Your work should stay under your control.

What Penombra stores

• Free notebook drafts are stored in your browser on your device.
• Documents you upload are stored privately with a pseudonymous device identifier so they can be returned only to the same browser.
• A one-way identifier and daily count are stored to enforce the free explanation allowance.
• When you create a Pro account, Penombra stores your email, plan status, synced notebooks, notes, and collaboration permissions.
• Stripe stores payment details. Penombra stores only the billing identifiers and subscription status needed to recognize Pro access.

When AI sees page content

Penombra does not use your notebook to train a Penombra model. When you request an explanation, cleanup, diagram, or generated image, the content needed to answer that request may be sent to the configured AI providers, currently Google Gemini and, for limited fallback requests, Anthropic. Do not submit information you are not authorized to share with those services.

Service providers

Penombra relies on Supabase for accounts and cloud data, Stripe for billing, Cloudflare for abuse protection and network services, Railway for application hosting, and the AI providers described above. Each provider processes data needed to perform its role.

Your controls

You can delete uploaded documents from the app, clear device-local drafts through your browser, download notebook backups from the editor, and download your signed-in cloud data from the account page. Pro billing can be canceled through the Stripe-hosted billing portal. During the private alpha, ask the Lens organization contact who invited you if you need the remaining account data deleted.

Retention and security

Device-local data remains until you clear it. Uploaded documents remain until you delete them, and account data remains while the account is active or as needed for security, billing, legal, and operational records. Penombra uses access controls, private storage, encrypted transport, and limited server credentials, but no online service can promise absolute security.

Age and changes

Penombra is not directed to children under 13. This notice may be updated as the alpha changes; the date above will change when it does.