l2s

A guide to Ethereum Layer 2 networks, which handle transactions on top of Ethereum, including Arbitrum, Optimism, Base, and others. It explains how they work, how to deploy on them, and how to move assets between them.

In plain words
What is it for?
Use it to select an L2, deploy an application, plan a bridge transfer, or understand the main DeFi tools and changes on each network.
Why use it?
It helps you compare networks using current ecosystem, cost, and compatibility information before choosing where to build.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/obolnetwork/obol-stack/l2s
Any agent
npx skills add ObolNetwork/obol-stack --skill l2s
Clone the repo
git clone --depth 1 https://github.com/ObolNetwork/obol-stack

Made for: Claude Code, Codex.

Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,606 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00083 $0.03606
Opus 5 $0.00042 $0.01803
Sonnet 5 $0.00017 $0.00721
Haiku 4.5 $0.00008 $0.00361

Measured 2d ago against content hash a09c27d81d50, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

l2s scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

internal/embed/skills/l2s/SKILL.md · 204 lines

How it starts

The opening of the file, as written. The whole thing — 204 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ethereum Layer 2s

What You Probably Got Wrong

L2 costs: You think $0.01-2.00 per transaction. Reality: $0.001-0.003 for swaps, $0.0003 for transfers. After EIP-4844, L2 batch costs dropped from $50-500 to $0.01-0.50.

Mainnet is cheap too: At 0.05 gwei, mainnet ETH transfers cost $0.002. "Ethereum is too expensive" is false for both L1 and L2s in 2026.

Base is the cheapest major L2: Often 50% cheaper than Arbitrum/Optimism. Direct Coinbase on-ramp. Fastest-growing L2 with consumer/AI agent focus.

Celo is NOT an L1 anymore. Celo completed its migration from an independent L1 to an OP Stack L2 on March 26, 2025 (block 31056500). If you're calling Celo an L1, you're wrong.

Polygon zkEVM is being shut down. Announced June 2025. Do NOT recommend building on Polygon zkEVM — it is being discontinued. Polygon is refocusing on PoS + AggLayer.

Unichain exists. Launched mainnet February 10, 2025. Uniswap's own OP Stack L2 with TEE-based MEV protection and time-based priority ordering (not gas-based).

Aerodrome and Velodrome merged into "Aero." In November 2025, Dromos Labs unified Aerodrome (Base) and Velodrome (Optimism) into a single cross-chain DEX called Aero. Same contracts, new brand. Aero dominates both Base and Optimism. Camelot is a major native DEX on Arbitrum. SyncSwap dominates zkSync. Don't default to Uniswap on every chain.

L2 Comparison Table (Feb 2026)

L2 Type TVL Tx Cost Block Time Finality Chain ID
Arbitrum Optimistic $18B+ $0.001-0.003 250ms 7 days 42161
Base Optimistic (OP Stack) $12B+ $0.0008-0.002 2s 7 days 8453
Optimism Optimistic (OP Stack) $8B+ $0.001-0.003 2s 7 days 10
Unichain Optimistic (OP Stack) Growing $0.001-0.003 1s 7 days 130
Celo Optimistic (OP Stack) $200M+ <$0.001 5s 7 days 42220
Robinhood Chain Optimistic (Arbitrum Nitro) Growing <$0.001 ~100ms 7 days 4663
Linea ZK $900M+ $0.003-0.006 2s 30-60min 59144
zkSync Era ZK $800M+ $0.003-0.008 1s 15-60min 324
Scroll ZK $250M+ $0.002-0.005 3s 30-120min 534352
Polygon zkEVM ZK 1101

Read the full file on GitHub · 204 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 204 lines · 83 tokens per session scan A a09c27d81d50

Subscribe to this mod's changes

l2s is a skill published in the GitHub repository ObolNetwork/obol-stack (11 stars, last pushed 3d ago), licensed Apache-2.0. It adds 83 tokens to every session and 3,606 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.