# cloudflare/workerd

The JavaScript / Wasm runtime that powers Cloudflare Workers

Repository: https://github.com/cloudflare/workerd
Canonical: https://ross.abutalabs.com/products/workerd
Homepage: https://blog.cloudflare.com/workerd-open-source-workers-runtime/
Language: C++
License: Apache-2.0
License Family: permissive
Last push: 2026-08-26T23:40:01+00:00

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 87, longevity 100
- inputs: {"age_days": 1448, "days_push": 7, "days_rel": 7, "gap_med": 1, "n_releases_24m": 494}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 8640, forks 717 (observed 2026-08-28T04:10:23.956440+00:00)

## What it is
workerd is the open-source JavaScript/Wasm server runtime based on the same code that powers Cloudflare Workers. It can be used as an application server to self-host Workers-compatible apps, for local development and testing, or as a programmable HTTP proxy.

## Use cases
- self-host cloudflare workers applications
- run workers code locally for development and testing
- build a programmable http proxy
- run javascript/wasm server applications outside cloudflare
- test worker scripts before deployment
- host edge-style serverless apps on my own infrastructure

## When to choose
- you need bug-for-bug compatibility with the Cloudflare Workers runtime
- you want to self-host applications written for Workers
- you want realistic local testing instead of Node.js-based simulation
- you need a standards-based JavaScript server runtime with web platform APIs

## When to avoid
- you need to run untrusted code - workerd is not a hardened sandbox
- you want a general-purpose CLI or GUI JavaScript runtime like Node.js
- you need a simple scripting runtime without server capabilities

## Facets
- artifact type: application
- maturity: active
- function: http-server, wasm, rpc, middleware
- domain: web-development, developer-tools, cloud-computing, self-hosted, apis
- platform: windows, cross-platform, cpp, self-hosted
- tags: javascript-runtime, serverless, cloudflare-workers, v8, edge-computing, nanoservices, http-proxy, linux, macos, docker

## Member repositories
- cloudflare/workerd (main) score 95

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:23.956440+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 2026-08-29T17:25:47.020528+00:00, confidence not recorded.
  - readme: https://github.com/cloudflare/workerd (fetched 2026-08-28T04:10:23.956440+00:00, sha 99d57cefa48f)
  - homepage: https://blog.cloudflare.com/workerd-open-source-workers-runtime/ (fetched 2026-08-29T08:26:08.808082+00:00, sha fd4ac35ac2a7)
  - site_page: https://blog.cloudflare.com/tag/developer-documentation (fetched 2026-08-29T08:26:08.818165+00:00, sha 12bb2ca0cd87)
  - site_page: https://www.cloudflare.com/about (fetched 2026-08-29T08:26:08.821864+00:00, sha 966c42a9a06f)
  - site_page: https://developers.cloudflare.com/workers/platform/compatibility-dates (fetched 2026-08-29T08:26:08.820109+00:00, sha 4c1f1989cfd2)
  - site_page: https://developers.cloudflare.com/ (fetched 2026-08-29T08:26:08.823614+00:00, sha 1b8430a97c92)
- Data as of 2026-08-30T08:39:29.467469+00:00.