Defaults.Exposed › Methodology › v7 registry › HSTS
HSTS
Methodology v7 · canonical ID hsts-header · Web Security · scored · census as of July 28, 2026
Forces the secure padlock every visit so customers can't be downgraded to an insecure connection.
Definition
| Canonical ID | hsts-header |
|---|---|
| Category | Web Security |
| Grade impact | Scored — counts toward the grade |
| Pass | The site sends a Strict-Transport-Security header with a meaningful max-age. |
| Fail | No HSTS header is sent over HTTPS. |
| Example (passing) | Strict-Transport-Security: max-age=31536000; includeSubDomains |
No-data rule: when this check couldn't be determined for a domain (timeout, SERVFAIL, redacted
source) it returns N/A and is excluded from that domain's scoring denominator — "couldn't determine"
is never counted as a failure. "Determined absent" is a real fail.
Prevalence across the census
19.1% of HTTPS-serving domains send an HSTS header (40,232,423 of 210,439,319, as of July 28, 2026).
Census denominator: 275,666,275 graded domains; this check is measured against the HTTPS-serving subset (210,439,319). Aggregates only — never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/en/fix/hsts
Cite this check
Defaults.Exposed, "HSTS (hsts-header)", Grading Methodology v7 (census as of July 28, 2026). https://defaults.exposed/methodology/v7/hsts-header
Permalink: https://defaults.exposed/methodology/v7/hsts-header ·
All 34 checks: v7 registry ·
Machine-readable: checks.json ·
Licence: open data