# letsencrypt/acme-spec

ACME Specification

Repository: https://github.com/letsencrypt/acme-spec
Canonical: https://ross.abutalabs.com/products/acme-spec
License Family: other
Last push: 2024-05-23T19:11:57+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 4335, "days_push": 832, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1128, forks 108 (observed 2026-08-28T04:03:41.639179+00:00)

## What it is
The original specification for the ACME (Automatic Certificate Management Environment) protocol used by Let's Encrypt to automate TLS certificate issuance. The repository is deprecated and retained only for historical reference, with active development moved to the IETF working group.

## Use cases
- understand how the ACME protocol works
- implement automated TLS certificate issuance
- research the history of the Let's Encrypt protocol
- find the current ACME specification home
- build a certificate authority client

## When to choose
- studying the historical origins of ACME
- tracing the evolution of the protocol before IETF standardization

## When to avoid
- implementing a current ACME client or server
- needing the up-to-date specification
- building production certificate automation

## Facets
- artifact type: learning-resource
- maturity: abandoned
- function: security, documentation
- domain: security, developer-tools, apis
- platform: -
- tags: acme, lets-encrypt, tls-certificates, specification, deprecated, ietf, web-server

## Member repositories
- letsencrypt/acme-spec (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:41.639179+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 2026-08-30T06:38:33.511148+00:00, confidence not recorded.
  - readme: https://github.com/letsencrypt/acme-spec (fetched 2026-08-28T04:03:41.639179+00:00, sha 79762ad05bd1)
- Data as of 2026-08-30T08:39:29.467469+00:00.