zevm

zevm is a skill for Codex from evmts/tevm. It costs 61 tokens per session (1,816 once invoked), scanned A, original, MIT.

A Zig implementation of Ethereum transaction and block execution with several ways to use it: as a local JSON-RPC node, a proof-verified light client, an embedded library, or a native Node add-on.

In plain words
What is it for?
Use it to run a local or forked development node, process blocks, perform proof-backed reads, embed execution in Zig, C, or Swift, and build native Node integrations.
Why use it?
It provides a native execution component when JavaScript alone is not the required environment, or when verified reads, standalone operation, or C-compatible integration is needed.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it to run a local or forked development node, process blocks, perform proof-backed reads, embed execution in Zig, C, or Swift, and build native Node integrations.

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Install with agentmods
npx agentmods add skills/evmts/tevm/zevm
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.

Any agent
npx skills add evmts/tevm --skill zevm
Clone the repo
git clone --depth 1 https://github.com/evmts/tevm

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for zevm

README.md
[![agentmods](https://agentmods.dev/badge/skills/evmts/tevm/zevm.svg)](https://agentmods.dev/skills/evmts/tevm/zevm)
Your own site
<a href="https://agentmods.dev/skills/evmts/tevm/zevm"><img src="https://agentmods.dev/badge/skills/evmts/tevm/zevm.svg" alt="Measured on agentmods" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,816 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00061 $0.01816
Opus 5 $0.00030 $0.00908
Sonnet 5 $0.00012 $0.00363
Haiku 4.5 $0.00006 $0.00182

Measured today against content hash 78df90f6e2d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

zevm 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 today.

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.

skills/zevm/SKILL.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Zevm

Use the Zevm source checkout and its pinned dependencies. Zevm requires Zig 0.15.2.

Choose the right surface

Zevm is a Zig Ethereum execution implementation with three product surfaces:

Need Surface
Local or forked development RPC zevm --mode trusted, with Ethereum, Anvil, EVM, and txpool namespaces
Proof-verified reads zevm --mode light or the light-client C ABI
Embed execution Import the zevm Zig module, or link libzevm through zevm.h

Use Zevm when native code, a standalone JSON-RPC node, proof-backed light reads, block processing, or a C-compatible library is required. Use Tevm when the caller is JavaScript or TypeScript and needs typed Solidity imports and an in-process viem-compatible client.

Build from source

Run from the Zevm repository root:

zig build --fetch
zig build -Doptimize=ReleaseSafe
zig build c-ffi -Doptimize=ReleaseSafe
zig build c-smoke -Doptimize=ReleaseSafe
Command Output
zig build zig-out/bin/zevm
zig build run -- --mode trusted --host 127.0.0.1 --port 8545 trusted development JSON-RPC node
zig build test default unit and integration test graph
zig build c-ffi zig-out/lib/libzevm.a, platform shared library, and zig-out/include/zevm.h
zig build npm-native local N-API addon at zig-out/npm/native/zevm.node
zig build verify-fast local release-oriented checks

Do not replace build.zig.zon dependency URLs with sibling paths. The package pins Voltaire and Guillotine Mini by URL and hash.

Embed the C ABI

The ABI is handle-based and currently exposes the proof-verified light client. Link the shared library in rc builds unless the host build system also supplies the static library's transitive crypto objects.

#include <stdio.h>
#include "zevm.h"

int main(void) {
    if (zevm_abi_version() != ZEVM_ABI_VERSION) return 1;

    ZevmHandle *handle = zevm_light_init(
        ZEVM_NETWORK_MAINNET,
        "http://127.0.0.1:0/beacon",
        "http://127.0.0.1:0/execution");
    if (handle == NULL) return 2;

    printf("zevm %s, network=%s, status=%d\n",
           zevm_version(),
           zevm_light_network_name(ZEVM_NETWORK_MAINNET),
           zevm_light_status(handle));

    zevm_light_shutdown(handle);
    return 0;
}

Read the full file on GitHub · 142 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. today First seen · 142 lines · 61 tokens per session scan A 78df90f6e2d4

Subscribe to this mod's changes

zevm is a skill published in the GitHub repository evmts/tevm (446 stars, last pushed yesterday), licensed MIT. It adds 61 tokens to every session and 1,816 once invoked, about $0.0003 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 2026-09-07.

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