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StealthGPT vs Undetectable AI

Two fact sheets from our own research, side by side — pricing, platforms, API access and status re-checked by us rather than quoted from the vendors. Undetectable AI publishes a starting price ($9.99); StealthGPT does not. Only Undetectable AI has a free tier. Both ship a public API.

StealthGPTRewrites AI-generated text to slip past AI detectorsUndetectable AIRewrites machine-written drafts to read human, with detection scoring built in

Side by side

FactStealthGPTUndetectable AI
CategoryAI Detection & HumanizersAI Detection & Humanizers
Pricing modelPaidFreemium
Starts at—$9.99 month
Public APIYesYes
PlatformsWeb, API, Chrome ExtWeb, API, Chrome Ext
CompanyXYZ AI Inc.Undetectable Inc.
Launched20232023
Last verifiedSep 6, 2026Sep 6, 2026

What our research says

StealthGPT

The only thing here that competitors do not match is the developer surface — REST API, MCP server and n8n node — so this is the humanizer you pick if you are automating a content pipeline, not the one you pick to write an essay. Everything it sells is a bet on an arms race the detector vendors are also funding.

Pros

  • Genuine developer stack — documented API reference plus an MCP server, which rivals lack
  • Bundled detector lets you check before and after in one place
  • Chrome extension humanizes directly in any text field
  • Enterprise tier handles up to 20,000 words per run

Cons

  • Pricing page is behind a Vercel bot check, so prices cannot be compared without signing up
  • Daily request caps sit behind plans that market themselves as unlimited
  • Rewriting reliably flattens nuance and introduces awkward phrasing that needs an editing pass
  • Positioning around beating Turnitin invites institutional and reputational risk

Undetectable AI

Buy it only if you accept that passing a detector is a moving target: detector vendors retrain constantly, and text that cleared last month can flag next month. As a multi-format detection dashboard it is more defensible than as a bypass tool.

Pros

  • Detector and rewriter run in one pass, so you see which sentences changed and why
  • Coverage extends past text into image, voice, video and document classifiers
  • Browser extension works inside Docs and Gmail rather than a separate tab
  • Entry tier is genuinely cheap at annual rates

Cons

  • Rewrites often flatten voice and add filler to break statistical patterns
  • Detection on short passages is unreliable in both directions
  • Word quotas drain fast because rejected attempts still consume them
  • The free trial caps at 250 words, barely enough to judge output quality

Which one fits

Choose StealthGPT if you need

  • Content operations running bulk rewriting through an API or n8n workflow
  • Non-native English writers softening obviously templated LLM prose
  • Agencies that need humanizing inside an existing WordPress or Zapier stack

Choose Undetectable AI if you need

  • Marketers cleaning up bulk LLM drafts before publishing
  • Editors wanting a second opinion on submitted copy
  • Teams screening images and audio for synthetic origin
  • Non-native writers smoothing register and tone

More comparisons

All Undetectable AI alternatives →Browse all AI Detection & Humanizers →