Security & your data

How local-first design keeps sensitive lists private. Plain-language overview, not legal advice.

Your lists never leave your device

Listalyze processes your data in your browser. When you paste text or open a file, the sorting, cleaning, deduplication and regex work run locally using WebAssembly. The contents of your lists are not uploaded to a server — not to us, not to a third party. We cannot read them because we never receive them.

That matters when the list is sensitive: a customer email export, an internal user list, or anything you could not paste into a cloud tool without a compliance headache. With Listalyze there is nothing to upload, so there is no copy of your data sitting on someone else's server.

What your account stores

You can use the core tool with no account at all. If you sign in with ConfirmID, we store your email address and basic profile information to identify you, restore your saved work, and manage a Pro subscription. We do not store the contents of the lists you process. Autosaved sessions are kept locally on your device using the browser's Origin Private File System (OPFS), under your control.

Transport security

The website and app are served over HTTPS and hosted on Cloudflare, which provides TLS encryption and edge protection. Standard, operational server logs apply (see the Privacy Policy), but the payload of your lists is never part of a request because the processing happens on your machine.

What this means in practice

• No upload step, so no list to intercept in transit or leak at rest.
• Works offline once loaded — useful on locked-down or air-gapped machines.
• You stay in control: clear your browser storage and the local data is gone.

Want the details on what is and isn't stored? Read the Privacy Policy and the Cookie & storage notice.

Last updated: 2026-06-19