OP Stack Networks Now Handle 66.8% of Ethereum L2 and L3 Transactions: Why One Open-Source Framework Quietly Won the Scaling War

A Quiet Takeover of Ethereum’s Scaling Stack

If you have used Ethereum recently, there is a good chance your transaction never touched the mainnet directly. New data shows that OP Stack networks handled 66.8 percent of all Ethereum layer-2 and layer-3 transactions, a figure that confirms what many in the ecosystem have suspected for months: the Optimism-built tech stack has quietly become the default infrastructure for Ethereum scaling.

According to a TOKENPOST report published on October 17, 2026, networks built on the OP Stack — the open-source framework originally developed by Optimism and now maintained by the Optimism Collective — now account for roughly two out of every three transactions executed across Ethereum’s layer-2 and layer-3 landscape. That includes major networks such as OP Mainnet, Base, and a long tail of application-specific chains that have adopted the stack because it dramatically reduces the engineering cost of launching a rollup.

Why the OP Stack Won Mindshare

The OP Stack’s rise is not an accident. When Optimism open-sourced its technology and repositioned itself as an infrastructure provider rather than just a single chain, it effectively invited the entire industry to build on its rails. Coinbase took that invitation with Base, which has become one of the busiest networks in the entire ecosystem. Dozens of follow-on projects — from gaming chains to enterprise experiments — followed the same path.

The pitch is simple: spinning up a layer-2 or layer-3 chain used to require a specialized engineering team and months of security review. With the OP Stack, a project can deploy a production-grade rollup in a fraction of the time, inherit battle-tested code, and plug into a shared standard for messaging and liquidity. That convenience has proven irresistible, and the 66.8 percent figure is the clearest quantitative evidence yet of where developers have chosen to concentrate their activity.

The shift matters for Ethereum itself. Layer-2 networks batch transactions and post compressed data back to the mainnet, meaning the more activity that flows through OP Stack chains, the more fee-paying demand ultimately settles on Ethereum. Advocates of the rollup-centric roadmap have long argued that Ethereum’s future is not one chain doing everything, but thousands of chains inheriting its security. The new data suggests that vision is materializing — with a heavy concentration around one particular technology provider.

The Centralization Question

Not everyone celebrates the numbers. Blockchain technology watchers have raised concerns that a single software stack controlling close to 70 percent of layer-2 activity creates a systemic risk profile of its own. If a critical bug were discovered in the OP Stack, it would not affect one network — it would affect most of the ecosystem’s throughput at once. Sequencer centralization adds another layer of concern: many OP Stack chains still rely on a single sequencer operator, meaning transactions can be reordered or censored at that bottleneck even if the underlying settlement remains trustless.

The Optimism Collective has responded by pushing forward on decentralized sequencing and shared standards through its governance process, but critics argue the pace has not kept up with adoption. There is an uncomfortable irony in a movement born to escape platform risk now rebuilding much of its activity on one shared framework. Defenders counter that open-source code is fundamentally different from a closed corporate platform: anyone can audit it, fork it, or contribute fixes, and the Superchain vision explicitly ties participating networks into a shared security and governance standard rather than a corporate walled garden.

What It Means for the Broader Industry

For developers choosing where to build, the practical effect of the OP Stack’s dominance is liquidity gravity. Standards tend to compound: the more chains share the same framework, the easier it becomes to move assets and messages between them, which attracts more builders, which further entrenches the standard. Rival approaches — Arbitrum’s Orbit stack, zkSync’s ZK Stack, and the growing family of validity-rollup frameworks — continue to win meaningful deployments, but the gap in activity share is now wide enough that the question is no longer whether the OP Stack matters, but whether anything will meaningfully challenge it.

For everyday users, the trend is largely invisible and mostly beneficial. Transactions on OP Stack chains typically cost a small fraction of mainnet fees, and the user experience across these networks has converged on familiar wallet flows. The trade-offs — trust in sequencers, reliance on upgrade keys, and the shared-code risk — are abstract until something breaks.

Ethereum itself traded around 2,430 USD on October 17, 2026, down roughly 1.8 percent on the day, with Bitcoin near 81,473 USD and Solana around 104.56 USD, according to CoinGecko data. Market prices reflect the macro mood more than infrastructure fundamentals, but long-term Ethereum thesis watchers increasingly treat layer-2 adoption metrics as a leading indicator of where the network’s value accrual is heading.

The Bottom Line

The 66.8 percent figure is a milestone for the OP Stack and a defining data point for Ethereum’s scaling era. It confirms that the modular blockchain vision — many chains, one settlement layer — is no longer theoretical. It also hands the ecosystem an uncomfortable concentration problem that governance and engineering will need to solve before the next growth wave arrives. For now, the invisible infrastructure beneath a majority of Ethereum transactions has a clear majority owner: an open-source stack that won the developer vote.