MusicBook Pro is developed by Music by Lars. It is a private songwriting, personal songbook, setlist and live-performance app for original songs and user-entered material.
Summary
MusicBook Pro does not use ads, subscriptions, third-party tracking or third-party analytics. Built-in Smart and audio features do not use third-party AI or audio APIs. The optional Mac-only Agent Collaboration feature can send only permitted text and metadata to a provider such as OpenAI or Anthropic after the user deliberately enables access.
Your creative library is stored locally by default. Optional iCloud sync uses your private iCloud account when you enable it. MusicBook Pro uses Apple StoreKit for the optional one-time Full Version unlock.
Data stored in the app
MusicBook Pro may store songs, drafts, ideas, setlists, collections, lyrics, chords, tags, musical and performance metadata, notes, app settings, recordings you deliberately save and temporary transcription audio on your device. Per-device Agent Collaboration settings include permissions, access expiry and a local activity history containing provider, action, item name and time, but not lyrics or raw request text.
iCloud sync
iCloud sync is optional. When enabled, supported song data is synchronized through your private iCloud account. Ideas media, raw audio and temporary transcription audio do not sync by default. Agent-created Ideas and Setlists follow the same song-data sync choice as other saved library items.
Microphone, speech recognition and camera
MusicBook Pro requests microphone access only for recording your own ideas or using transcription features, speech-recognition access only to create editable text from your own recordings, and camera access only for user-initiated scanning or video Ideas. Apple system speech recognition may process audio according to Apple's platform behavior and your device settings. MusicBook Pro does not send audio to third-party transcription services.
Built-in Smart features
SmartRhymes, SmartFeedback, SmartImport, SmartSetlist, SmartScroll and Chord Inspiration are designed to work locally or through Apple-native/on-device technologies where available. These built-in features do not send songs, lyrics, chords, recordings or profile text to third-party AI services. Agent Collaboration is a separate optional feature.
Agent Collaboration
Agent Collaboration is off by default and its controls are available only in the Mac version. Other devices show only a short explanation. When enabling it, the user chooses whether a connected service may read approved library text and metadata, create new Ideas, create new Setlists, or a combination of those actions. The user chooses a manual access duration, with an encouragement to keep it as short as practical, or selects Until turned off. Timed access does not extend when used. Disconnecting or turning access off revokes the Mac connection.
The authenticated MCP gateway runs on Cloudflare Workers and relays approved requests to the paired Mac. Auth0 provides OAuth login and access tokens. The gateway is designed without a creative-library database and without raw request-body, lyric or item-content logging. Approved content necessarily passes through the gateway and the chosen agent provider to answer the request. Cloudflare and Auth0 may process ordinary network, security and authentication data under their own terms and privacy policies.
If the Mac is closed, offline or access is disabled, the private library is unavailable. Connected agents cannot access source code, generic files, shell commands, Git, Xcode, SQL, media, temporary recordings, hidden transcripts, credentials or recovery data. They cannot edit or delete existing library items. With the matching permission enabled, they may save only a new Idea or Setlist through MusicBook Pro's normal persistence boundary. The local activity history provides Open and Undo controls for agent-created items and is not synced by default.
OpenAI review sandbox
OpenAI's app review receives a dedicated reviewer login that is isolated from every MusicBook Pro user's Mac and library. It exposes only fictional original sample Songs, Ideas, Projects and Setlists supplied by Music by Lars. Review-created Ideas and Setlists are kept only in volatile gateway memory and may disappear when the service restarts. The reviewer login cannot reveal or modify a user's creative content.
Agent Collaboration retention
For normal user accounts, approved request content is retained by the MusicBook Pro gateway only while the request is being relayed and until a response or the gateway timeout, normally no longer than 25 seconds. Active WebSocket routing state remains only while the Mac is connected and is discarded on disconnect or service restart. Pairing codes are short-lived; signed reconnect tokens remain on the user's Mac until revoked or replaced. The gateway does not persist raw request content or a copy of the creative library.
Auth0 retains reviewer and user authentication records, security events and token-related data under the configured Auth0 account and Auth0's policies. OpenAI, Anthropic, Cloudflare and Auth0 may retain their own service, security or conversation data under their respective policies and account settings. Users may revoke MusicBook Pro access from the Mac at any time and may contact Music by Lars to request deletion of a MusicBook-specific Auth0 login.
OpenAI and Anthropic data controls
Provider settings apply after content is sent to that provider. MusicBook Pro cannot change them for you. Review the current provider policy before sharing private writing.
- Personal ChatGPT accounts: open Profile → Settings → Data Controls and turn off Improve the model for everyone. OpenAI states that new personal-workspace conversations are then excluded from model training. OpenAI states that ChatGPT Business, Enterprise, Edu and API inputs and outputs are not used for training by default. OpenAI data-control guide.
- Consumer Claude accounts: open Settings → Privacy and turn off the model-improvement sharing option if it is enabled. Anthropic states that consumer chats and coding sessions may be used to improve Claude when the user allows it, when material is submitted as feedback, or in certain safety-review cases. Anthropic consumer data guide.
- Claude for Work and Anthropic API: Anthropic states that inputs and outputs are not used for model training by default unless the customer explicitly opts in or submits material as feedback. Anthropic commercial data guide.
Submitting thumbs-up/down feedback may share the related conversation with the provider under its feedback policy. Avoid sharing credentials, recovery information or content that you do not want the selected provider to process.
Backups and exports
MusicBook Pro creates a backup or export only when you request one. Ideas media is excluded by default unless you explicitly choose an option that includes it.
What Music by Lars collects
MusicBook Pro does not create a developer-controlled copy of your creative library. The optional gateway processes an Auth0 subject identifier, requested OAuth scopes, active connection state and in-flight approved requests solely to authenticate and relay requests to the paired Mac. If you contact Music by Lars, your message and contact details are handled only so we can respond.
Tracking and children
MusicBook Pro does not track you across apps or websites and is not designed to collect personal information from children.
Contact
For privacy or support questions, contact Music by Lars at musicbylars.com/index.php/contact.