A Classy Nostr Signer.
Sidecar is a Nostr signing extension that lives in your browser's side panel. It holds your keys locally — encrypted behind a PIN — so you can sign in and sign events across Nostr clients without pasting your nsec anywhere. It also has a built-in Lightning wallet (Nostr Wallet Connect) and a composer for posting notes directly from the panel.
Multiple accounts
Store as many nsecs as you like, switch the active one in a click, with a live preview on import.
PIN-protected
Every private key is encrypted at rest (PBKDF2 → AES-GCM). Nothing is stored in plaintext.
Lightning wallet (NWC)
Connect any Nostr Wallet Connect wallet. Send, receive, and pay invoices from any page. Sidecar never holds your funds.
Per-site permissions
Approve or reject each site, with a prompt that previews exactly what you're signing.
Profile & backups
Encrypt your profile, follows, and mute list to your own relays, or export a signed JSON bundle. There's no recovery if you lose your nsec, so back it up.
Note composer
Post notes right from the panel, with @mention autocomplete, event embeds, and media uploads to your own Blossom server.
“Best Nostr Extension ever! Every Nostr app should take notes on this onboarding flow. This makes me want to use Nostr.”
“Best UX for a browser key signer so far. […] I’m thinking about replacing Alby with Sidecar in NoorNote’s onboarding wizard because Sidecar is better for beginners right now.”
“I think Sidecar is the best full-fledged Nostr signer/wallet (browser extension) I’ve used so far! It covers all my needs […] If you need a Nostr signer that’s a browser extension, I highly recommend Sidecar.”
“Just installed it. Work of art.”
