Raise the HSTS max-age on Netlify

Why it matters

A short HSTS lifetime means browsers forget the HTTPS-only rule quickly, so visitors who return later are exposed again. A lifetime of at least six months, and ideally one year, keeps them protected.

Staged change. Do this in stages and check each one before the next, so a mistake does not break your site or your mail.

The fix

1. Raise the value in your _headers file or netlify.toml and deploy.
2. Check with curl -sI https://example.com/ that the new value is sent, and watch for problems before any further increase.

/*
  Strict-Transport-Security: max-age=31536000

The examples use example.com. Replace it with your own domain.

Read the documentation ↗(opens in a new tab)

Related

• Reported by the HSTS check
• Add the Strict-Transport-Security (HSTS) header
• Fix the malformed Strict-Transport-Security header
• Re-enable HSTS (max-age is zero)
• Decide whether to add includeSubDomains
• Meet the HSTS preload requirements or remove preload
• Consider submitting the domain to the HSTS preload list