TL;DR: Fault proofs are now live on Base Mainnet, marking a key milestone on our path to decentralization. With this upgrade, anyone can now participate in securing Base, creating a more trusted and open economy for everyone.

Building towards decentralization

From the beginning of Base, we have championed the belief that creating an open, global onchain economy is only possible on a decentralized platform. This is why Base is:

• Built on Ethereum — the most secure and decentralized L1.

• Built on Optimism’s open-source OP Stack — an open-source public good that serves as the foundation for a Superchain of L2s that will share interoperability, security, and governance.

• Committed to the Law of Chains with Optimism, which includes a commitment to neutrality, a decentralized security model, ecosystem protections, and community governance principles.

• Upholding the Base Neutrality Principles, including user autonomy, unbiased transaction sequencing, discretion with non-public data, and unrestricted withdrawals.

We’re laser-focused on making continuous advancements towards full decentralization. This is why, today, we’re taking the next important step in decentralizing the network: fault proofs are now live on Base Mainnet.

What fault proofs mean for Base

Vitalik’s decentralization framework lays out a path for Layer-2 rollups on Ethereum, like Base, to progressively and safely decentralize. Fault proofs are an essential component of going from Stage 0, in which a rollup has “full training wheels,” to Stage 1, which has “limited training wheels”.

This year, the Base core team collaborated closely with Optimism to bring the OP Stack Fault Proof System to Base. This enables a decentralized approach to proposing and validating L2 state, and paves the way towards more community participation.

Fault proofs have two important capabilities to improve decentralization:

• Permissionless proposals: Fault proofs help validate the state of Base in a decentralized way, allowing any participant to propose claims about the overall state of the chain, and the legitimacy of the transactions on it. This removes reliance on a central party to prove state. Permissionless output proposals go beyond what is required for Stage 1 decentralization.

• Permissionless challenges: If a faulty or fraudulent claim is made (e.g. a malicious attempt to withdraw ETH from the bridge), anyone can challenge it within 3.5 days by running the open-source challenger software included in the OP Stack. Participants who successfully challenge a claim receive the bonds of the invalid claim, creating an economic incentive to help secure the network. This fosters community-driven accountability and control, reducing the need to trust a centralized entity for state verification. With the Fault Proof System, the presence of even a single honest challenger ensures the network will remain secure. To maintain this safeguard, the Base team will operate a challenger continuously.

Together, these changes significantly increase the decentralization of Base and allow anyone to permissionlessly move their funds from Base L2 to Ethereum L1 without relying on any centralized actors.

Next up: Stage 1 decentralization and beyond

Fault proofs are a big step towards Stage 1 decentralization, but we have one more milestone to hit to get there. Today, smart contract upgrades on Base are reviewed and approved by several contributors from the Base and Optimism teams.

Getting to Stage 1 means expanding this set of approvers to a broader, decentralized group of stakeholders — a “security council” — ensuring that Base protocol upgrades are managed without centralized control. Base is on track to complete this final step and achieve Stage 1 decentralization in the coming months.

Looking towards 2025, we’re excited to continue progressing towards full decentralization by taking steps towards Stage 2. Our biggest priority is to support the development of multiple fault proof implementations, such as our recent contributions to standardize L2 state validation and improve compatibility of fault proofs with new execution clients.

With fault proofs now live, we’re excited to continue building on the Base, Superchain, and Ethereum vision of a more decentralized, better internet that is accessible to all.