Base vs Arbitrum: What does each chain inherit from Ethereum and what does it run independently?

Both chains borrow two things from Ethereum: a public place to store transaction data and an arbitrator to resolve disputes when someone claims the result is wrong.

All other aspects-who is responsible for sequencing transactions, who can challenge those transactions, and who holds the keys to upgrade the system-are determined independently by each chain's own operator and governance structure, and Base and Arbitrum have different answers on these questions.

The division of labor done for each optimistic summary

Based on Arbitrum's own documentation, optimistic summaries separate the two tasks Ethereum typically handles simultaneously: running transactions and updating status (execution), and agreeing on specification results and keeping underlying data retrievable (settlement and data availability). Arbitrum puts the first task under the chain and hands the second task over to Ethereum. The official Ethereum document's explanation of optimistic aggregation describes the same division of labor: aggregation performs transactions on its own virtual machine, and then publishes the transaction data to Ethereum as calldata or blobs, so that anyone can rebuild the status of the aggregation and check it. The document states that this design can provide "up to 10 to 100 times scalability improvements" compared to running all operations directly on the Ethereum base layer.

Because data exists on Ethereum, challengers do not need to trust aggregation operators. If the published results appear problematic, challengers can build fraud proof from these public data and force Ethereum to arbitrate. It is this arbitration role, not execution itself, that is the true meaning of "inheriting Ethereum security."

Part of the Arbitrum itself running

According to the Arbitrum documentation, the Arbitrum One runs on Nitro, a modified fork of Geth, Ethereum's most widely used client software. According to related reports, Nitro Stack is maintained by Offchain Labs. As of April 2026, Arbitrum One is operated by the Arbitrum Foundation and has a security committee for token governance. Governance runs through the Arbitrum DAO: $ARB token holders and their representatives vote on the proposal, while the Arbitrum DAO glossary states that the Arbitrum One has two chain owners with the right to upgrade core protocol contracts-the Arbitrum DAO and the Security Committee.

The dispute mechanism is called BoLD. According to Arbitrum's documentation, when two verifiers disagree on the outcome of a transaction, each party gradually bisects its claimed commitment history until a single order in dispute is isolated, and Ethereum then only rules on the order without having to re-execute the entire batch. Arbitrum's documentation states that only one honest verifier is needed to keep the chain safe because that verifier can catch multiple malicious actors. BoLD reportedly enabled license-free verification at the end of 2025, which means anyone can now run a validator and submit a fraud certificate without having to join the license set. As of April 2026, Arbitrum is the only L2 that has been classified as Stage 1 by L2BEAT based on this. It is also reported that as of April 2026, the Arbitrum Security Committee has 12 members, distributed in multiple companies.

Part of Base's own running

According to relevant reports, Base runs on OP Stack, an open source aggregation framework that is also used by Optimism's OP mainnet and incubated by Coinbase. The report pointed out that Base does not have native governance tokens or utility tokens, uses ETH as fuel, and Coinbase has said it has no plans to issue tokens. Another report said that Base will be launched on its main network in August 2023. As of March 2026, it handles approximately 8.93 million transactions per day, but this figure fluctuates greatly. The same report also pointed out that as of February 2026, Base plans to move from OP Stack to its own unified, Base-operated stack, which will change what Base will obtain from Optimism sharing tools in the future.

According to multiple reports, Coinbase controls Base's sorter. According to reports, as of April 2026, Base shares sorter fee revenue with Optimism Collective under the Hyperchain Agreement, and Base's security committee includes Coinbase and external members.

Contradictory evidence for the decentralization stage

In terms of the decentralization stage, this set of evidence is directly contradictory. A report stated that Base became a Phase 1 aggregation in April 2025 and has deployed a functional attestation system and an independent security committee that can override erroneous state roots. Another report released on July 20, 2026 and describing the situation as of April 2026 pointed out that Base is in Stage 0 of L2BEAT, and the failure certificate was deployed to the Base main network in October 2024, but the security committee's multi-signature still holds upgrade rights. Both claims come from their respective sources, not from L2BEAT's own page, and the two have different opinions on the stage Base will be in about a year later. Therefore, this article is presented side by side and will not be ruled.

The only delay imposed by Ethereum: withdrawals

Within both chains, ordinary transactions do not have to wait for Ethereum. Delays specifically arise when funds are moved back to Ethereum. Arbitrum's documentation states that it usually takes 6.4 days to withdraw money from Arbitrum to Ethereum, while there are no such delays when depositing Arbitrum from Ethereum, and third-party fast bridges can skip the wait by paying a fee. Another report describing the situation of Base and Arbitrum as of April 2026 noted that both chains allowed a seven-day challenge window. These two numbers-6.4 days in Arbitrum's own documentation and 7 days from another source-are not the same, and this article lists both without making trade-offs.

The official Ethereum document explains why there is a wait: After a batch is released, there is a window period where anyone can calculate fraud certificates for the batch; if the batch is not challenged, it is considered finalized on Ethereum. Another report added that on Base and Arbitrum, if the sorter refuses to include a transaction, users can force the transaction directly through Ethereum, although the report noted that this path is not practical in practical use given the multi-day delay involved.

Common misunderstandings

Marketing language says aggregation "inherits the security of Ethereum", which can easily be understood as the aggregation is as decentralized as Ethereum itself. Available evidence does not support this interpretation. Ethereum ensures that underlying transaction data remains available and that once disputes are raised, they will be resolved by Ethereum rather than the operator of the chain. It does not say who can generate blocks in the first place, who can pause the sorter, or who holds the key to change the contract. On these issues, Arbitrum runs a token-governed DAO, has a security committee, and reportedly has a permission-free collection of validators as of April 2026; while Base runs on a sorter operated by Coinbase, has no governance tokens, and its security committee upgrade rights are still described as centralized at the same point in time.

Information not provided in this article

This article cannot tell readers which chain currently has higher total lockdown value, lower fees, or more daily users. The data cited-Base and Arbitrum's L2BEAT reports TVLs of $4.6 billion and $1.3 billion respectively as of April 2026, and Base's daily transactions of approximately 8.93 million as of March 2026-are snapshots at specific points in time obtained from second-hand sources, not real-time data from L2BEAT or Chain Browser, and both indicators change weekly.

This article does not address the issue of whether Base was in L2BEAT Stage 1 (according to one source) in April 2025 or Stage 0 (according to another source) as of April 2026. Both are dated above and attributed to the source where they were reported, as none of this evidence collection is L2BEAT's own pages.

The claim that Coinbase applied the address restrictions listed in OFAC to Base's sorters came from a report that claimed this was the content of Coinbase's public statement; this evidence set does not directly contain Coinbase's statement, so it is attributed to the report rather than Coinbase as a primary source.

This article does not cover other Ethereum Layer-2 networks, does not compare any chain to zero-knowledge aggregation, nor does it claim which chain is better suited to building applications or holding assets-this requires readers to make their own judgments based on the different trade-offs involved in a particular use case.