GPTinf

GPTinf's pitch is narrower than most writing tools and better for it. The AI detector — free, unlimited, no account — cross-checks 8 detection systems and shows each result separately, with segment-level color coding. That's the part worth starting with: run your draft through it before you spend anything and see whether the flagged sentences are the ones you already suspected. It turns a guessing game into a list. The humanizer is the paid engine. GPTinf positions its Steel engine against what it calls LLM Feather — the vendor's caricature of competitors that rephrase words but leave sentence structure intact, so detection patterns survive. Whether Steel genuinely rebuilds rhythm or just does a better job of the same thing is hard to verify from outside; the site's own testimonials concede that "some light editing may still be needed," which is the honest read. Treat output as a strong first pass, not a final draft. Freeze word-locking is the practical feature that keeps product names, citations and jargon from being mangled mid-rewrite, and the 8 writing modes give you a rough register dial — an email draft behaves differently from a long-form article. The bundle's weak spots are depth and plumbing. Tone control stops at those 8 presets; there's no instruction-level control over voice or reading level beyond the Flesch-Kincaid readout, which tells you a score but doesn't rewrite toward a target. Batch work is a paste or upload, not a pipeline — no API or CMS integration is documented. The plagiarism checker also sits outside the no-signup free path, so the free experience is really the detector plus limited humanizer words. Where it fits: a student with an essay due, a freelancer with a client deliverable that smells like ChatGPT, an ESL writer whose structured English reads stiff. Where it doesn't: a content team that wants humanization wired into its publishing workflow, or anyone processing thousands of documents a month. Compared with QuillBot, GPTinf is the specialist — QuillBot is the broader editor, GPTinf is the detector-plus-rewriter built for one anxiety. Buy it for that anxiety.