Sidecar is a Nostr signing extension that lives in a browser's side panel. It stores private keys locally, encrypted behind a PIN, allowing users to sign in and sign events across Nostr clients without exposing nsec keys by pasting them into websites.
It supports multiple accounts so that users can store as many nsecs as desired and switch the active one with a click, including a live preview on import. Every private key remains encrypted at rest using PBKDF2 and AES-GCM, with nothing stored in plaintext. A built-in Lightning wallet operates through Nostr Wallet Connect, letting users connect any compatible wallet to send, receive, and pay invoices from any page while Sidecar itself never holds funds.
Per-site permissions require approval or rejection for each site, accompanied by a prompt that shows exactly what is being signed. Profile and backup functions encrypt a user's profile, follows, and mute list to their own relays, or allow export of a signed JSON bundle. A note composer enables posting notes directly from the panel and includes at-mention autocomplete, event embeds, and media uploads to a user's own Blossom server.
Sidecar is delivered as a browser extension available for Chrome and Firefox. It functions as a NIP-07 compliant Nostr signer with an integrated Lightning wallet. The project provides releases on GitHub, including version 1.5.0 from July 21, 2026, offered as zip files for both browsers. No pricing information appears in its description.
A Classy Nostr Signer is a Productivity & Work product. Securely signing Nostr events and managing keys across clients without repeatedly pasting private keys or nsec strings. It is built as a consumer product for nostr users and crypto enthusiasts. The product is available for free. A Classy Nostr Signer is available on the web and embeddable surfaces.
A Classy Nostr Signer first shipped in 2026. Development happens publicly on GitHub with 266 commits in the last 90 days. Key capabilities include Multiple Accounts, PIN Protection, and Lightning Wallet.
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