How Does Starknet (STRK) Work? A Complete Breakdown of the ZK Rollup Transaction Flow

As the Ethereum ecosystem continues to expand, on-chain transaction volume and smart contract complexity keep increasing. The mainnet has long faced issues such as high gas costs, slow transaction confirmation, and limited throughput. Against this backdrop, Layer2 scaling solutions have gradually become an important direction for the Ethereum ecosystem, and Starknet is one of the most representative ZK Rollup networks among them.

At the same time, Starknet is not simply a “faster Layer2.” Its underlying design also combines STARK Proofs, the SHARP shared proving system, native Account Abstraction, and the Cairo programming language, making it one of the key infrastructure projects in Ethereum’s ZK scaling path.

Source: starknet.io

The Relationship Between Starknet (STRK) and Ethereum Layer2

Starknet is essentially an Ethereum Layer2 network. Its main purpose is to help Ethereum improve scalability.

Ethereum has a large smart contract ecosystem and strong decentralized security, but the mainnet itself has performance limits. When the number of on-chain users grows quickly, gas fees often rise noticeably, and transaction confirmation may slow down. During peak periods for DeFi, NFTs, and blockchain games, mainnet congestion becomes even more apparent.

For this reason, Layer2 has become an important direction for Ethereum scaling. The core idea of Layer2 is to execute a large number of transactions outside the main chain, then synchronize the final results back to Ethereum, reducing the computational pressure on the mainnet.

Starknet follows the ZK Rollup, or zero knowledge rollup, approach. In simple terms, Starknet processes transactions in batches on Layer2 and generates a mathematical proof showing that all those transactions are valid. The Ethereum mainnet does not need to re execute every transaction. It only needs to verify the proof to confirm that the state is correct.

This structure means Ethereum still provides final security, while Starknet improves execution efficiency. Starknet is therefore more like an execution scaling layer for Ethereum than an independent blockchain.

At the same time, compared with some sidechain solutions, ZK Rollup does not rely on an independent security system. Instead, it directly inherits Ethereum’s security. This is one of the major reasons Starknet has attracted long term attention.

How a Starknet Transaction Begins

On Starknet, the user interaction flow differs somewhat from that of traditional blockchains.

When users interact with a DApp through a wallet, they are essentially sending a transaction request to the Starknet network. Unlike Ethereum, Starknet accounts are smart contract accounts rather than traditional EOA, or Externally Owned Account, structures.

This means user accounts can support more flexible verification logic. For example:

• Multisig verification

• Social recovery

• Passkey login

• Session Key

• Custom signature rules

As a result, Starknet’s account structure natively supports Account Abstraction.

After a user initiates a transaction, the transaction content usually includes:

• The smart contract being called

• The function selector

• Parameter data

• Gas settings

• Signature information

The transaction is then sent to Starknet’s Sequencer node.

The Sequencer first orders, verifies, and executes the transaction, then temporarily updates the Layer2 state. At the same time, many user transactions are packaged into the same Batch, waiting for a zero knowledge proof to be generated later.

This structure allows Starknet to process a large number of transactions at once, rather than settling each one individually as the Ethereum mainnet does.

The Role of the Sequencer in Starknet

The Sequencer is one of the core components of the Starknet network.

Simply put, the Sequencer acts like the “transaction coordination center” of the Layer2 network. It is responsible for receiving user transactions, ordering transaction execution, generating blocks, and updating the Layer2 state.

After a large number of transactions enter the network, the Sequencer first places them into a Mempool, then orders them according to specific rules. Next, the Sequencer executes these transactions and calculates the new Layer2 state result.

During this process, users can usually see transaction execution results quickly, so the interaction experience on Starknet is noticeably faster than on the Ethereum mainnet.

However, it is important to note that although the transaction has already been executed on Layer2 at this point, it has not yet completed final settlement on Ethereum. Starknet still needs to generate a STARK Proof and submit it to Ethereum for verification.

At the same time, the Sequencer is also responsible for:

• Block construction

• State updates

• Batch transaction compression

• Data availability processing

• Network synchronization

In essence, the Sequencer serves as Starknet’s execution layer.

In the future, as Starknet advances its decentralization roadmap, the Sequencer structure may gradually evolve from a single sequencer into a more distributed network structure, further improving Layer2 decentralization.

How STARK Proofs Are Generated

STARK Proof is one of Starknet’s most important underlying technologies.

In Starknet, after a large number of transactions have been executed, the system does not send all transaction details directly to Ethereum. If Ethereum had to re execute every transaction, Layer2 would lose its scaling value.

Instead, Starknet uses zero knowledge proof technology to generate a mathematical proof showing that “the transactions were executed correctly.”

This process mainly relies on Cairo and the STARK, or Scalable Transparent ARgument of Knowledge, proof system.

First, transactions are executed in the Cairo virtual machine environment. The system then records the state changes throughout the execution process and generates the corresponding computational Trace.

Next, the Prover uses this execution data to generate a STARK Proof, proving that:

• All transaction execution followed the rules

• The state transition is valid

• No assets were forged

• No state was modified illegally

After that, the Ethereum mainnet only needs to verify this proof, rather than re execute the full transactions.

Compared with the “trust by default plus challenge period” structure of Optimistic Rollup, ZK Rollup follows a “prove first, then confirm” model.

As a result, Starknet does not require a long withdrawal waiting period and can achieve final confirmation more quickly.

At the same time, STARK Proofs also offer:

• High security

• Potential resistance to quantum computing

• No need for a Trusted Setup

• Stronger scalability

This is one of the key reasons Starknet chose the STARK path.

How Starknet Submits Transaction Results to Ethereum

After a STARK Proof is generated, Starknet submits the proof result to the Ethereum mainnet.

This process is mainly completed through SHARP, or the Shared Prover system.

SHARP can be understood as StarkWare’s shared proof aggregation system. It can aggregate proofs from multiple Cairo programs, multiple blocks, and even multiple applications, lowering the overall proving cost.

In simple terms, SHARP will:

• Aggregate execution results from multiple blocks

• Generate recursive proofs in a unified way

• Compress verification data

• Send the final proof to Ethereum

Because Ethereum only needs to verify one aggregated proof, a large number of transactions can share the same mainnet verification cost.

At the same time, Starknet also synchronizes the compressed State Diff to Ethereum to ensure Data Availability.

This means that even if Layer2 itself encounters problems, the network state can still be recovered through Ethereum data.

Therefore, in the Starknet architecture, Ethereum serves as the:

• Final security layer

• Proof verification layer

• Data availability layer

• Asset settlement layer

Starknet, meanwhile, is responsible for:

• High frequency transaction execution

• State computation

• Throughput scaling

This structure is the core reason ZK Rollup can balance security and scalability.

STRK’s Role in Network Operations

STRK is the native token of the Starknet network.

Its most basic function is paying network gas fees. When users execute transactions, call smart contracts, or deploy applications on Starknet, they need to pay STRK as the cost of network resources.

At the same time, STRK also supports the network’s economic incentive functions.

As Starknet continues decentralizing, STRK is expected to participate in:

• Sequencer incentives

• Network staking

• Consensus security

• Block ordering mechanisms

• Governance voting

For this reason, STRK is not merely a regular transaction token. It is more like a foundational economic asset within the Layer2 network.

In addition, STRK will also influence the network governance structure. As protocol upgrades, parameter changes, and ecosystem expansion move forward, STRK holders may participate in on-chain governance decisions.

This structure means STRK connects:

• Network operations

• Layer2 security

• Protocol governance

• Ecosystem incentives

• Resource consumption

Therefore, STRK’s long term role is not only to pay transaction fees, but also to participate in the entire Starknet network economy.

Advantages and Potential Limitations of Starknet’s ZK Rollup Mechanism

Starknet’s biggest advantage lies in its ZK Rollup architecture, which can balance scalability with Ethereum security.

Compared with executing transactions directly on the mainnet, Starknet can significantly reduce gas costs and increase transaction throughput. At the same time, because it uses STARK Proofs, transaction confirmation does not need to wait through a long challenge period as it does with Optimistic Rollup.

Starknet also has:

• Native Account Abstraction

• Cairo’s provable computation structure

• SHARP aggregated proofs

• Highly modular scalability

These designs make Starknet better suited to complex on-chain applications and future large scale Web3 interaction scenarios.

However, Starknet also has certain limitations.

First, Cairo differs significantly from Solidity, so the development threshold is relatively high. Many Ethereum developers need to learn a new development system.

Second, ZK Proof generation itself remains a highly complex computational process, so proof generation efficiency and hardware requirements are still long term areas of optimization for the industry.

In addition, today’s Layer2 ecosystem still faces liquidity fragmentation. Assets and users may be dispersed across different Rollups, which is another issue the broader Ethereum Layer2 ecosystem is working to solve.

Therefore, Starknet is more like a long term scaling path than a short term performance optimization tool.

Conclusion

Starknet is an Ethereum Layer2 network built on a ZK Rollup architecture. Its core goal is to improve on-chain execution efficiency and scalability while inheriting Ethereum’s security. Through STARK Proofs, SHARP aggregated proofs, and the Cairo execution environment, Starknet can compress large numbers of transactions and submit them to Ethereum for verification, reducing gas costs and improving throughput.

At the same time, Starknet is not just an ordinary Layer2 network. Its native Account Abstraction, provable computation system, and future decentralized Sequencer path also make it one of the key infrastructure projects in the ZK Rollup sector. As the Layer2 ecosystem continues to develop, Starknet is gradually expanding into more complex Web3 application scenarios.

FAQs

Is Starknet a Public Blockchain or Layer2?

Starknet is an Ethereum Layer2 network. It runs on ZK Rollup technology and relies on Ethereum for final security.

What Is STARK Proof?

STARK Proof is a zero knowledge proof technology used to prove that transaction execution results are correct without re executing all computations.

Why Does Starknet Use Cairo?

Because Cairo is a language specifically designed for provable computation, making it better suited to generating STARK Proofs.

What Does the Sequencer Do in Starknet?

The Sequencer is responsible for receiving transactions, ordering execution, generating blocks, and updating the Layer2 state.

What Is SHARP?

SHARP is StarkWare’s shared proof aggregation system, used to aggregate multiple proofs and reduce Ethereum verification costs.

What Is STRK Used For?

STRK is used to pay gas, participate in governance, support future staking, and maintain the network’s economic incentive structure.