# ToneMask

> A precision noise and tone generator with independent left and right frequency control. You sweep a tone to find a frequency, then play white, pink or brown noise with a notch filter that removes a band centred on that frequency. Runs in the browser and installs as an app (PWA); everything is synthesized, so it works offline once installed.

Languages: English at https://tonemask.com/, Portuguese at https://tonemask.com/pt, Spanish at https://tonemask.com/es, German at https://tonemask.com/de. The app, checkout, licence page and backup email all follow the language the purchase started in.

ToneMask is a sound generator. It makes no medical or therapeutic claims, and it is not a hearing test.
Start with your volume low: high-frequency tones and noise are uncomfortable at volume.

## Free (no payment, no account)

- Tone finder: a continuous sweep from 500 Hz to 14,000 Hz to find your frequency.
- Notched playback: white noise with a 500 Hz-wide notch, both ears linked, plus a brown-noise bed and master volume.

## Lifetime — $29 USD, one-time payment

- Independent left and right frequency (a different notch centre for each ear).
- Adjustable notch width (100–2,000 Hz).
- Pink and brown noise carriers.
- Playback with the screen locked.
- No account and no subscription. The licence key is verified on the device, so it works offline, and the same key can be pasted on any of your devices.

## How to buy

- Open https://tonemask.com/ and press "Get Lifetime — $29" in the Licence section. Payment is by Stripe Checkout.
- Without JavaScript: POST a plain HTML form to `https://tonemask.com/api/checkout` (no fields needed); it answers with a 303 redirect to Stripe Checkout.
- Delivery: after payment you return to a page that shows your licence key and unlocks Lifetime on that device. The key is also emailed as a backup.

## Requirements

- A modern web browser on phone or desktop. Installing it to the home screen keeps it available offline.