Hreflang Lens

Description

Inspects the hreflang annotations of the rendered page and validates them against search-engine rules: self-reference presence, x-default fallback, valid BCP-47 language codes and no duplicates. With one click it also runs an optional reciprocity check, fetching the alternate pages to confirm they link back. Born from running federicocalo.dev across 18 languages. Zero telemetry, everything stays in the browser.

Features

• Reads <link rel="alternate" hreflang> from the rendered DOM of the active tab (SPA-friendly)
• Checks the self-reference: the page must point to itself
• Flags a missing x-default annotation
• Validates language codes against BCP-47 (it, en-GB, pt-BR, zh-Hant, es-419, x-default)
• Detects duplicate hreflang for the same language/region
• Optional reciprocity check: fetches alternate pages and verifies they link back
• 100% offline validation, zero telemetry

Required permissions

• activeTab
• scripting

Screenshots

Supported browsers