# ethereum/execution-specs

Specification for the Execution Layer. Tracking network upgrades.

Repository: https://github.com/ethereum/execution-specs
Canonical: https://ross.abutalabs.com/products/execution-specs
Language: Python
License: CC0-1.0
License Family: permissive
Last push: 2026-09-03T00:35:37+00:00

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 100, release rhythm 87, longevity 100
- inputs: {"age_days": 2213, "days_push": 0, "days_rel": 6, "gap_med": 42, "n_releases_24m": 8}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1185, forks 502 (observed 2026-09-03T02:15:11.765457+00:00)

## What it is
An executable Python reference implementation of Ethereum's Execution Layer (EELS), including the EVM and consensus-critical behavior, with test cases that generate fixtures for validating execution clients. It also ships a CLI transition tool (`ethereum-spec-evm`) used in client CI and fuzzing setups.

## Use cases
- understand exactly how the Ethereum execution layer behaves
- generate test fixtures to validate an Ethereum execution client
- run an EVM transition tool in client CI
- fuzz Ethereum client implementations against a reference spec
- prototype and review upcoming Ethereum network upgrades
- execute state tests against the EVM specification

## When to choose
- you are building or testing an Ethereum execution client and need a canonical reference
- you want a runnable, readable specification of EVM semantics
- you need to track or implement a new Ethereum network upgrade
- you want to generate consensus test fixtures

## When to avoid
- you need a production Ethereum node or RPC endpoint
- you want a high-performance EVM implementation
- you only need to send transactions or interact with Ethereum from an app

## Facets
- artifact type: library
- maturity: active
- function: interpreter, testing, benchmarking, fuzzing, cli, developer-tools
- domain: blockchain, developer-tools, testing
- platform: python, windows, cli
- tags: ethereum, execution-layer, evm, executable-specification, reference-implementation, consensus, blockchain-clients, test-fixtures, transition-tool, cryptocurrency, algorithms, linux, macos

## Member repositories
- ethereum/execution-specs (main) score 95

## Provenance
- Observed fields: from GitHub, fetched 2026-09-03T02:15:11.765457+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:24:50.058636+00:00, confidence not recorded.
  - readme: https://github.com/ethereum/execution-specs (fetched 2026-09-03T02:15:11.765457+00:00, sha 8646fa80ae94)
- Data as of 2026-08-30T08:39:29.467469+00:00.