Privacy Policy — PrivyMermaid (macOS)

Last updated: August 8, 2026

This policy explains how PrivyMermaid for macOS (the “App”) handles information. The App is local-first: its editor, preview, and local AI engine work without an account or a PrivyMermaid server. Some optional features use network services only when you choose to use them; those features are described below.

1. Summary

• No advertising, analytics, tracking SDKs, or developer crash-reporting service are included in the App.
• Mermaid and D2 rendering runs locally from bundled resources.
• Diagrams and App data are stored locally unless you use Diagram Cloud or send content to an AI endpoint.
• You control whether to configure AI, download a Built-in Engine model, sign in to Diagram Cloud, or sync content.

2. Data Stored on Your Mac

The App stores the following data locally in ~/Library/Application Support/PrivyMermaidMac/:

• Diagram names, source code, language, groups, and local metadata
• Editable AI prompt templates and per-diagram AI chat conversations
• App and preview preferences, AI provider settings, configured endpoints, model settings, and any API key you enter
• Downloaded Built-in Engine model files, if you choose to download them

The App also stores local-to-cloud document links in macOS preferences. If you sign in to Diagram Cloud, the authentication provider securely persists its session credentials in the macOS Keychain. PrivyMermaid does not transmit this local data unless you use one of the optional network features below.

3. Local Processing and File Access

• Rendering: Mermaid and D2 source is compiled and rendered on your Mac. The App does not use a cloud rendering service.
• Built-in Engine: After a model is downloaded, local AI inference runs on your Mac. Diagram content and chat prompts are not sent to an AI server by this engine.
• Import and export: The App reads or writes a file only after you choose it in a macOS open or save panel. Exported files and copied preview images go only to the location or clipboard you select.

4. Optional AI Providers

You may configure Ollama, LM Studio, or another OpenAI-compatible endpoint. When you submit an AI request, the App sends the request content directly to the endpoint you chose. Depending on the action, this can include your diagram source, prompts, chat messages, selected model settings, and—only when you turn on image attachment—a rendered PNG of the diagram. Any API key you configure is sent only to that endpoint for authentication.

Local endpoints such as Ollama or LM Studio can run entirely on your Mac. A remote endpoint is governed by its own privacy policy and data practices. PrivyMermaid does not relay AI requests through a PrivyMermaid server.

5. Built-in Model Downloads and Purchases

If you choose to download a Built-in Engine model, the App downloads the model package directly from Hugging Face and stores it locally. Hugging Face may receive standard network information associated with that download, such as your IP address and request metadata, under its own privacy policy. A one-time PrivyMermaid Pro purchase or restore is processed by Apple through StoreKit; the App receives the purchase entitlement needed to unlock Pro features.

6. Diagram Cloud

Diagram Cloud is optional. Opening its public template library sends requests to Diagram Cloud to retrieve the templates you browse and any search terms you enter. You can use the rest of the App without opening Diagram Cloud or creating an account.

If you sign in with GitHub, Google, or an email link, Supabase processes the authentication flow and the App receives a session and account identifier. When you use cloud features, Diagram Cloud stores and processes the data necessary to provide them: your account identity, template follows, project and template metadata, and the names, languages, and source code of diagrams or templates you choose to publish or sync.

For signed-in users, a successfully saved local diagram may be queued for a delayed sync to the default cloud project. Local saving happens first; a network or server error does not replace, delete, or prevent local work. Deleting a cloud diagram from the App deletes only its cloud copy, not the local diagram.

7. Data Sharing

We do not sell your information or share it for advertising. The App sends data only as needed for the optional services you invoke: your configured AI provider, Hugging Face for a model download, Apple for a purchase, and Diagram Cloud and Supabase for cloud authentication and features. Those providers process data under their own terms and privacy policies.

8. Your Choices and Deletion

• Use the App offline and leave AI providers and Diagram Cloud unconfigured.
• Delete diagrams and conversations in the App, or remove its Application Support folder to delete local App data and downloaded models.
• Sign out of Diagram Cloud to remove the local session, and delete cloud diagrams from the Projects view when desired.
• Choose a different AI provider, remove its API key from Settings, or disable image attachment at any time.

9. Children’s Privacy

The App does not knowingly collect personal information from children. Diagram Cloud and third-party AI providers may have their own age or account requirements.

10. Changes and Contact

We may revise this policy when the App or its services change. The date above will be updated when we do. For privacy questions, contact [email protected].

PrivyMermaid is a local-first macOS application for Mermaid and D2 diagrams, with optional AI and Diagram Cloud features.