Last updated: 9 August 2026
Home Theater Maestro ("HTM", "the app") is private by design. In short: HTM keeps your data on your device and does not track you. The only exception is the purchase and activation of a Pro licence, detailed in a dedicated section below. This page explains what that means in practice.
In one sentence
All of HTM's computation runs locally on your device, offline: no account, no ads, no usage analytics and no telemetry. The only exception is the purchase and activation of an optional Pro licence, which involve our licensing server (see the dedicated section below). The free app needs no connection at all.
Data you create in the app
Your projects (room dimensions, speaker placement, imported measurements, settings, the optional brand of your hardware) are stored locally only on your device (browser / app storage). They never leave your device and are accessible only to you.
- You can export or delete them at any time from the app.
- Uninstalling the app or clearing its data erases this information.
- HTM performs no cloud backup.
Files you import
Files you import (REW measurements, .ady calibration files, ColorHCFR .chc measurements, 3D models) are processed locally and are never uploaded. The device model that an .ady file may contain is read internally but never displayed or logged, in line with the tool's brand-neutral nature.
Outbound communication: the "Contact support" button
Apart from Pro licence activation (described below), the only time HTM can transmit anything is when you click "Contact support" yourself (or from an error screen). This button opens your mail client with a pre-filled message that you can see, edit, and cancel before anything is sent. HTM never sends any email automatically.
To help diagnose issues, the draft contains: the HTM version, the build number, your browser (user agent), the active page, and, on a crash, the technical error message. It includes no project data, no measurements, no settings. Any strings that look like API keys are stripped from the text before the message is built.
Pro licence: purchase and activation
HTM is free; an optional Pro licence unlocks advanced features. Unlike the rest of the app, purchasing and activating a Pro licence involve a server, this is the only part of HTM that is not offline.
- Purchase (on our website): payment is handled by Stripe (payment provider). After the purchase, our licensing server stores your email address, the licence key issued, and the transaction references (Stripe identifiers), in order to deliver the key by email, issue the invoice (legal obligation) and handle any refund. We never see your card number: it stays with Stripe.
- Activation (in the app): on first activation, the app contacts our server, transmitting the key and an anonymous (hashed) device fingerprint, never your identity, never your projects. That fingerprint is used solely to limit activation to two devices and to prevent abusive sharing. After that, the app works offline again; an occasional re-check happens when a connection is available.
Controller, retention, rights. This data is processed by WM STUDIOS to perform the licence contract, to meet the legal invoicing obligation, and for our legitimate interest in preventing abuse. It is kept for the lifetime of the licence and for the applicable legal retention periods (invoicing). You have the rights of access, rectification and erasure: via "Contact support" or the Legal notice page.
Permissions
HTM requests no location, contacts, camera, or microphone permissions, and drives no measurement device. Video calibration works by file import: you measure with ColorHCFR, then import the .chc file into HTM: no probe access, no data sent anywhere.
On Android, the app declares a single permission, INTERNET: it is a technical permission required by the WebView container (Capacitor) to display the interface, and it also serves, where applicable, the activation of a Pro licence (see "Pro licence: purchase and activation"). Apart from that case and the "Contact support" button, the app makes no outbound requests.
Audience measurement on this website
The section above describes the app. This website, on the other hand, counts its page views, its downloads and the time spent per page, so we know what gets read and in which languages. That measurement is cookieless and has no visitor identifier: we count events, not people.
What is recorded, and nothing else: the page visited, the file downloaded and its version, the time spent on the page, your browser language reduced to a two-letter code, and the country when our host provides it. We record no IP address, neither in the clear nor hashed, no cookie, no browser fingerprint and no session identifier. The country is never derived from an IP address. There is therefore no such thing as a "unique visitor" here, and none of these rows can be tied back to a person.
These counters are hosted on our own servers, with no third-party measurement tool. Detail is kept for at most 24 months; beyond that only monthly totals remain. No consent is required for this strictly anonymous measurement, and turning off JavaScript is enough not to be counted at all.
Third-party services
The app embeds no third-party data-collection SDK (no Google Analytics, Firebase, Sentry, ad network, etc.). The only third party involved is Stripe, solely when purchasing a Pro licence on the website (payment processing), see the "Pro licence" section. Links to external resources (standards bodies, community tools) open your browser; those sites have their own policies.
Children
HTM is not directed at children and knowingly collects no data about them.
Your rights
For the app itself, no personal data is collected or transmitted: your projects live on your device and you can erase them yourself. The only server-side data concerns the purchase and activation of a Pro licence (see the dedicated section), there you have the rights of access, rectification and erasure.
Changes to this policy
This policy may evolve as the app changes. The "last updated" date at the top is authoritative. Notable changes will be noted in the app's version history.
Contact
App publisher and responsible party: WM STUDIOS (61 rue de Lyon, 75012 Paris, France). The free app performs no processing of personal data; the only processing within the meaning of the GDPR concerns the purchase and activation of a Pro licence, described above (controller: WM STUDIOS).
For any privacy question, use the "Contact support" button in Settings → About, or reach us via the Legal notice page.