What we collect
Almost nothing. A Pro licence bought on this website is a key: activating or revalidating it sends Dodo Payments the key and a device name, and if you never activate one, that request never happens. A Pro purchase made in the App Store is handled entirely by Apple — the app asks the App Store whether a valid purchase exists, and that conversation is between the app and Apple. The update check asks mernyx.com for a version number. That is the whole list.
The direct download checks for updates with Sparkle: a small signed feed file from mernyx.com, once a day and whenever you pick Check for Updates, carrying nothing beyond the request itself. Accepted updates download from releases.mernyx.com, and the signature is verified before anything is installed. A build from the App Store updates through the App Store instead, and never asks mernyx.com for an update.
The app carries no analytics SDK, no crash reporter and no advertising identifier; this website sets no cookies and embeds no third-party scripts or fonts. It does keep one thing in your browser's local storage — the language you chose on this site — and it never leaves your machine. Apple separately collects App Store install and crash information under its own policy and your device settings — that is Apple's collection, not the app's.
What we don't collect
Files you open, edit, render or export are read and written locally. No file contents, file names, document history or exported images are uploaded anywhere. The Quick Look extensions that preview .mmd files in Finder do not link a networking library at all — they cannot send anything even in principle.
Settings — appearance, editor font, canvas options, AI connections and model choice — live in macOS preferences on that Mac, and nothing syncs them anywhere.
The AI feature — the one exception
Mernyx can generate and repair diagrams with a large language model, and it is bring-your-own-key: you configure an OpenAI-compatible endpoint and supply your own API key. That endpoint is yours, not ours, and requests go from your Mac straight to it.
When you press Generate or Fix, the app sends that provider the prompt; Fix also sends the whole document source, because the model cannot repair what it cannot read. That is the only time diagram content leaves your Mac, it happens only when you press the button, and it goes to a provider you chose under their privacy policy.
Third-party services
Depending on what you use, these parties are involved, each under its own policy:
- Dodo Payments — only for a purchase on this website: checkout, payment, receipts, tax, refunds and licence-key delivery. It is the merchant of record, and we never see your card or billing details.
- Apple — only if you bought Pro in the App Store. Apple takes the payment, issues the receipt, calculates tax and handles refunds; the app learns only whether a valid purchase exists.
- Google Analytics — this website uses Google Analytics to count visits, and Google processes that website analytics data under its own privacy policy. The app contains no Google Analytics.
Data storage
Your API key, your licence key and its validation cache live in the macOS Keychain. An App Store purchase lives with Apple instead — the app keeps no record of it. Nothing is written to plain-text preferences, and Mernyx keeps no copy of your AI traffic.
Your rights
We do not create an account or a profile for you. If you email us, we hold that message and your address only for as long as it takes to answer. There is otherwise nothing for us to export, correct or delete. If you believe we do hold something, email hi@mernyx.com and we will look, and we will respond within 30 days.
For purchase records, receipts and refunds, the seller is the data controller: Dodo Payments for a purchase on this website, Apple for a purchase in the App Store — and both hold that data under their own privacy policies. In the EU/EEA or the UK, you also have the rights GDPR gives you, including data portability and the right to complain to your local data protection authority. Mernyx is a developer tool, not directed at children, and we do not knowingly collect personal data from anyone.
Contact
For privacy questions, email hi@mernyx.com. If the app ever gains a feature that sends data anywhere new, this page changes in the same release that ships it. The date at the top is the date of the current version.