A client-side-proving rollup, spun out of Polygon
Aztec vs
Miden
Miden opened an invite-only partner mainnet in October 2026: Miden operates the validators, which hold threshold keys to encrypted transaction data, and Guardian co-signers see the state of the accounts they back. Aztec runs a permissionless network where no operator or co-signer can read a private transaction.
| Questions | Miden | Aztec |
|---|---|---|
Invite-only, Miden-run The partner mainnet is invite-only. Miden operates the validator set, and the documented operator roles cover sequencing, proving, data availability, and L1 submission. | No one can stop it Permissionless sequencers and provers run the network. Upgrades follow public governance rules with a timelock. L2BEAT assesses the rollup at Stage 2. | |
Validators hold the keys Encrypted transaction data is shared with the validators, and a threshold of them can decrypt it. The Guardian behind a Bread account can see that account's state. | No backdoor Private functions execute on the user's device and the network verifies a proof. There is no network-wide decryption key, no validator that re-executes private inputs, and no co-signer. Public calls and their inputs are visible by design. | |
Private accounts and notes Smart contracts in Rust with private accounts and notes, executed and proven on the user's device. A private note puts only its hash onchain and its contents stay off-chain; encrypted notes, which would put the contents onchain encrypted for the recipient, are listed as a planned feature. | Private + public contracts Noir contracts combine private state and functions with public ones, and anyone can deploy them. Contracts compose on Aztec and reach Ethereum through L1/L2 messaging. | |
Permissionless to use The partner mainnet is open to partners and to Bread users with an invitation code, under regional restrictions. Operating a validator is not open. | Permissionless to use, build, and operate Anyone can deploy contracts or participate as a sequencer or prover under the published protocol, staking, and hardware requirements. | |
Compliance runs through Miden's operators. The Guardian, the "entry point to Miden", exists to "manage state, co-sign transactions, and enforce compliance": every send, receive, and swap from a Bread account takes its signature, its operator can see the account's state, it denies transfers to OFAC-sanctioned addresses, and it may charge a "review fee" on transactions over $10,000. Miden launched private between users "but not against the operators", and its essay on practical privacy proposes conditions on large transfers: delays, proof of funds, or viewing keys a subset of validators could use to decrypt them. A user can instead choose an account that shares nothing with an operator, and has no recovery. | Selective disclosure at the application and user level. An application decides which facts it proves or publishes, and a user can share their own viewing keys with whoever they choose. No protocol-wide audit key, screening gate, or operator sits in the path of a transaction. |
What Miden does well.
Client-side proofs, Rust tooling, and a polished wallet: Bread with passkeys, spending limits, Guardian recovery, and private multisig with mixed Falcon and ECDSA keys. Private accounts and notes put only a commitment onchain and their users keep the contents off-chain, so a future break of encryption exposes nothing from the chain itself.
The difference. Both designs prove privately on the user's device. The difference is who else is in the path: on Miden, encrypted transaction data goes to a validator group that can decrypt it together, a Guardian sees the state of every account it backs, and Miden runs the validators. On Aztec, no one sees that data, and no one can stop the network: permissionless sequencers and provers run it.
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