Undetectable AI is cheaper and broader: plans start at $5/mo billed annually, it adds a detector for text, images, voice, and video, and it offers a money-back guarantee. StealthGPT costs more, from $29.99/mo, but adds 100+ languages, an iOS app, a Chrome extension, and MCP access. Neither can guarantee results on every AI detector.
Choose Undetectable AI if you want a low entry price, a detector that covers more than text, and a refund option if output is still flagged. Choose StealthGPT if you write in several languages, want a mobile app and browser extension, or want to run the humanizer from Claude or Cursor.
| Tool | Starting price | Free access | Limits | Best for |
|---|---|---|---|---|
| Undetectable AI | 10K plan $5/mo billed annually | Free trial limited to 250 words | 10,000 to 50,000 words a month by plan | Writers who want a cheap humanizer plus a detector and extra tools |
| StealthGPT | Pro $29.99/mo | No free plan listed | 50,000 words a month and 1,000 words per request on Pro | Multilingual writers and teams that want mobile and MCP access |
Both tools include an AI detector so you can check a rewrite first. Detector results vary by text and by tool, and the "passes as human" claims come from the vendors. Always review important text yourself and follow any AI-use rules set by your school, employer, or platform.
Price: 10K plan $5/mo, 20K $9.50/mo, 35K $15.75/mo, 50K $21.25/mo (all billed annually); Business on request. Best for: Writers and agencies who want a humanizer, a detector, and extras like a paraphraser and plagiarism checker on one login.
Price: Pro $29.99/mo; Max $49.99/mo; Enterprise $179.99/mo. Best for: Multilingual writers, students, and content teams who want mobile, browser, and MCP access.
Undetectable AI is cheaper per word. Its 50K plan costs $21.25/mo billed annually for 50,000 words a month, while StealthGPT Pro is $29.99/mo for the same 50,000 words. Annual billing makes the gap look larger, so compare monthly rates too.
Undetectable AI offers more. Its detector works on text, images, voice, and video, and it adds a plagiarism checker, paraphraser, and watermark remover. StealthGPT includes a text detector to check a rewrite before you use it.
StealthGPT is broader. It lists 100+ languages, an iOS app, a Chrome extension, and MCP access on every plan. Undetectable AI lists a Chrome extension and API access, but does not highlight a language count or a mobile app.
Undetectable AI offers a money-back guarantee if flagged output is not made human. StealthGPT lets you cancel anytime but lists no equivalent guarantee on its pricing page.
Pick Undetectable AI if you want the lowest price, a refund option, and detection beyond text. Pick StealthGPT if you work across languages, want to humanize from your phone or browser, or want it inside an MCP workflow. For more options, see our AI humanizer tools collection and AI content detectors and plagiarism checkers collection, or read how StealthWriter compares with Undetectable AI, HumanizeAI with Undetectable AI, and StealthGPT with Mask AI.
Which is cheaper, Undetectable AI or StealthGPT? Undetectable AI. Plans start at $5/mo billed annually, against $29.99/mo for StealthGPT Pro.
Do they have free plans? Undetectable AI offers a free trial limited to 250 words. StealthGPT lists no free plan.
Do they guarantee text passes AI detectors? No. Detector results vary by text and tool, and both claims come from the vendors. Undetectable AI offers a money-back guarantee if output is still flagged.
Which supports more languages? StealthGPT supports 100+ languages on every plan.
Are there other humanizers to compare? Yes. StealthWriter, HumanizeAI, and Mask AI are also listed.
See Undetectable AI's full listing → · See StealthGPT's full listing →
Thomas
Founder
Thomas is the founder of AIPick.info and an avid AI enthusiast dedicated to testing and reviewing the latest tools. He believes technology should make life easier and more enjoyable for everyone. Beyond providing practical reviews, Thomas aims to build an uplifting space where AI feels accessible, delivering insights with energy, positivity, and a commitment to helping others innovate with a smile.
