a topographic field guide No. 001 · Spring Edition

layer‑2.report

A slow, scrolling report on the rollups, the bridges, and the quiet machinery beneath every transaction. Read it like a relief map.

↓ Descend through the layers
field reading +0.00m
36.0214° N · 119.4179° E Terraced paddies, north Yunnan — a working metaphor for stacked execution layers.
02 · The Descent

A timeline carved into the bedrock.

Layer-2 did not arrive in a single announcement. It accumulated. Each milestone below is a sediment line in the rock face — visible now, invisible at the time. Scroll to descend through it.

  1. 2017 Plasma framework proposed A first formal architecture for off-chain execution with on-chain dispute resolution.
  2. 2018 State channels in production Lightning-style payment networks become the first widely deployed L2 primitive.
  3. 2020 Optimistic rollups go live Fraud-proof rollups demonstrate that EVM compatibility scales without leaving the base layer.
  4. 2022 zk-rollups reach maturity Validity proofs eliminate the seven-day exit window. Recursive proofs compress entire epochs.
  5. 2024 Data-availability layers harden Blob space, modular DA, and shared sequencers turn rollups from monoliths into composable surfaces.
  6. 2026 The fee floor settles Median L2 transaction cost drops below the cost of a domestic letter. Bridges become routine plumbing.
State channels Optimistic rollup zk-rollup
03 · The Ecosystem

A canopy of chains, leaning toward the same light.

No single rollup wins. A forest does. Here are the canopy-formers — the chains whose branches now provide shade for the next generation of applications.

◆

Arbitrum

Optimistic · EVM-equivalent

The widest canopy. A mature optimistic rollup with multi-client clients and the longest production track record.

○

Optimism

Optimistic · Superchain

A rootstock. The OP Stack lets new chains share security and sequencing — one trunk, many limbs.

▲

zkSync Era

zk-rollup · LLVM compiler

A lightwell through dense leaves. Validity proofs fold weeks of disputes into seconds of finality.

◇

Starknet

zk-rollup · Cairo VM

A different species — STARK proofs and a non-EVM language, breeding new species of contract.

■

Base

Optimistic · OP Stack

Sapling planted in 2023, now competing with the canopy-formers for sunlight. Rapid user influx, rapid fee compression.

◯

Linea

zk-rollup · type-2

Younger trunk, deep roots. EVM-equivalent at the bytecode level, with proofs aggregated across blocks.

canopy · viewed from beneath A composite showing how distinct rollups now overlap to form a continuous shaded layer.
04 · The Flow

The river measures itself.

Throughput is no longer the headline. Cost is. Below: three readings taken at the headwaters of the rollup ecosystem, each one a season later than the last.

median fee per transfer $0.000 down from $4.20 in 2021 · a 300x compression
throughput, aggregated 0 tps summed across the eight largest rollups, weekly average
value bridged, lifetime $0.0B canonical bridges only · native and wrapped flows excluded
flow state smooth
05 · The Horizon

The ridge is closer than it looks.

By the time fees become invisible, scaling stops being a topic. It becomes the ground we walk on. This is the last page of the report, and the first page of the rest of it.

a ridgeline at dawn The boundary between what scales and what does not, photographed in the last hour before it disappears.