# What is Starknet? Cairo accounts and validity proofs on Ethereum

Starknet is an Ethereum validity rollup that proves execution with STARK-based proofs and publishes compressed state information to Ethereum. Its accounts are smart contracts with validation logic, rather than Ethereum-style externally owned accounts alone. Use Starknet-aware accounts, tooling and asset routes; an Ethereum address or contract workflow is not automatically portable unchanged.

Evidence: [Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md); [Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md)

Canonical: https://degreesofsatoshi.com/encyclopedia/starknet/
Published: 2026-10-02
Substantively modified: 2026-10-02
Independently verified by an automated reviewer: 2026-10-02T19:27:58.939Z
Data current through: 2026-10-02

AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied.

## Key facts

- **Proofs:** Starknet submits proofs supporting its execution results to Ethereum. ([Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md))
- **Data:** Its protocol publishes compressed state differences for reconstruction. ([Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md))
- **Accounts:** Starknet account contracts separate validation and execution logic. ([Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md))

## Execution is proved before Ethereum accepts the result

Transactions are ordered into blocks and the proving system produces evidence that the protocol’s execution program yields the claimed state. Ethereum-side verification checks that evidence instead of running each Starknet transaction as an Ethereum transaction.

The proof is one component of the system. Data availability, sequencing and account validation remain distinct parts of how a user’s transaction succeeds.

Evidence: [Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md)

## A smart account can use its own authorization rules

Suppose a Starknet account requires multiple approvals through its validation function. A transaction must satisfy that account’s rules before its requested calls execute. The account design determines the accepted authorization, rather than assuming one fixed Ethereum EOA signature rule.

This flexibility also means account implementation matters. A network’s support for smart accounts does not guarantee every wallet includes the same recovery or permission features.

Evidence: [Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md)

## Use the right account and contract environment

Starknet uses its own contract and account interfaces, with Cairo-based execution tooling described by the protocol. Ethereum applications cannot assume that copying an address and raw EVM transaction reproduces the same operation.

Check the intended network, token representation and supported bridge before sending. A validity proof does not verify that you selected the recipient or asset you meant to use.

Evidence: [Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md); [Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md)

## Questions

### Are all Starknet accounts simple Ethereum-style EOAs?

No. Starknet accounts are smart contracts whose validation and execution functions implement the account’s behavior.

Evidence: [Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md)

### Does a STARK proof make every application safe?

No. It proves the specified computation under the protocol’s rules. It does not establish that an application’s economic promises or user-selected destination are appropriate.

Evidence: [Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md)

## Claims and scope

### starknet-quick-answer

Starknet is an Ethereum validity rollup that proves execution with STARK-based proofs and publishes compressed state information to Ethereum. Its accounts are smart contracts with validation logic, rather than Ethereum-style externally owned accounts alone. Use Starknet-aware accounts, tooling and asset routes; an Ethereum address or contract workflow is not automatically portable unchanged.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### starknet-fact-proofs

Proofs: Starknet submits proofs supporting its execution results to Ethereum.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### starknet-fact-data

Data: Its protocol publishes compressed state differences for reconstruction.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### starknet-fact-accounts

Accounts: Starknet account contracts separate validation and execution logic.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

## Sources

- [Starknet architecture](https://docs.starknet.io/learn/protocol/intro.md) — Starknet. Cairo-based execution and STARK proof settlement on Ethereum. Locator: Architecture; execution; proving; settlement. Retrieved: 2026-10-02T18:55:28.216Z.
- [Starknet accounts](https://docs.starknet.io/learn/protocol/accounts.md) — Starknet. Native contract-account validation and execution differ from Ethereum EOAs. Locator: Account abstraction; validation. Retrieved: 2026-10-02T18:55:28.472Z.

## Revision history

- 2026-10-02: First publication after primary-source research and separate automated verification.

## Cite this entry

Degrees of Satoshi editorial project. “What is Starknet? Cairo accounts and validity proofs on Ethereum.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/starknet/