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Does Arbitrum have a Mempool?


As blockchain technology continues to transform, scalability has been a focal point in achieving mainstream adoption. This has led to the birth of some unique Layer 2 scaling solutions that resolve these limitations and Arbitrum is one the prominent L2 solutions among them.

Unlike Layer 1 blockchains, which rely on a mempool (a holding area for pending transactions), Arbitrum has adopted a unique architecture that does not utilize a traditional mempool. Instead, it improves the scalability problems by processing transactions in batches and broadcasting them to Ethereum. Further, it uses optimistic roll-up technology to enhance the overall transaction throughput and efficiency.

This leaves us with the exciting question of how arbitrum processes transactions without a mempool. Let's explore it in more detail.

How Arbitrum Works?

Arbitrum utilizes a single sequencer model over mempool for transaction processing. Think of sequencer as a single program in the Arbitrum Ecosystem that keeps track of all the transactions and processes them seamlessly before sending them to the Ethereum chain.

The single sequencer model queues and processes the transactions in a first-come, first-serve manner. As soon as the sequencer receives a transaction it is added to the transaction queue awaiting processing. Importantly, this queue is not limitless, and transactions can timeout if not processed quickly, creating an urgency for rapid execution.

Further, all the transactions get bundled into different batches which improves the efficiency of processing them.

Soon after bundling, the Arbitrum sequencer starts processing them “off-chain” using the concept of “optimistic rollup”. Optimistic rollup is the technology where transactions are executed in a trustless manner assuming they are valid until someone proves otherwise. Arbitrum has achieved low transaction fees and computational overhead by processing transactions off-chain.

After processing transactions, the sequencer sends the batches to the Ethereum mainnet layer 1 chain, which ensures the immutability and security of the transaction history.

Advantages and Disadvantages of Single Sequencer Model

Unlike other decentralized transaction processing frameworks, the single sequencer model is quite an efficient and structured framework for processing transactions. A few of the key advantages and disadvantages are listed below.


  • With a single sequencer model, transaction processing becomes quite straightforward and streamlined, as there is one single node, it eliminates challenges like the use of high computational power and simplifies the overall transaction management process. This efficiency translates into lower overhead and faster transaction confirmation times for users.

  • By doing off-chain computation, it lowers the transaction cost and amount of gas required to process the transaction. This makes it quite affordable for developers and users to interact with decentralized applications, potentially driving wider adoption.

  • Centralized transaction processing using a sequencer maintains consistency in the order of transaction execution and reduces the risk of any transaction conflicts or errors such as double-spending. This enables the predictability and reliability of transaction processing.


  • One of the major concerns with a single sequencer model is a potential single point of failure. Since all the transactions are processed in one single entirety, the breakdown or disruption of the sequencer could impact the functionality of the full ecosystem resulting in downtime or loss of funds.

  • The sequencer holds complete authority and power over the network that could potentially censor or process certain transactions over others based on any biases or factors.

  • It has a low degree of decentralization, which deviates from the blockchain ethos. Having no decentralization introduces risk to potential network attacks and threats.

Distributed Sequencer Technology

To overcome the challenges of the single sequence model, various researchers and technologists have proposed a solution to decentralize transaction sequencing on L2 chains by developing distributed sequencer technology.

Distributed Sequencer Technology consists of a group of network validators (individuals, communities, or groups of operators) that come together to act as a single validator. This helps to address the drawbacks of a single sequencer model like a single point of failure.

In the DST framework, all the validators are responsible for validating the same set of transactions, reducing the overall risk of manipulation or bias. Additionally, having multiple validators improves the security and reliability of the network by preventing any malicious actor from compromising the network.

Under the hood, it uses the Proof of Authority consensus mechanism to incentivize validators for their honest and fair act and ensure that all the validators are from known and trusted entities to prevent anyone from getting control over the network. Using this mechanism, if any validator is not performing fairly then they need to face some consequences like no rewards or paying penalty.

Overall, DST has the great potential to reduce different geographic, financial, and technical barriers. It can play a great role in decentralizing L2 solutions by replacing a single point of failure with multiple nodes spread across the globe working together to validate and process transactions.

Examples and Use Cases

SafeStake, a leading blockchain technology company is leveraging DST to transform Ethereum staking. At the core level, it utilizes distributed validator technology to enhance the overall security and reliability of the Ethereum validator. Further, it has also achieved a way to maximize the staking rewards and minimize the penalties of validators using DST.

Similarly, there are a lot of other aspects in various industries where one can leverage Arbitrum and Distributed Sequencer Technology. This includes use cases in gaming and decentralized finance (DeFi), among others.

For example, a decentralized exchange (DEX) could use DST to reduce Ethereum gas fees associated with order execution and settlement. This could lead to more cost-effective trades and faster order completion, attracting users seeking alternatives to high-cost platforms.


In a nutshell, Arbitrum is an innovative solution to solve the scalability problem in the web3 ecosystem by leveraging a single sequencer model.

While this model offers advantages in terms of transaction fees and throughput, it also poses some flaws like centralization.

However, with ongoing research and technical advances, including DST ( Distributed validator Technology), these risks could mitigate and enhance the reliance and decentralization of the blockchain ecosystem.

As the Layer 2 scaling solutions continue to transform, Arbitrum remains at the forefront of innovation and improvisation constantly.

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This article has been written by guest writer Vishal Saha

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