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Mozilla tls scanner

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Mozilla observatory tls scanner.

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About Mozilla tls scanner

Mozilla TLS Observatory is a suite of tools for analyzing and inspecting Transport Layer Security (TLS) configurations and X.509 certificates on websites. The suite includes an EV Checker for certificate authorities requesting Extended Validation-enabled root certificates, a Certificate Explainer web UI for parsing X.509 certificate fields, a tlsobs CLI tool for issuing website scans, a tlsobs-api HTTP server for receiving scan requests and displaying results, a tlsobs-runner service for scheduling scans, and a tlsobs-scanner service that performs the actual scanning and analysis.

Scans evaluate a site's certificate chain, trust status across Mozilla, Microsoft, Apple, and Android trust stores, cipher suite configuration, OCSP stapling, and server-side cipher ordering, then compare the results against Mozilla's TLS configuration guidelines (old, intermediate, or modern levels) and produce a letter grade. The tool is written in Go and is available as a Docker image containing the CLI, API, scanner, and runner components, with Kubernetes configuration provided for deployment. A hosted instance is referenced for running scans without local setup.

The project is intended for developers and system administrators who manage TLS-terminating services and want to audit and improve their TLS/certificate configuration against Mozilla's server-side TLS recommendations. The repository is a public archive maintained by Mozilla and was archived by its owner on December 1, 2025, making it read-only.

Key features

  • Scans TLS/SSL configurations of websites and compares them against Mozilla guidelines
  • Analyzes X.509 certificates and checks trust across Mozilla, Microsoft, Apple, and Android trust stores
  • Evaluates cipher suites and grades server configuration (e.g. old/intermediate/modern level, letter grade)
  • CLI tool (tlsobs) and HTTP API for issuing scans and retrieving results
  • Scheduled scanning service (tlsobs-runner) for periodic site checks
  • Available as a Docker container bundling the CLI, API, Scanner, and Runner

Frequently asked questions

Is this project actively maintained?

No, the repository was archived by the owner on Dec 1, 2025 and is now read-only.

What languages or platforms does it support?

It's written in Go and requires Golang 1.15+ to build, and is also distributed as a Docker image (mozilla/tls-observatory).

How do I run a scan?

You can install the tlsobs CLI via Go and scan a hosted service or your own site, or run scans through the Docker container.

Does it provide an API?

Yes, tlsobs-api exposes HTTP endpoints such as POST /api/v1/scan, GET /api/v1/results, and GET /api/v1/certificate for programmatic scanning and result retrieval.

Who is this for?

It's aimed at developers and certificate authorities who want to analyze and compare their site's TLS configuration against Mozilla's security guidelines.

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