Privacy Policy

Last updated: March 19, 2026

Shelf ("we," "us," or "our") is a Chrome extension that helps online resellers crosslist items between marketplaces. This privacy policy explains what data we collect, how we use it, and your rights.

No marketplace passwords

Shelf does not store, transmit, or request your marketplace passwords. The extension detects your existing login sessions in Chrome — the same sessions your browser already maintains when you visit eBay, Poshmark, or Mercari. We never see or handle your login credentials.

Data stored locally

Your inventory data (item titles, descriptions, photos URLs, prices, and listing statuses) is stored locally in your browser using Chrome's chrome.storage.local API. This data stays on your device and is not sent to our servers unless you create an account and opt into cloud sync (a future feature).

Photos

Shelf stores photo URLs, not the photo files themselves. We reference the image URLs from your original marketplace listings. Photos are never uploaded to Shelf's servers.

Authentication

If you choose to create a Shelf account, authentication is handled by Supabase (a third-party auth provider). You can sign up with email and password or use Google OAuth. Shelf stores your authentication tokens locally in chrome.storage.local to keep you signed in. We store your email address and a unique user ID on our servers for account management.

Payment processing

Subscription payments are processed by Lemon Squeezy, a third-party payment processor. Shelf never sees, stores, or handles your credit card number, billing address, or other payment details. Lemon Squeezy notifies us via webhook when a subscription is created, updated, or cancelled — we only receive your user ID and subscription status.

Error tracking

We use Sentry for error tracking. When the extension encounters an error, Sentry captures the error message, stack trace, browser name and version, and extension version. Sentry does not capture personal data like your name, email, inventory, or marketplace activity.

Analytics

We collect minimal, anonymous usage analytics to understand how people use Shelf — for example, how many crosslists are performed and which marketplaces are most popular. These analytics do not include personal information or your inventory data.

What we do NOT do

Shelf does not sell your data to third parties. Shelf does not serve advertisements. Shelf does not track your browsing activity outside of the supported marketplace websites. Shelf does not share your inventory data with other users.

Data deletion

You can delete all locally stored data at any time by uninstalling the extension or clearing the extension's storage from Chrome settings. To delete your Shelf account and any server-side data, contact us at support@shelf-app.com and we'll process your request within 7 days.

Chrome extension permissions

storage — stores your inventory, settings, and authentication tokens locally on your device.

activeTab — reads listing data from the current marketplace page when you click the extension.

alarms — runs periodic sale detection checks every 15 minutes in the background.

notifications — shows browser notifications when items sell or are auto-delisted.

tabs — opens marketplace pages in background tabs for sale detection and delisting.

Host permissions (ebay.com, poshmark.com, mercari.com) — allows the extension to read listings, fill crosslisting forms, detect sales, and delist items on these specific websites.

Contact

Questions about this privacy policy? Reach us at support@shelf-app.com.