RealWrite vs Undetectable AI: An Honest Comparison

Undetectable AI is the better pick if you want the most words for the least money and an API: its entry plan is $9.99 a month, or $5 billed yearly, for 10,000 words, with up to 5,000 words per run. RealWrite is the better pick if you want to try before you pay, see why a draft reads as AI and make sure the rewrite kept your meaning: it gives 300 free humanizer words every day, explains each flagged sentence and runs a meaning check after every rewrite.

A disclosure: RealWrite is our product. Undetectable AI details come from its pricing page, its terms and its homepage, checked on 21 October 2026.

Side by side

Where Undetectable AI is ahead

Price per word. At the entry level, Undetectable AI is cheaper: $5 a month billed yearly for 10,000 words. Its larger plans scale up to 50,000 words a month.

Long texts in one go. You can paste up to 5,000 words per run, which suits long reports.

An API and a Chrome extension. Useful if you want to humanize inside other tools or in your own app. RealWrite has an API too, but no browser extension yet.

More languages listed. Undetectable AI says it supports 50+ languages, with English the most accurate.

Where RealWrite is ahead

A free tier that renews. Undetectable AI's free option is a one-time 250-word trial. RealWrite gives 300 humanizer words and 500 detector words every day, and 100 words without an account.

It shows its working. RealWrite's AI Detector highlights the sentences that read as AI and says why: uniform rhythm, stock transitions, hedging. You can rewrite one sentence, accept or reject each change and check again.

Your meaning stays yours. A meaning check runs after every rewrite and flags changed numbers, names, quotes and citations. Aggressive humanizing can quietly change what a sentence says; this catches it.

An iPhone app. RealWrite's app, Humanize AI: Paraphrase Tools, is rated 4.7 from more than 3,800 ratings and uses the same account and subscription as the web. We could not find an official iPhone app for Undetectable AI.

Read the terms of both

Undetectable AI's terms say "If you cancel, you will immediately lose your remaining words", and its refund applies only if output "provably flags as less than 75% human on a reputable AI detector". Recent Trustpilot reviews (3.5 from about 1,000) mention unexpected renewals. RealWrite's terms say fees are non-refundable unless otherwise stated, which is why the free daily allowance is there: try it on your own writing before you pay for either.

About "undetectable"

Undetectable AI's name is its promise. Independent research shows why no tool can keep that promise everywhere. A 2026 study found that after Undetectable AI's rewrite, detectors flagged fewer than 4% of AI abstracts, but the same detectors flagged 38% to 80% of lightly edited human text (paper). Another study found Pangram still caught nearly all text from a different humanizer that other detectors missed (paper). Scores depend on which detector, which version and which text.

That is why RealWrite does not promise a score. It helps you make the draft read like a person wrote it, and shows you what changed.

Which one should you choose?

• Choose Undetectable AI if you need a large allowance at the lowest price, long texts per run or a browser extension, and you are comfortable with its cancellation terms.
• Choose RealWrite if you want daily free words, an explained detector, a meaning check and an iPhone app on the same account.

For more options, see the best AI humanizers in 2026 or our RealWrite vs QuillBot comparison.