# SSLMate/certspotter

Lightweight Certificate Transparency Log Monitor

Repository: https://github.com/SSLMate/certspotter
Canonical: https://ross.abutalabs.com/products/certspotter
Homepage: https://sslmate.com/certspotter
Language: Go
License: MPL-2.0
License Family: copyleft
Topics: certificate-transparency, pki, x509, security, webpki
Last push: 2026-07-29T20:37:23+00:00

## Health v2 (maintenance only)
Score: 75/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 95, release rhythm 35, longevity 100
- inputs: {"age_days": 3688, "days_push": 35, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1169, forks 102 (observed 2026-08-28T04:03:51.110446+00:00)

## What it is
Cert Spotter is an open-source Certificate Transparency log monitor written in Go that alerts you when SSL/TLS certificates are issued for your domains. It runs as a lightweight daemon without requiring a database, using a robust certificate parser to avoid missing certificates.

## Use cases
- detect unauthorized ssl certificates issued for my domain
- monitor certificate transparency logs for subdomain takeover
- get alerted when a certificate is issued for my domain
- detect compromised certificate authority impersonating my site
- audit certificates issued outside corporate policy
- monitor ct logs without running a database

## When to choose
- you need continuous CT log monitoring for your domains with email or script alerts
- you want a lightweight monitor that requires no database
- you need to detect DNS compromise, CA compromise, or subdomain takeover via certificate issuance
- you want a self-hosted alternative to hosted CT monitoring services

## When to avoid
- you need certificate expiration and installation health checks - those are only in the paid hosted service
- you want a web dashboard or Slack notifications out of the box
- you only need one-off certificate searches rather than continuous monitoring

## Facets
- artifact type: cli-tool
- maturity: active
- function: security, monitoring, alerting, parser, cli
- domain: security, developer-tools, networking
- platform: windows, go, cli, cross-platform
- tags: certificate-transparency, pki, x509, tls, ssl-certificates, certificate-monitoring, subdomain-takeover, webpki, command-line, linux, macos

## Member repositories
- SSLMate/certspotter (main) score 75

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:51.110446+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 2026-08-30T06:28:40.073765+00:00, confidence not recorded.
  - readme: https://github.com/SSLMate/certspotter (fetched 2026-08-28T04:03:51.110446+00:00, sha d8d072e08abb)
  - homepage: https://sslmate.com/certspotter (fetched 2026-08-29T12:34:33.383864+00:00, sha a2a33897d472)
  - site_page: https://sslmate.com/about (fetched 2026-08-29T12:34:33.399787+00:00, sha 85889988968f)
  - site_page: https://sslmate.com/pricing (fetched 2026-08-29T12:34:33.393126+00:00, sha f6cc7c6717b4)
  - site_page: https://sslmate.com/pricing/certificates (fetched 2026-08-29T12:34:33.394832+00:00, sha 58aadac1b106)
  - site_page: https://sslmate.com/pricing/certspotter (fetched 2026-08-29T12:34:33.396554+00:00, sha 715cb5e51aed)
  - site_page: https://sslmate.com/pricing/ct_search_api (fetched 2026-08-29T12:34:33.398214+00:00, sha 91bfe3cb6e35)
  - site_page: https://sslmate.com/help (fetched 2026-08-29T12:34:33.402721+00:00, sha 6d5bc781cd67)
  - site_page: https://sslmate.com/help/faq (fetched 2026-08-29T12:34:33.404201+00:00, sha 06826caa6624)
- Data as of 2026-08-30T08:39:29.467469+00:00.