Privacy Policy

About this policy

Lenskit is operated by Helium GK in Japan. This policy explains how we handle information when you create, analyze, save, and share optical systems using Lenskit.

Account and authentication information

We store your email address, username, account identifiers, verification status, and account dates. Depending on your sign-in methods, we store password hashes, passkey public keys and credential metadata, or Google account connection information. We do not receive your Google password or your passkey’s private key. Sessions may include IP addresses and browser information.

Google sign-in

If you choose Google sign-in, we request OpenID, email, and profile permissions. Google may provide your account identifier, email address, verification status, name, and profile image. We handle authentication tokens associated with this connection. We use this information to authenticate you, create or recognize your account, and protect account access. We do not request Gmail messages, Drive files, contacts, or calendars, and do not use Google account information for advertising. You can revoke access through your Google account settings; this does not itself delete your Lenskit account.

Content and correspondence

We store saved optical prescriptions, names, descriptions, settings, visibility choices, thumbnails, and personal lens-library entries. If you answer the optional project question, we store your category and any description. If you contact us, we receive your correspondence and use it to respond.

How we use information

We use information to provide authentication, saving, analysis, sharing, and other application features; send necessary service emails; prevent abuse; maintain reliability; and respond to requests. Optional research responses help us understand what to build. We do not sell personal information.

Visibility and sharing

Private systems are available through the application only to their owner. Anyone with a link can view an unlisted system. Public systems are discoverable in the gallery. Shared views may display the owner’s username. Viewers may obtain independent copies or exports; later making your original private or deleting it does not remove copies already obtained. Personal lens-library entries and project responses are not published with shared systems. Authorized operators may access stored information when necessary for service operation, support, or investigation of faults and abuse.

Optional analytics

LensKit uses limited usage events and client error reports to understand which features help people and where the app fails. Reports go to PostHog EU Cloud and include page categories, account setup completion, successful saves, analysis completion, and selected feature actions.

Reports use a random browser identifier rather than your account identity. We exclude optical prescriptions, system names and links, usernames, email addresses, sign-in tokens, free-text answers, and original error messages. Error reports can include application code locations. Session recordings, automatic click tracking, heatmaps, and console log collection are disabled.

Analytics is on by default where prior permission is not required. In regions requiring permission, or if we cannot determine your region, it stays off until you allow it. Cloudflare estimates your region from your IP address to select the applicable default. PostHog stores a random browser identifier in browser storage and cookies to connect usage within this browser. You can turn analytics off here or in Settings at any time; this stops future collection and clears PostHog tracking storage. Your choice is saved in this browser and overrides regional defaults. Turning collection off does not delete reports already sent; contact us about deleting your data. LensKit works with analytics off.

Answers to the optional post-setup question stay privately in LensKit’s database and are not sent to PostHog. They help the LensKit team decide what to build.

Cookies and browser storage

We use cookies and browser storage for authentication, security, preferences, and recovery of unsaved work. When analytics is enabled, PostHog also stores an identifier to connect events within your browser. Choices are specific to each browser. Recovery drafts may remain on your device; server-side deletion cannot erase files or storage on your devices.

Service providers

Cloudflare hosts Lenskit, stores application data and thumbnails, and provides Turnstile abuse prevention. Google authenticates users who choose Google sign-in. Brevo receives recipient addresses and email contents to deliver service emails. PostHog EU Cloud processes optional usage analytics and error reports. These providers process information needed to perform their services, including technical request information. They may process information outside your country. Use of PostHog EU Cloud does not mean all Lenskit information is stored exclusively in the EU.

Other disclosures

We may disclose information where required by law or necessary to investigate abuse, protect users and the service, or defend legal rights. We use service providers to operate Lenskit, rather than selling your information to advertisers.

Retention and deletion

We retain information while needed to provide the service and for the purposes described here. Temporary authentication and security records are subject to expiry and cleanup. Request account or information deletion at support@lenskit.app. We may need to verify your identity. We will respond and carry out applicable requests without undue delay and within deadlines required by applicable law. Account deletion covers associated information under our control, including saved content, library entries, research responses, and thumbnails. Deleting a system in the application removes access but may retain database records; contact us to request permanent erasure.

Backups and deletion limits

Earlier copies may remain in provider-managed backups or recovery history until normal retention expires. They are not used for ordinary operations, and completed deletion requests will be reapplied if a backup is restored. Limited information may be retained where necessary for legal obligations, disputes, or abuse prevention, with use restricted to those purposes. We cannot erase independent copies or exports held by others or storage on your devices. Analytics reports use a browser identifier rather than account identity; we may need that identifier to locate reports for deletion. Turning analytics off stops future collection but does not automatically delete earlier reports.

Your choices and rights

You can choose your sign-in methods, system visibility, whether to answer optional research questions, and whether to allow analytics. Contact support@lenskit.app to request access, correction, or deletion, or raise a privacy concern. Additional rights, including rights to object, restrict processing, or complain to a competent authority, may apply depending on your location and applicable law.

Security

We use secure connections, authentication, access controls, and other safeguards. No service can guarantee absolute security. Protect your sign-in methods and avoid sharing account access.

Children

Lenskit is intended for optical-design work and learning and is not directed at children under 13. Contact us if you believe a child under 13 has provided personal information so we can investigate and take appropriate action.

Policy changes

Updates will appear here with a revised effective date. We will provide appropriate notice of material changes and obtain additional consent where required, including before using Google user data for a new purpose.