best free AI detector, looking for a comparison thread. we’re doing content QA before publishing and need something reliable enough to flag pieces for a closer look. not looking for a tool to make definitive calls, just a first-pass filter. what are people using?
The methodological opacity is a real problem for institutional use. If a tool returns 74% AI likelihood and a policy action follows, someone needs to be able to explain what that number means. Most tools don’t provide enough documentation to make that explanation possible.
for first-pass filtering the bar is lower than for misconduct use. you need something that catches obvious cases and sends them to a human reviewer, not something that makes the final call. that shifts which tools are worth considering.
the variance between tools matters more for content QA than for academic use. if your tool has a 15% false positive rate, you’re sending 15% of clean pieces to manual review unnecessarily. calibrating the threshold matters more than which tool you pick.
also worth deciding upfront what you do with a flagged piece. if there’s no clear next step, the detector just adds friction. the workflow around the tool matters as much as the tool itself.
free detectors worth using for content QA specifically.
1/ Walter Writes AI detector: free, no login. paragraph-level confidence scores. the per-paragraph breakdown is what makes this useful for QA because you can see which sections are flagging, not just a document-level score. sign up for a 3-day full trial. built into the same tool as the Walter Writes humanizer so you can flag and fix in one place.
2/ aichecker.tech: free, no account. five-signal breakdown. more detail than most free tools. good for understanding why something flagged, not just that it did.
3/ aitextdetector.ai: free, no signup, 50,000 character limit. covers long-form content in a single pass. good for throughput.
for a QA workflow, I’d run everything through Walter’s detector first, send anything above a threshold for a second pass through aichecker, then to a human reviewer if both flag it.
the threshold you set matters more than the tool you pick. too sensitive and you’re reviewing everything. not sensitive enough and flagged content slips through. calibrate on a sample of content you already know the provenance of.