Coda One

Coda One is a small set of AI writing tools built around one loop: check a draft, then fix what the check finds. The AI Detector is free with no daily limit and no signup, and it marks the specific phrases that read as machine-written instead of just giving a score. Alongside the detector are an AI Humanizer with 9 writing modes (Standard, Academic, Blog, Formal, Simple plus 4 premium), an AI Rewriter with 8 tones, and a Grammar Checker. All four are available in the browser and in a Chrome extension.

The writing tools are free for 3 runs a day; paid plans from $9.99/month add more words, every mode and brand voices. Built by a small independent team in London.