# Aztec vs Starknet

> Starknet executes general-purpose contracts publicly; its STRK20 privacy pool gives a designated company access to viewing keys. Aztec lets applications define private and public logic without a network-wide viewing key.

Canonical: https://aztec.network/compare/starknet  
Type: Comparison  
Reviewed: 3 November 2026  
Publisher: Aztec Foundation

## Side by side

| | Starknet | Aztec |
| --- | --- | --- |
| Is the network unstoppable? | **Permissioned sequencing.** StarkWare runs all of Starknet's sequencers, so the company can halt the network, and has: on 5 January 2026 it paused block production for more than four hours and dropped 18 minutes of activity. L2BEAT lists permissioned sequencing and Stage 1 maturity, with an emergency upgrade path that has no exit window. | **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. |
| Is there a privacy backdoor? | **Audit key held by a company.** STRK20 viewing keys are encrypted to a master key in trusted enclaves, with multisig backups: a designated party can read shielded activity on request. | **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. |
| Do they have private smart contracts? | **Public contracts, private pool.** Cairo contracts execute publicly. STRK20 adds a privacy pool with its own disclosure model, not private contract logic. | **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. |
| Who can build and participate? | **Permissionless to use.** Contract deployment is open; sequencing remains permissioned. | **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 approach | A compliance layer built into STRK20: viewing keys are escrowed with an audit-key operator, which supports scoped disclosure for lawful requests. | 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 Starknet does well

General-purpose Cairo contracts and STARK-based scaling on Ethereum, with STRK20 supporting scoped disclosure for lawful requests.

**The difference.** For STRK20, disclosure runs through a designated audit-key operator and there are no smart contracts with private logic. On Aztec, the application defines disclosure without a protocol-wide audit key and the platform supports smart contracts with private logic.

## Sources

- [L2BEAT: Starknet](https://l2beat.com/scaling/projects/starknet)
- [Starknet: the compliance layer for STRK20](https://www.starknet.io/blog/compliance-layer-onchain-privacy-strk20/)
- [Starknet: 2025 year in review](https://www.starknet.io/blog/starknet-2025-year-in-review/)
- [Starknet: incident report, 5 January 2026](https://www.starknet.io/blog/starknet-incident-report-january-5-2026/)
- [Aztec: private and public state](https://docs.aztec.network/developers/docs/foundational-topics/state_management)
- [Aztec: privacy considerations](https://docs.aztec.network/developers/docs/resources/considerations/privacy_considerations)
- [Aztec: governance voting](https://docs.aztec.network/participate/token/voting)
- [L2BEAT: Aztec Network](https://l2beat.com/scaling/projects/aztecnetwork)

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Markdown representation of https://aztec.network/compare/starknet. Published by Aztec Foundation.