AI Detector: Check If Text Was Written by AI

What is an AI detector?

An AI detector is a tool that estimates whether a piece of text was written by a human or generated by an AI language model. It looks for statistical and stylistic patterns that are common in machine writing, such as predictable word choices and unusually even sentence lengths, and turns them into a probability score. Teachers use AI detectors to review assignments, editors use them to check submissions, and writers use them to make sure their own work doesn’t read like a chatbot.

How our AI detector works

Single-method detectors are easy to fool and quick to raise false alarms. AI Humanizer Detector uses two independent layers.

1. Language model analysis

A large language model reads your text the way an experienced editor would. It scores each sentence for the hallmarks of generated writing: generic phrasing, formulaic transitions, balanced “on the one hand, on the other” reasoning and tidy summaries, and it weighs them against signs of a human author such as concrete personal detail, idioms and uneven rhythm. It is instructed to stay cautious on short or ambiguous passages.

2. Stylometric statistics

Alongside the model, the detector measures properties of the text directly:

• Burstiness — how much sentence length varies. People mix short and long sentences; AI tends to keep them even.
• Lexical diversity — how varied the vocabulary is across a moving window of words.
• AI phrase density — how often the text uses phrases that language models overuse, like “delve into” or “it’s important to note.”
• Contractions and voice — natural writing uses contractions and first-person detail more often.

The two layers are blended into one score, and each sentence is highlighted so you can see the evidence rather than trust a number. Curious about the science? Read how AI detectors work.

How to read your AI detection score

AI models this detector recognizes

The detector looks for the shared habits of modern language models rather than one vendor’s fingerprint, so it works on text from ChatGPT and GPT-5, Anthropic Claude, Google Gemini, Microsoft Copilot, Meta Llama, DeepSeek, Mistral, and writing apps built on them such as Jasper, Copy.ai and Writesonic.

Accuracy and limits: what an honest AI detector can tell you

Every AI detector makes mistakes. Knowing where they happen makes the score far more useful:

• Short texts are unreliable. Under about 100 words there simply isn’t enough signal.
• Edited AI text is harder to detect. Once a person rewrites sentences, the machine patterns fade.
• Some human writing looks “AI-like.” Formal, formulaic or non-native English writing can score higher than it should. Research has shown that detectors disproportionately flag non-native writers.
• Scores are probabilities, not proof. A detector should start a conversation, never end one.

We cover the research in detail in are AI detectors accurate?

Flagged as AI? Humanize it

If the detector flags text you plan to publish, click Humanize this text in the report. Your text opens in the AI humanizer, which rewrites the flagged patterns while keeping your meaning, and you can check it again in one click.