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Clever AI Humanizer 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); Clever AI Humanizer does not. Both have a free tier. Only Undetectable AI ships a public API.

Clever AI HumanizerFree rewriter for AI-generated text, up to 3,000 words a pass, in English and Spanish.Undetectable AIRewrites machine-written drafts to read human, with detection scoring built in

Side by side

FactClever AI HumanizerUndetectable AI
CategoryAI Detection & HumanizersAI Detection & Humanizers
Pricing modelFreeFreemium
Starts at—$9.99 month
Public APINoYes
PlatformsWebWeb, API, Chrome Ext
CompanyCleverFiles Inc.Undetectable Inc.
Launched—2023
Last verifiedSep 6, 2026Sep 6, 2026

What our research says

Clever AI Humanizer

A free humanizer with an actual named US company behind it, which puts it a step above the anonymous crowd in this category. The 3,000-word window and change highlighting make it practical for editing rather than blind pasting. Two languages only, and being free with no visible revenue means no promises about uptime or longevity.

Pros

  • Up to 3,000 words per request, larger than most free tiers allow
  • Highlights the changes it made instead of returning an opaque block
  • Three rewrite styles: Normal, Clear & Structured, Simple Formal
  • Named operator — CleverFiles Inc., New Castle, Delaware — with file upload and run history

Cons

  • English and Spanish only
  • No API, no browser extension, no mobile app
  • Free with no stated business model, so continuity is uncertain
  • Rewriting to defeat detectors remains a policy problem wherever detectors are used

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 Clever AI Humanizer if you need

  • Loosening up long machine drafts before you edit them yourself
  • Spanish-language as well as English rewriting
  • Seeing exactly which phrases were changed rather than getting an opaque rewrite

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