For “check as I type, stop selling me things,” here’s the honest comparison:
LanguageTool (free) — probably what you want. The free browser extension checks grammar, spelling, and basic style in Gmail, docs, anywhere you type. Key differences from Grammarly free: it supports 25+ languages (huge if you ever write in anything besides English), the free tier feels less crippled, and the upsell pressure is noticeably milder. Limits: free checks are capped per text length (fine for emails; long reports need pasting in chunks), and its advanced style suggestions are paid.
Grammarly (free) — still fine, if you ignore the nagging. Its core free checking catches slightly more contextual English errors in my comparisons of the two on identical text, and the tone detector is free. The “12 premium suggestions hidden” banner is the price you pay. If the upselling is what bothers you most, switch; if raw English catch-rate matters most, tolerate it.
The free option nobody mentions: your AI chatbot. For anything longer than an email, pasting into a free chatbot with “Fix grammar and typos only. Do not change wording or tone. List what you changed.” out-catches both extensions and explains its corrections. The extensions win on as-you-type convenience; the chatbot wins on thoroughness. Most people end up with extension-for-email + chatbot-for-documents. (More on AI writing setups: Free AI writing tool for emails and essays — what do you recommend?)
Built-ins have gotten decent too: Word/Outlook’s Editor (free tier) and even browser spellcheck now catch basic grammar — if your needs are truly just typos, you may need nothing at all.
Verdict for your description: install LanguageTool free, uninstall Grammarly, use a chatbot for the long reports. Zero cost, minimal nagging.
Do you write only in English? That changes the recommendation.