Scribbr AI Detector

An entry in the Humanizer Wiki directory of AI-text detectors.

Strengths

Free with unlimited checks up to a per-submission word limit
Aimed at students with plain-language explanations
Shares an engine with QuillBot's detector

Limitations

Free tier reportedly optimized for older model output
Independent benchmarks report modest accuracy and some false positives
Detection weakens on paraphrased or humanized text

Overview

Scribbr is an academic-support brand best known for proofreading, citation, and plagiarism tools, and its AI detector is aimed at the same student and academic audience. Users paste text and receive an estimate of how likely it is to be AI-generated. Scribbr and QuillBot are both owned by Learneo, and Scribbr’s detector runs on QuillBot’s underlying detection technology, so the two behave similarly.

Accuracy in practice

Scribbr reports better performance from its premium detector than from the free version and does not advertise a single fixed accuracy figure. Independent 2026 benchmarks have measured the free tool catching a modest majority of AI text while also flagging a small percentage of genuine human writing as AI. Reviewers note that the free tier appears tuned toward older model output, which limits its reliability on text from the newest models, and that accuracy falls further on short, paraphrased, or humanized passages. The result is a probability, not proof, and false positives remain a documented risk for non-native English writers.

Summary

Scribbr’s detector is a free, student-oriented option that mirrors QuillBot’s engine. It is convenient for a quick check, but its scores are estimates whose reliability varies with model, length, and editing, and it is not intended to serve as conclusive evidence.