offline.observer
Free sounds, pure math. No samples, no recordings.
Built with Web Audio API. Listen, learn, download.
// categories
// featured sounds
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Crackling Campfire
Free campfire sound effect generated entirely with Web Audio API. Listen to a realistic synthesized crackling fire with deep roar and hissing gas, and download it as a WAV file for free.
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Thunder
Free thunder sound effect generated entirely with Web Audio API. Listen to a realistic synthesized thunderclap with rolling rumble, and download it as a WAV file for free.
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Ocean Waves
Free ocean wave sound effect generated entirely with Web Audio API. Listen to realistic synthesized sea waves with crashing foam and deep undertow, and download it as a WAV file for free.
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Wind Ambience
Free wind sound effect generated entirely with Web Audio API. Listen to a realistic synthesized wind ambiance with layered noise and LFO modulation, and download it as a WAV file for free.
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Babbling Brook
Free babbling brook sound effect generated entirely with Web Audio API. Listen to a realistic synthesized stream ambiance, learn how it's made with code, and download it as a WAV file for free.
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Rain Ambience
Free rain sound effect generated entirely with Web Audio API. Listen to a realistic synthesized rain ambiance, learn how it's made with code, and download it as a WAV file for free.
// recent sounds
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Error Buzzer
Free error buzzer sound effect generated entirely with Tone.js and Web Audio API. Listen to a synthesized descending warning tone, learn why it signals danger, and download it as a WAV file for free.
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Notification Chime
Free notification chime sound effect generated entirely with Tone.js and Web Audio API. Listen to a pleasant ascending triad, learn the music theory behind alert sounds, and download it as a WAV file for free.
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UI Click
Free UI click sound effect generated entirely with Tone.js and Web Audio API. Listen to a crisp synthesized click, learn how transient sounds work, and download it as a WAV file for free.
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Brown Noise
Free brown noise sound effect generated entirely with Tone.js and Web Audio API. Listen to deep synthesized brown noise, learn about Brownian motion audio, and download it as a WAV file for free.
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Pink Noise
Free pink noise sound effect generated entirely with Tone.js and Web Audio API. Listen to synthesized 1/f pink noise, learn the science behind it, and download it as a WAV file for free.
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Emergency Siren
Free emergency siren sound effect generated entirely with Web Audio API. Listen to a synthesized siren sound, learn how it's made with Tone.js, and download it as a WAV file for free.
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Synth Pad
Free ambient synth pad sound effect generated entirely with Web Audio API. Listen to a warm synthesized pad sound, learn how it's made with Tone.js, and download it as a WAV file for free.
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White Noise
Free white noise sound effect generated entirely with Tone.js and Web Audio API. Listen to pure synthesized white noise, learn how it works, and download it as a WAV file for free.
All sounds are generated with Web Audio API — no samples, just code.