Based Rollups

Most Layer 2 rollups today use their own sequencers to order transactions. While this makes them fast, it also makes them reliant on the rollup team's infrastructure. A "based" rollup takes a different approach: it doesn't have its own sequencer at all. Instead, it allows the validators of the Layer 1 chain (the "base" layer) to include rollup transactions directly into their blocks. If you are an Ethereum validator, you can also be a "based sequencer" for any rollup that chooses this design.

The primary benefit of a based rollup is simplicity and maximum security inheritance. Because there is no separate sequencer to manage, there is no risk of the sequencer going offline (liveness risk) or censoring users. It also eliminates the need for complex "forced inclusion" mechanisms that other rollups use to let users exit if a sequencer fails. Essentially, as long as Ethereum is working, a based rollup is working. Furthermore, based rollups naturally solve the "sequencer decentralization" problem because they use the already decentralized validator set of the Layer 1.

For investors, based rollups are an interesting trade-off. On one hand, they are the most "pure" form of scaling because they align perfectly with the Layer 1. On the other hand, they may lack some of the "instant" user experience of rollups with dedicated sequencers, and they don't have a separate sequencer that can capture MEV revenue for the rollup's treasury. This design is being championed by researchers like Justin Drake at the Ethereum Foundation. It represents a "back-to-basics" approach to scaling that prioritizes the long-term integrity of the network over short-term performance gains.