blas.Browser extension
Writing help for Celtic languages
and English.
Catches likely mistakes in Irish, Welsh, Scottish Gaelic, Manx, Cornish, Breton, and English as you type. In Gmail, Notion-style editors, comments, and ordinary text fields. Grammar checking runs on your device. No sign-in required.
Tá mé ag foghlaim gaeilge. Chuaigh sí isteach sa seomra.
Correctness · Mutation
1 / 2After sa, Irish lenites many consonant-initial nouns.
What it catches
Every mistake you learned the hard way.
Mutations
Séimhiú / urú / t-prefix, treiglad meddal / trwynol / llaes. Every trigger word the grammars document.
Case + agreement
Genitive after verbal nouns. Adjective lenition after feminine nouns. Adjective agreement with plurals.
Béarlachas
Calques from English that sound Irish but aren't. "ag lorg do", "ar an gcaoi sin", "i láthair na huaire".
Copula vs. tá
The difference between "Tá sé múinteoir" (wrong) and "Is múinteoir é" (right). Catches the classic learner slip.
Typography + punctuation
Vocative commas, sentence-initial caps, double spaces, smart quotes. Baseline writing issues are checked alongside Celtic-language grammar.
Style warnings
Wordy phrases, long sentences, repeated words. Info-level only. Suggestions, not demands.
How it works.
On-device from the first keystroke. The extension tokenises and tags your text inside the browser itself. Your text never reaches any server, ours, or anyone else's. No network request is made when you type.
A real lexicon, not a wordlist. Irish, Welsh, Scottish Gaelic, Manx, Cornish, Breton, and English checks are backed by local lexicons, published grammar sources, and open linguistic resources. Every rule cites its grammar source, we don't guess.
Inline underlines you can accept or ignore. Each issue is a wavy red line you can hover for an explanation + suggested fix. One click to accept, one click to ignore for the session.
Mac app
Prefer the full app? Get it on your Mac.
The same blas. you use on your phone, built for the Mac. Every lesson, reading, and drill, plus on-device dictation.
Requires macOS 15 or later.
Common questions.
Is it free?
Yes. Free forever. The extension is an acquisition tool for the main blas. app. It has no paid tier and will never hold rules behind a paywall.
Does it send my writing anywhere?
No. Every character you type is processed inside the extension's own service worker. Optional analytics never include text and are off by default. If you link your blas. account, only explicit actions like Save or Report send the text you choose.
Does it work offline?
Yes, entirely. The lexicon and rules ship with the extension. Once installed you can write on a plane with the wifi off and everything still works.
Which dialects does it support?
Irish uses Auto by default, accepting Caighdeán plus common Ulster, Connacht, and Munster forms for validated preposition + article mutation differences. The learning app does not currently offer stricter Irish or Welsh dialect tracks in Settings.
Will it replace a tutor or textbook?
No. It's a writing assistant, not a linguistic authority. For anything you publish or submit, cross-reference against teanglann.ie (Irish) or geiriadur.bangor.ac.uk (Welsh), or a published grammar.
Does it work in Google Docs?
Use the popup paste-to-check flow for Google Docs. Docs uses a custom editor, so inline underlines are disabled there until a reliable adapter is ready.
Is there a Safari version?
Not yet. Chrome, Edge, and Firefox first. Safari conversion is planned after the shared extension code is stable.
Ready when you are.
Adds to your browser in about ten seconds. You can uninstall it just as fast if you don't like it.
Want the full learning app too? Start with blas.