Sigma Auth vs Privy
Privy gives EVM applications embedded wallets and social login. Sigma Auth gives users a Bitcoin anchored identity whose key never leaves their device. Strip away the feature lists and the comparison is one question: who holds the key your users sign with.
Choose Privy if
- You are building on EVM and want users onboarded without a wallet install
- Social login is the front door and the wallet should appear quietly behind it
- You want gas sponsorship and funding flows already wired up
- Managed key infrastructure is an acceptable dependency for your product
Choose Sigma Auth if
- Users should hold their own keys, with no share retained by a provider
- Identity should be anchored on Bitcoin and portable through a backup the user controls
- Access should be gated on what a user actually holds
- Self hosting under MIT matters to your risk model
The difference in one picture
Everything else on this page follows from these two diagrams.
Feature comparison
| Privy | Sigma Auth | |
|---|---|---|
| Chain focus | EVM chains including Ethereum, Base, and Polygon | Attestation hashes anchored on Bitcoin SV. The identity itself can be generated from a key already held on Ethereum, Bitcoin, Bitcoin Cash, Bitcoin SV, Litecoin, Avalanche, ICP, and Solana |
| Wallet model | Embedded wallets with server side key sharding | Non custodial. The key stays on the user device |
| Key custody | Privy holds a key share | Sigma never receives the private key |
| Primary authentication | Email, social OAuth, passkeys | Bitcoin signatures, plus OAuth providers |
| Identity model | Email based accounts | BAP cryptographic identity, anchored on chain |
| Recovery | Provider assisted recovery | Encrypted backup file, portable across devices |
| Access control | Token gating through smart contracts | NFT ownership, token balance, BAP allowlist |
| License | Proprietary | MIT |
| Self hosted | No | Yes |
| Pricing model | Free tier, then paid tiers | Free self hosted. The hosted service currently has no paywall |
| Onboarding friction | Very low. No wallet install required | Low with an existing wallet. Otherwise a key is generated on first use |
Verified on 21 August 2026.
Where Privy is strong
Onboarding without a wallet install
The wallet install step is the single largest drop off in most crypto products. Removing it is a real result, and embedded wallets remove it completely.
Broad EVM coverage
If your contracts live on Ethereum, Base, or another EVM chain, Privy meets your application where it already is rather than asking it to move.
Funding and sponsorship are wired
Paymaster style gas sponsorship and funding paths ship as part of the product, which removes a meaningful amount of integration work.
Social login as the front door
Users who would never describe themselves as crypto users can sign in with an account they already have and end up with a wallet without thinking about it.
Where Sigma differs
Users hold their own keys
No key share is retained by Sigma. A user's ability to act cannot be suspended, and Sigma cannot sign on their behalf even if compelled to.
The key you already hold is the one you use
The attestation hashes are anchored on BSV. The key that generates the identity can be one a user already holds on Ethereum, Bitcoin, Bitcoin Cash, Bitcoin SV, Litecoin, Avalanche, ICP, or Solana. EVM chains and Bitcoin share the secp256k1 curve, so an Ethereum wallet also yields a BSV address the user can recover independently. See the EVM path.
Recovery is a file, not a request
An encrypted backup moves an identity between devices. Restoring is something the user does, not something they ask a provider to approve.
Access follows ownership
Gate on NFT ownership, token balance, or a BAP allowlist, verified against the chain rather than against a subscription table.
Moving from Privy
Four steps. The order matters more than the speed, because the custody model changes underneath your users rather than beside them.
- 01
Inventory the user base and the wallet types
Split your users into those who connected an external wallet and those who were given an embedded one. The two groups migrate differently, and the ratio decides how much of the work is communication rather than code. What Privy can export, and in what shape, is the first thing to confirm in Privy's current docs.
- 02
Map embedded wallet users to self held keys
Users who connected their own wallet already hold a key, so they can sign into Sigma with it directly. Embedded wallet users hold nothing today, so plan an explicit step where a key is generated or imported on first sign in, followed by the encrypted backup. Whether existing embedded key material can leave the provider at all is a question to confirm in Privy's current docs rather than assume.
- 03
Run both providers in parallel behind Better Auth
Sigma ships as
@sigma-auth/better-auth-plugin, so a project already running Better Auth can mount Sigma alongside its existing provider rather than swapping one for the other on a single night. Users move as they sign in, and you keep a way back for as long as you need one. - 04
Cut over once the traffic has moved
When the remaining share of sign ins through the old provider is small enough to handle by hand, make Sigma the default and retire the parallel path. Keep the old read path available slightly longer than feels necessary, because the last few users are always the ones who took a long holiday.
Try the wallet path
Connect a wallet you already have, sign once, and see what a Sigma identity looks like before committing to anything. You can also review all the alternatives first.