Privacy notice

Legal operator: Lemonergy
Address: Brussels

Lemonergy is local-first. Battery cells, imported measurements, missions, designs, simulation inputs, and engineering results remain in the browser or local application unless you deliberately export or share them. The account and billing service does not receive those engineering files.

Account and billing data

When you sign in, Lemonergy receives your account identifier and verified email address from the provider you choose: Google, Apple or GitHub, where available. Google and GitHub may also provide a display name and avatar URL. Apple may provide a private relay email address instead of your personal email. If you connect another sign-in option, Lemonergy stores its provider identifier and verified email on the same account. Accounts are not automatically merged because their email addresses match. Lemonergy stores a one-way hash of the session token and session expiry; it does not store your provider password or access tokens. Short-lived sign-in state is deleted after use or expiry. If you activate complimentary Pro, it also stores the start and expiry of that one-time offer. This does not create a Stripe customer or subscription. If you choose the card-required subscription trial, Stripe collects your card and billing details directly. Lemonergy does not receive or store full card numbers or card security codes. It stores Stripe customer, Checkout and subscription identifiers, the accepted terms version, trial start and expiry, subscription state and validity period, and webhook identifiers used to prevent duplicate processing.

Why it is processed

This information is used to authenticate you, provide the Free or Pro plan, manage complimentary access and any separately chosen subscription, prevent fraud and replay, answer support requests, and meet applicable accounting and legal duties. The sign-in provider you select handles authentication, and Cloudflare hosts the service and database. Stripe provides checkout and billing management for subscription trials and paid subscriptions.

Cookies and retention

Only strictly necessary authentication and OAuth-state cookies are set by Lemonergy. OAuth state expires after ten minutes and sessions after thirty days. Account and entitlement records are retained while the account is active and afterwards only for the period required for security, disputes, accounting, and applicable law.

Your choices and rights

You can sign out without changing local projects, cancel any paid subscription through Stripe's customer portal, and request access, correction, deletion, restriction, or portability where applicable. You may also object or complain to the competent data-protection authority. Contact info@lemonergy.com.

Last updated: 12 September 2026.