle)By combining oscillators, noise generators, filters, and effects — we can recreate virtually any sound that exists in the physical world.
Every sound page includes a full explanation of how that specific sound is synthesized, along with the code to make it yourself.
// license
All sounds generated on this site are free to use for personal and commercial projects. The sound files you download are yours — no attribution required.
The site’s source code is based on AstroPaper (MIT License).