Best Free AI Detector for Windows & Mac (2026): What Actually Runs on Your Machine
Most "AI detectors" live in the cloud, so the Windows-vs-Mac question is mostly a distraction: any web tool runs identically on both through Chrome or Edge, and only a few ship a native app or browser extension. We sorted the genuinely free options by how they actually run on your machine, so you can pick the one that fits your workflow instead of guessing by operating system.
Best free browser extension: GPTZero
GPTZero ships a Chrome and Edge extension that flags AI text inside docs, emails, and web forms, and its free tier covers 5,000 characters per check with three scans a day — enough for daily student use. Because it is an extension, it installs the same way on Windows and Mac with no extra setup beyond the browser.
The extension is the fastest route to a sentence-level AI check without leaving what you are writing, which is exactly what a Windows or Mac user wants from a "free detector on my machine."
Best zero-setup web check: ZeroGPT
ZeroGPT is fully web-based and free with no signup, so it opens the same way on Windows and Mac — paste text, get a percentage. Its DeepAnalyse engine also offers a Chrome extension if you prefer the in-browser route over a tab.
The catch is accuracy: independent testing puts ZeroGPT well below the top tier on non-native English writing, so treat it as a quick first pass, not a verdict you would defend in a grade dispute.
Best no-account quick check: Writer.com
Writer's AI Content Detector is free, needs no account, and checks up to 1,500 characters per run — handy for spot-checking a paragraph before you commit it. Like the others it is a web tool, so your operating system is irrelevant.
It is lightweight by design: good for a fast "is this sentence suspicious?" read, not for scoring a full thesis where you need explanations alongside the number.
Best free student pick: Scribbr
Scribbr offers a free detector aimed at students that explains its flags instead of dumping a number, and it holds around 90% accuracy in third-party tests. It runs in the browser on either OS, with no paywall on the core check.
For graded work the explanation matters more than the headline score, because it tells you which sentences to rewrite in your own voice before a stricter institutional detector ever sees the draft.
Best for multilingual coverage: Copyleaks
Copyleaks keeps quality across 30-plus languages and layers plagiarism on top, which matters if you write or grade in more than English. It is a cloud tool, so it behaves identically on Windows and Mac through the browser or its API.
If language coverage is the reason you are shopping for a detector rather than a one-off check, Copyleaks extends further than the single-purpose free checkers above.
Best for teams and API: Sapling AI
Sapling's free detector adds a browser extension plus an API, which is the differentiator if you want AI checks inside a team inbox or a document pipeline rather than a manual paste. It is cloud-based, so Windows and Mac users get the same experience.
For an individual the free tier is a solid sentence-level check; for a team the API is what separates it from the otherwise similar consumer tools on this list.
Bottom line
Your operating system is not the constraint — almost every free detector is a browser tab that runs the same on Windows and Mac. Reach for GPTZero's extension if you want checks while you write, ZeroGPT or Writer for instant no-account pastes, and Scribbr when you need the score explained. None of them is a verdict; cross-check anything high-stakes in two tools before you act on it.