Online Shruti Box
A sruthi petti in your browser — set your Sa, switch on the drone notes and hold a continuous reed drone. Synthesized live, for riyaz and practice.
Press Space to turn the drone on or off. Tap any swara to add or remove it from the drone. Leave it holding while you practise.
Free online shruti box (sruthi petti) you can play in your browser
The Ajenza Online Shruti Box — also called a sruthi petti or shruti petti — is a free virtual drone box that plays entirely in your web browser, with no app, no sign-up and no downloads. Each note is a continuous, sustained reed voice synthesized live with the Web Audio API, with the gently beating detuned tone of a real harmonium-style shruti box. Set your Sa to any key (shown as a note name and Carnatic kaṭṭai number), switch on the swaras you want — Sa + Pa is the classic drone, or Sa + Ma, or any combination for your raga — and adjust the tone and volume. It pairs naturally with the tanpura and the tabla for a full practice setup.
Is the online shruti box free?
Yes — it is completely free, with no sign-up, no download and no watermark.
How is it different from a tanpura?
A shruti box holds a steady, continuous reed drone on the notes you switch on. A tanpura plucks its strings in a repeating cycle. Both give a reference drone.
How do I set my Sa?
Use the Sa slider; it shows the note name and kaṭṭai number, and all active drone notes retune instantly.
Which notes should I switch on?
Sa + Pa is the most common drone. Use Sa + Ma for ragas without Pa, or Sa alone, or any swaras your raga needs.
Do I need to install anything?
No. Sound is generated in the browser with the Web Audio API — nothing to install and no permissions required.
More free music tools: Online Harmonium · Online Tanpura · Online Tabla · Online Instruments