Sigma Auth documentation
Sigma Auth combines Better Auth accounts and sessions with client-side Bitcoin identity signing. Start with the quickstart to add sign-in to an application, or account and security to use an existing identity.
Choose a guide
| Task | Documentation |
|---|---|
| Add sign-in to an app | Integration, Next.js, React, JavaScript |
| Register and manage an OAuth client | Client registration |
| Understand tokens and PKCE | Tokens, PKCE, OAuth API |
| Manage identities, sessions, passkeys, and linked accounts | Account guide |
| Restore an encrypted backup | Backup overview, social recovery |
| Connect wallets and check NFTs | Access control, wallet API |
| Read, edit, or publish a BAP profile | Profiles |
| Use a browser wallet to sign | Signing |
| Authorize a device or agent | Device flow, agents |
| Manage a team and delegated authority | Teams and delegations |
| Acquire and disclose identity certificates | Wallet credentials |
| Explore handles and messaging | Handles and messageboxes |
| Find machine-readable contracts | Discovery |
Domains and availability
sigmaidentity.com hosts product pages and these docs. auth.sigmaidentity.com hosts sign-in, accounts, and auth APIs. A relative API path in these docs uses the auth host unless a page explicitly says otherwise. Your application's own session lives on your application's origin.
Sigma uses Better Auth's OAuth 2.1 provider, with authorization codes and S256 PKCE. OAuth 2.1 is still an IETF draft; references to the published OAuth 2.0 RFCs and /oauth2/ endpoint names remain correct. The live discovery document describes deployed protocol capabilities. Sigma's Bitcoin client-authentication hook adds requirements beyond generic Better Auth examples.
A catalog entry or deployed route does not guarantee production activation. Certificates, seed creation, handles, and commercial features have separate availability controls, described in their guides. These docs were audited against the production source on September 5, 2026; no latency SLA, universal wallet compatibility, or planned billing entitlement is implied.
For help, use the contact page. Never send a private key, recovery phrase, backup password, session cookie, or token in a support report.