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Test scope & comparison notes
These are recorded facts, not a unified ranking. Tested tiers and scope are not consistently recorded. Read pricing with its date and timing with its conditions. Privacy observations reflect visible flows and statements, not a security audit.
Cross-task capability coverage across selected products
Each product is scored independently per task edge; switch tasks below while keeping shared products selected| Task edge | grammarly.com | undetectable.ai | Switch / compare |
|---|---|---|---|
| AI paraphrasing & rewriting | Not tested in topic | 81/100 TXT · Output attached | Compare in task topic → |
| AI content detection | 96/100 JSON · Output attached | 95/100 PDF · Output attached | Active task |
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Browse this task →| Criterion | Grammarly AI content detection 96/100 Seven-aspect task score Grammarly's AI Detector brings the company's trademark engineering polish and friction-free user experience to content authenticity verification. Allowing guest users to scan up to 1,400 words without registration, the cloud pipeline completed evaluation in 7.68s, delivering a calibrated 100.0% AI detection verdict with an elegant semi-circular gauge and zero ad distractions. Tested export JSON · Output attached Historical test · 2026-11-01 | Undetectable AI AI content detection 95/100 Seven-aspect task score Undetectable AI provides multi-model AI content detection and text humanization. During testing, its detection engine accurately classified the AI benchmark sample at 99% AI probability within 0.57s with full sentence breakdown and native PDF export, delivering exceptional detection accuracy and seamless workflow. Tested export PDF · Output attached Historical test · 2026-11-04 |
|---|---|---|
| Pricing & rules | ||
| Pricing plans | Grammarly Free and Pro subscription pricing structure · 2026-10-31 Plan · source date Monthly / one-time Annual bill / period Quota & limits Free2026-10-31 ↗ USD 0/month — Monthly Basic spelling and grammar correction, tone detection, 100 AI prompts/month Basic grammar and spell check, tone detection Pro2026-10-31 ↗ USD 12/month — Monthly One-click sentence rewriting, tone adjustments, unlimited personalized suggestions, plagiarism & AI detection, 2,000 AI prompts/mo Full sentence rewriting, tone adjustments, plagiarism check, AI content detection 2 plan / billing-period records, all listed; — means that period is not recorded. Free tier is permanently free; Pro tier is $12/month with a 7-day free trial and email reminder sent 2 days prior to billing. Cancellation, sources & verification recordCancellation and refund terms unverified Grammarly Plans Official Pricing Page ↗ · 2026-10-31 Capture 1 ↗ | Undetectable AI Free Trial, Monthly, and Annual word-quota subscription plans · 2026-10-31 Plan · source date Monthly / one-time Annual bill / period Quota & limits Free Trial2026-10-31 ↗ Free Free Free 250 words free trial quota for basic AI detection and humanization Basic AI detection and humanization trial 10K Words (Monthly)2026-10-31 ↗ USD 9.99/month — Monthly 10,000 words per month, unlimited AI detection, API compatibility, high quality output AI content detection and text humanization 10K Words (Annual)2026-10-31 ↗ — USD 60/year Annual Billed annually at $60.00 ($5.00/mo equivalent), 10,000 words per month, unlimited AI detection AI content detection and text humanization 20K Words (Monthly)2026-10-31 ↗ USD 19/month — Monthly 20,000 words per month, unlimited AI detection and Human Auto Typer AI content detection and text humanization 20K Words (Annual)2026-10-31 ↗ — USD 114/year Annual Billed annually at $114.00 ($9.50/mo equivalent), 20,000 words per month AI content detection and text humanization 35K Words (Annual)2026-10-31 ↗ — USD 189/year Annual Billed annually at $189.00 ($15.75/mo equivalent), 35,000 words per month AI content detection and text humanization 6 plan / billing-period records, all listed; — means that period is not recorded. Annual plan cards explicitly show the upfront invoice total (e.g. 10K words charged annually $60.00 at $5.00/mo equivalent) alongside monthly original rates ($9.99/mo); free trial is capped at 250 words. Cancellation, sources & verification recordCancellation and refund terms unverified Undetectable AI Official Pricing Page ↗ · 2026-10-31 Capture 1 ↗ |
| Free & trial allowance on the test date | Not verified | Free trial 250 words; paid subscriptions from 10K words/mo |
| Cancellation & refunds | Not verified | Not verified |
| Disclosure of costs & limits | Not verified | Results and probabilities displayed instantly in-page |
| Task quality | ||
| Measured fixture results | AI probability: 100% · Human probability: 0% · Classification label: AI-generated · Confidence calibrated: Yes | AI probability: 99% · Human probability: 1% · Classification label: AI-generated · Confidence calibrated: Yes |
| Fixture findings | Flawless benchmark performance: 100.0% AI probability detection accurately matching ground truth, supporting up to 1,400 words per guest submission, with a 7.68s response time. | Achieved 99% AI detection accuracy with complete sentence highlighting on the benchmark fixture, exporting a native 6.8 KB PDF report in full alignment with ground truth. |
| Original historical observation | Not verified | Input 90-word standard AI anchor fixture (anchor_aidetector_v1/benchmark_sample.txt); Undetectable AI returned 99% AI / GPT probability verdict with sentence highlighting and native PDF export (6.8 KB). |
| Suitable uses · historical assessment | Not verified | Not verified |
| Result & output evidence | ||
| Delivery capabilities | ||
| Recorded export specifications | JSON · Output attached · Check watermark record | PDF · Output attached · No watermark in test |
| Historical specification note · not an official maximum | Semi-circular AI probability gauge + Resembles AI text percentage scale | Full 99% AI probability + sentence highlights + native PDF deliverable |
| Watermark observation | Not verified | No watermark |
| Batch & API | Not verified | Not verified |
| Recorded free-tier dimensions | Not verified | 6.8 |
| Attached file dimensions | Not verified | Not verified |
| Speed & reliability | ||
| Timing observation | Network-observed server wait: 7.68s · End-to-end reference: 7.68s | Network-observed server wait: 0.57s · End-to-end reference: 0.57s |
| Date & fixture | 2026-11-01 · anchor_aidetector_v1 · US-West (California, AS2914) | 2026-11-04 · anchor_aidetector_v1 · US-West (California, AS2914) |
| Repeated tests & reliability | No standardized repetition count, success rate or variability range is recorded. | No standardized repetition count, success rate or variability range is recorded. |
| Interaction experience | ||
| Account requirements | Not verified | No login in this test |
| Sign-in methods | Not verified | Free guest testing supported; Google OAuth and email sign-in |
| Manual adjustment | Not verified | Not verified |
| Interaction observations | Not verified | Direct paste and check workflow with one-click clear and PDF export; zero intrusive popups obstructing detection. |
| Background & reputation | ||
| Service lifecycle notice | Not verified | Not verified |
| Operator | Grammarly, Inc. | Undetectable AI |
| Recorded origin | Not verified | Florida / New York, USA |
| Domain history record | Not verified | Operating since 2023 |
| Background & reputation assessment | Not verified | Registered US entity Undetectable Inc. with wide media recognition, though adversarial detection evasion carries academic ethics controversies. |
| External reputation record | Not verified | Well-known AI detection and humanization platform widely discussed across developer and content creator communities. |
| Engineering & privacy | ||
| Processing location | Processing location unconfirmed | Processing location unconfirmed |
| Third-party tracking record | Google Analytics · Datadog · Cloudflare | Google Analytics · Cloudflare · Hotjar · Meta Pixel |
| Engineering & privacy assessment | Not verified | Protected by TLS 1.3 and Cloudflare security with clear privacy terms. |
| Retention statement | Explicit retention period unconfirmed; inspect policy record | Explicit retention period unconfirmed; inspect policy record |
| Evaluation basis | ||
| Pricing transparency | 32 / 35 Pricing transparently lists monthly rates, annual monthly equivalents, and exact upfront annual totals ($60.00, $114.00, $189.00); free trial limited to 250 words. | |
| Interaction restraint | 27 / 30 Direct paste and check workflow with one-click clear and PDF export; zero intrusive popups obstructing detection. | |
| Background & reputation | 16 / 20 Registered US entity Undetectable Inc. with wide media recognition, though adversarial detection evasion carries academic ethics controversies. | |
| Engineering & privacy | ||
| Task quality | 65 / 65 AI Probability: 100% · Human Probability: 0% · Label: ai · Calibrated: Yes | 65 / 65 AI Probability: 99% · Human Probability: 1% · Label: ai · Calibrated: Yes |
| Deliverable specifications | 18 / 20 Clean unwatermarked export (8/8); Export spec: Semi-circular AI probability gauge + Resembles AI text percentage scale | 18 / 20 Clean unwatermarked export (8/8); Export spec: Full 99% AI probability + sentence highlights + native PDF deliverable |
| Processing speed | 13 / 15 Network-observed server wait: 7.68s (API mode: async_verified; network upload 0s / end-to-end 7.68s shown for reference only, never penalized) | 15 / 15 Network-observed server wait: 0.57s (API mode: sync_json_verified; network upload 0s / end-to-end 0.57s shown for reference only, never penalized) |
