Who should use HSTS Checker?

HSTS Checker is a consumer product built for firefox users and web security developers.

Does HSTS Checker have a free plan?

Yes — HSTS Checker is free to use.

What platforms does HSTS Checker run on?

HSTS Checker runs on the web, embeddable surfaces, macOS, Windows, and Linux.

Is HSTS Checker still maintained?

Unverified. HSTS Checker has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.

What are alternatives to HSTS Checker?

Similar projects tracked by PulseGate include HTTPS+ Checker, LH HSTS, and HSTS Ready.

Who makes HSTS Checker?

HSTS Checker is developed by CMD368.

When did HSTS Checker launch?

HSTS Checker first shipped in 2024.

Back to the index

HSTS Checker

Name: HSTS Checker
Author: CMD368

mozilla.orgBrowser DevTools & extensions

HSTS Checker is a Firefox browser extension that scans websites to determine whether HTTP Strict Transport Security is enabled. It is intended for users and web developers who want to verify a site's protection against protocol downgrade attacks.

FreeWebEmbeddablemacOSWindowsLinux

Visit mozilla.org

Overview

4 features

In the Browser DevTools & extensions space, HSTS Checker takes a focused approach. It focuses on checking whether websites use HTTP Strict Transport Security to identify missing browser security protections. It is built as a consumer product for firefox users and web security developers. HSTS Checker is free to use. It runs on the web, embeddable surfaces, macOS, Windows, and Linux.

CMD368 builds and maintains HSTS Checker, and it first shipped in 2024. Among its 4 catalogued features are HSTS detection, website scanning, and browser navigation monitoring. The interface is available in 32 languages, including Czech, German, and Greek.

Summary written by a language model from the project’s public pages.

HSTS detection
Website scanning
Browser navigation monitoring
Security verification

Built with & integrations

Runs on

BrowserEmbeddablemacOSWindowsLinux

Trust & compliance

Verified signals

HTTPSPrivacy Policy Terms of ServiceFree tierMulti-languageStore-verified publisher

Legal

Indexing history

What PulseGate has recorded for this listing

Indexed15 Sep · 08:59 UTC
HSTS Checker verified via Firefox Add-ons
Source: Firefox Add-ons · Open

Frequently asked questions about HSTS Checker

What does HSTS Checker do?: HSTS Checker focuses on checking whether websites use HTTP Strict Transport Security to identify missing browser security protections. It is catalogued under Browser DevTools & extensions on PulseGate.
Who should use HSTS Checker?: HSTS Checker is a consumer product built for firefox users and web security developers.
Does HSTS Checker have a free plan?: Yes — HSTS Checker is free to use.
What platforms does HSTS Checker run on?: HSTS Checker runs on the web, embeddable surfaces, macOS, Windows, and Linux.
Is HSTS Checker still maintained?: Unverified. HSTS Checker has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.
What are alternatives to HSTS Checker?: Similar projects tracked by PulseGate include HTTPS+ Checker, LH HSTS, and HSTS Ready.HTTPS+ Checker LH HSTS HSTS Ready
Who makes HSTS Checker?: HSTS Checker is developed by CMD368.
When did HSTS Checker launch?: HSTS Checker first shipped in 2024.

At a glance

Pricing: Free
Platforms: Web
Built for: Firefox users and web security developers
Model: B2C
Solves: Checking whether websites use HTTP Strict Transport Security to identify missing browser security protections.

Registered as

Firefox Add-ons: hsts-checker

Developer

CMD368

Index record

Indexed: 15 Sep 2026
Lifecycle: Alive
Last seen: 15 Sep 2026

Identity audit (13)

Slug: hsts-checker-mozilla-org
Lifecycle state recorded: 15 Sep 2026
Verification state: Indexed for public listing
Listing state: Listed: yes
Index status: Included in index
Latest evidence snapshot: 15 Sep 2026
Timeline basis: Indexed-at chronology. This listing's first-seen date was written by the catalog backfill, not observed here, so it is not treated as a sighting.
Name from: Derived from the project's own page and URL.
Category from: Assigned by a language model.
Summary from: Written by a language model from public pages.
Languages from: Detected by a language model, checked against the page's own declaration.
Last updated: 15 Sep 2026
Canonical URL: https://addons.mozilla.org/en-US/firefox/addon/hsts-checker

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