Your audio never leaves your device.

Last updated: 2026-06-10

The short version

• The Burr listens to your grinder via your phone's microphone. Audio is processed locally and is never uploaded, recorded, stored, or shared. We have no servers that receive audio.
• Your grinder name, calibration data, and session history live in your browser's local storage and never leave your device. Clearing site data wipes them.
• We collect anonymous, aggregated usage analytics - which features get used, on what kind of device - to improve the app. No audio, no identity, no advertising trackers, no cross-site tracking.

What stays on your device

The Burr runs entirely in your browser. There is no account, no login, no cloud sync. The data the app uses to function - your grinder's name, its calibrated grams-per-second rate, your target dose, and your session log - is stored in your browser's localStorage and never leaves your device. The microphone audio is processed in real time and never recorded or transmitted. If you uninstall the app or clear site data, all of this is permanently deleted.

Usage analytics

To understand how the app is used and make it better, we collect a small amount of anonymous usage data. Specifically:

• Events: when the app is opened, when onboarding or calibration is completed, and when a grind is started or finished - including the target dose, the estimated grams, and how long the grind took. Numbers only, never audio.
• Anonymous IDs: a random identifier stored on your device and a per-session identifier. They are not linked to your name, email, or any account, and they are not shared with anyone.
• Context: which surface you're on (mobile web, desktop web, installed app, or Android app), your approximate country (derived from your IP - we don't store the IP), and basic device/browser type.

This is collected via our own first-party endpoint and via Cloudflare Web Analytics, which is cookieless and does not fingerprint or track you across other sites. We do not sell this data or use it for advertising. Your grinder's name and your microphone audio are never part of it.

Microphone access

The Burr requires your microphone to listen to your grinder. We use the Web Audio API to compute a real-time loudness reading from the microphone signal. The raw audio is never recorded to disk or transmitted.

You can revoke microphone permission at any time from your browser's site settings.

Service workers and offline use

The Burr is a Progressive Web App. After your first visit, the application code is cached locally so it works offline. The service worker only stores application assets - it does not store or transmit any of your data.

Hosting and connection logs

Our hosting provider (Cloudflare) may log standard request metadata (IP address, user agent, timestamp) when your browser downloads the app, as is normal for any website. We do not access, store, or analyze these logs ourselves. See Cloudflare's privacy policy for details.

Children's privacy

The Burr is intended for adult coffee enthusiasts. The usage analytics we collect are anonymous and not tied to any identity, and we do not knowingly collect personal information from anyone, including children.

Changes to this policy

If our practices change, we'll update this page and the "last updated" date above. Material changes will be announced in the app.

Contact

Questions: [email protected]