TL;DR
OmniDetect Advantage
AI detection is a tiny add-on to a grammar tool — not their focus or expertise. No sentence-level breakdown, no consensus, no transparency into how scores are calculated.
Grammarly Strength
Grammarly is the world's most popular writing assistant with 30M+ daily users. AI detection is integrated into a tool many people already use.
The Verdict
Grammarly uses one detection model. OmniDetect runs GPTZero + Winston AI + Originality.ai in a single scan and shows you when engines agree — and when they don't. That's the difference between a guess and a diagnosis.
Feature Comparison
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| Feature | OmniDetect | Grammarly |
|---|---|---|
| Detection | ||
| Detection Engines | 3 (GPTZero + Winston AI + Originality.ai) | 1 (Grammarly proprietary) |
| Multi-Engine Consensus | ||
| Sentence-Level Highlighting | ||
| Analysis & Insights | ||
| AI Writing Coach (Advisor) | ||
| Edit & Rescan Loop | ||
| Score Delta Tracking | ||
| Verification Certificate | ||
| Shareable Verify Links | ||
| Privacy & Trust | ||
| No Text Storage (SHA-256 only) | ||
| Pricing & Plans | ||
| Free Tier | 3 scans/day | Basic grammar only (no AI detection) |
| Starting Price | $9.99 / 7 days | $12/month (Premium plan (includes all writing tools)) |
| Weekly Pass Option | ||
Independent Benchmark Data
Based on our 211-sample benchmark with real-world texts. Updated February 2026.
OmniDetect (3-Engine Consensus)
2.5%
FPR
96.1%
TPR
211 real-world samples · 3 independent engines · Updated Feb 2026
Grammarly does not publish independent accuracy benchmarks. OmniDetect provides transparent, verifiable accuracy data.
See full methodology and dataset details →Compare all AI detectors →
Why OmniDetect?
Three engines, one scan
GPTZero, Winston AI, and Originality.ai run in parallel. When all three agree, you know the result is reliable. When they disagree, you know to investigate further.
Know WHY, not just WHAT
Our AI Advisor explains which sentences triggered detection and suggests specific rewrites. Not just a score — actionable guidance.
Pay for a week, not a month
Need it for finals week or a deadline? Our $9.99 7-Day Pass is the only weekly option in the market. No monthly commitment required.
Frequently Asked Questions
Is Grammarly AI detector accurate?
Grammarly's AI detection is a secondary feature within a grammar tool — not their core expertise. It provides no sentence-level breakdown, no consensus verification, and no published accuracy benchmarks. OmniDetect is purpose-built for AI detection with 3 engines and 94.2% verified accuracy.
Can Grammarly detect ChatGPT?
Grammarly has a basic AI detection feature, but it uses a single unspecified model with no published detection rates for specific LLMs. OmniDetect's 3-engine consensus achieves 96.1% true positive rate across all major LLMs including ChatGPT, Claude, and Gemini.
Is there a better AI detector than Grammarly?
For dedicated AI detection, purpose-built tools outperform grammar-tool add-ons. OmniDetect runs GPTZero, Winston AI, and Originality.ai simultaneously, provides sentence-level highlighting, an AI Writing Coach, and starts free — no $12/month grammar subscription needed.