Detect GPT-4 AI text in seconds.
AI Checker spots GPT-4 content with sentence-level accuracy. Free detector for GPT-4, GPT-4 Turbo, GPT-4o, and 1 other GPT-4 variants.
Every major GPT-4 version.
- GPT-4
- GPT-4 Turbo
- GPT-4o
- GPT-4o mini
Medium difficulty.
Lightly edited and paraphrased GPT-4 text typically scores 5-15% lower. Heavy human editing reduces confidence further — always review the sentence-level breakdown.
How AI Checker spots GPT-4.
Five fingerprints that GPT-4 leaves behind, even after editing.
- 1Higher coherence than GPT-3.5 but still detectable burstiness pattern
- 2Sophisticated vocabulary used uniformly across paragraphs
- 3Tendency to wrap claims in qualifiers ("generally", "often")
- 4Multi-clause sentences with parallel structure
- 5Strong intro-body-conclusion structure even in short replies
The GPT-4 fingerprint.
GPT-4 is harder to detect than GPT-3.5 because OpenAI specifically trained it to vary sentence structure, but the model still leaves a fingerprint. The giveaway isn't any single sentence — it's the macro structure. GPT-4 reliably produces a thesis sentence, three supporting points, and a synthesis closer, even when the prompt didn't ask for that shape. AI Checker's burstiness signal catches this rhythm at the paragraph level even when individual sentences look human. For GPT-4 Turbo and GPT-4o, accuracy improves slightly because these models have a slightly higher token-probability ceiling that perplexity-based detectors latch onto. The toughest case is GPT-4o with custom "write like Hemingway" system prompts — short punchy sentences fool burstiness, but the lexical fingerprint of repeated GPT vocabulary still triggers. Always check the sentence-level breakdown, not just the headline number.
What GPT-4 writing looks like.
The deployment of large language models in everyday applications has become increasingly prevalent over the past several years. These systems demonstrate remarkable capabilities in text generation, translation, and reasoning tasks, often producing output that is, in many respects, indistinguishable from human writing at first glance. However, careful analysis reveals patterns and tells that can help identify machine-generated content, particularly when the analyzer has access to multiple complementary detection signals.
Frequently asked questions
Is GPT-4 detection free?
Yes. AI Checker offers a free tier for detecting GPT-4 text without signup. The free tier supports up to 10,000 characters per check with full sentence-level breakdown.
How accurate is GPT-4 detection?
On unedited GPT-4 output, AI Checker reaches 95-98% accuracy. Accuracy stays above 90% on lightly edited or paraphrased GPT-4 content. Heavy human editing reduces detection confidence — always review the sentence-level breakdown for nuance.
Can GPT-4 be used in a way that avoids detection?
Heavy paraphrasing and manual editing can lower detection scores, but multi-signal detection (perplexity, burstiness, lexical fingerprinting) usually still catches at least one signal. AI Checker reports a probability rather than a verdict — treat scores as evidence, not proof.
Does AI Checker detect all OpenAI models?
Yes. AI Checker is calibrated for every major model from OpenAI, including the latest variants. We retrain on each major release to keep detection signatures current.
Is my submitted text private?
Yes. Text submitted to AI Checker is processed in memory and is not used to train models. We do not sell or share your content. Free tier submissions are not stored beyond the immediate analysis.
Detect content from other AI models
AI Checker covers every major LLM. Pick a model to see its specific detection profile.
Spot GPT-4 text in your own content.
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