Sidecar: A classy Nostr NIP-07 signer that lives in your browser sidebar

Sidecar is a NIP-07 signing companion for Chrome and Firefox. It sits in the browser’s side panel (sidebar), so it stays open beside the client you’re using rather than closing every time you click away.

I built it for running several Nostr profiles at once. Each site binds to the account it first logged in with, so switching the active account in Sidecar doesn’t quietly change who an already-open tab is posting as. (This can be overridden in the Activity tab for users who prefer a faster, but riskier posting method.)

Because the panel is designed to remain open, it carries things a signer normally wouldn’t: a note composer, a notifications feed, and an NWC wallet for zaps, which can be encrypted and backed up to the user’s own relays for fast retrieval.

Available from Chrome Web Store, and as a signed direct download for Firefox: https://sidecar.top

GitHub: https://github.com/dmnyc/sidecar