CodaOne

Right-click any text to see what reads like AI, then rewrite it. Detect, humanize, rewrite, grammar check. Free, no signup. Coda One puts the check-then-fix writing loop into your right-click menu, on any page. Select text, right-click, done — no tab switching, no pasting.

WHAT IT DOES

Detect AI — Names the exact phrases in your text that read like machine writing, and says why each one was flagged: hedging filler, formulaic transitions, stock openers, the flat rhythm language models fall into. You get the phrases, not just a percentage — the number is there if you want it, but it is the weakest thing we measure and we do not dress it up. Unlimited and free, no signup. It reads English-language writing style; it cannot assess Chinese, Japanese or Korean text, and it says so rather than returning a score it cannot stand behind. We publish its real error rates, including a 96% false-negative rate on our own benchmark, at codaone.ai/ai-detector/accuracy.

Humanize Text — Rewrites flagged passages so they read like a person wrote them. Five modes free (Standard, Academic, Blog, Formal, Simple) and four more on a paid plan (Flowing, Informal, Expand, Shorten). We make no claim that it defeats any third-party detector: we have not been able to test against them, because their terms of service forbid automated evaluation, and we would rather say that than publish a number we invented.

AI Rewriter — Says the same thing a different way, in the register you pick. Five tones free (Standard, Fluency, Formal, Casual, Concise), three more on a paid plan (Expand, Academic, Creative). Useful when the detector flags a passage but you would rather reword it than hand it to the humanizer.

Grammar Check — Fixes grammar, spelling and sentence structure. Corrections replace your text in place where the page allows it, and copy to your clipboard where it does not (Google Docs, Notion, Overleaf).