We are proposing a Spell Check Custom Dictionary API: a per‑document based, transient dictionary that supplements the browser's built-in spell-checking dictionaries. It does not change how those built-in dictionaries behave. The API lets a web page add words to and remove words from the Spell Check Custom dictionary. During spell checking, the browser's spell checker also checks words against this dictionary, so matching words are not flagged for spelling errors. This gives pages a way to programmatically suppress spell-check false positives within their own document, without requiring any action from users.
Spell checkers routinely flag words that are correct within a particular site but unknown to general dictionaries. Examples include: - A Pokémon wiki containing names like Pikachu or Charmander. - A financial analysis dashboard referencing company‑specific product names or tickers. - A medical or scientific tool using specialized terminology. False positives in these contexts are distracting, misleading, and erode user trust. While browsers allow users to add custom words via browser settings panel, there is currently no way for pages to provide a custom dictionary programmatically that applies only within their own context in order to reduce those false positives. Authors need a way to treat domain‑specific words as “known” without requiring user intervention.
Docs: https://github.com/Igalia/explainers/tree/main/spell-check-dictionary https://docs.google.com/document/d/1ND1a1Z4i6kXMHqMwEyRkHSj5VVTWgX5Ya0aNLgVQYGw/edit?tab=t.0#heading=h.kmfizh6cwyy4
Explainers: https://github.com/Igalia/explainers/tree/main/spell-check-dictionary