The best SI humanizer in 2026: an honest comparison

How we compared

We read each tool's homepage, pricing page, terms and privacy policy on September 26, 2026 and noted only what they state publicly. Where a vendor's pages contradict each other, we say so. We did not run detector tests: scores move from week to week and would be out of date before you read this, and we do not think a detector score is the right way to judge writing anyway. The rules we follow for every comparison, including no sponsored placements, are in our editorial policy.

What we looked at, in order of how much it matters to most people:

1. Does the output read well? Test on your own text. Every tool on this list lets you try something for free or for a couple of dollars.
2. Free allowance and words per request. A low per-request cap forces you to cut essays into pieces.
3. Price and refunds. Several tools refund only within 3 days and below a small word count; one says all purchases are non-refundable.
4. Privacy. Some state clearly that text is not stored or used for training, some keep it for weeks, some say nothing.
5. Promises. A tool that guarantees "100% undetectable" is promising something no one controls.

The tools, one by one

SI Humanizer

Our tool. Four focused tools (humanizer, paraphraser, rewriter, summarizer) with styles from Casual to Academic. 3 runs a day without signing up, 3,000 words a day with a free account, text not stored. Weaker than others on: volume per request on the free tier (1,000 words), no Chrome extension or API yet, no built-in detector.

Walter Writes AI

Walter Writes presents itself as an "AI authenticity platform" that makes text "sound like you wrote it" and "scan clean", with "anti-detection technology". Free usage: free trial of 300 words, no credit card. Paid plans from $12/month, or $8/month billed yearly ($96), 750 to 2,000 words depending on plan per request. Strengths: a wide product: humanizer, detector, paraphraser, grammar checker, a Chrome extension and a mobile app under one account. Refunds: first payment only, within 3 days and 1,500 words used; renewals not refundable. Full Walter Writes comparison.

BypassGPT

BypassGPT markets itself as an "Undetectable AI Humanizer" that is "100% Undetectable", can "Bypass Turnitin" and gives a "99%+ Human Score". Free usage: free plan with 150 words a month, 80 words per request. Paid plans from $12/month, or $8/month billed yearly ($96), 80 (free) to 1,000 words; "unlimited" on the top plan per request. Strengths: a permanent free plan, even if small, so you can try it without a card. Refunds: within 3 calendar days and under 1,000 words used; no partial refunds. Full BypassGPT comparison.

Humbot

Humbot positions itself as "Your All-in-One AI Study Assistant" and says its output passes "the strictest AI detectors like Turnitin". Free usage: a free trial for new users (no free plan shown on the pricing page). Paid plans from $11.99/month, or $7.99/month billed yearly ($95.88), 500 to 1,200 words; unlimited on the top plan per request. Strengths: a very broad study toolkit: citations, summaries, translation, math and homework help alongside the humanizer. Refunds: pricing table says 30 days; the refund policy and terms say 7 days and under 1,000 basic or 300 advanced words used. Full Humbot comparison.

StealthGPT

StealthGPT calls itself "The AI Humanizer that actually works" and says "We beat every AI Detector". Free usage: no free allowance stated; paid plans start with a $1 first week for new users. Paid plans from $29.99/month, or $24.99/month billed yearly, 1,000 to 10,000+ words depending on plan per request. Strengths: high per-request limits, useful for long documents. Refunds: all purchases non-refundable; cancellation takes effect at the end of the paid term. Full StealthGPT comparison.

QuillBot AI Humanizer

Part of QuillBot's paraphrasing and grammar suite. The free plan lets you humanize up to 100 words with limited usage; Premium removes the word and usage limit and adds 10+ paraphrasing modes, a plagiarism checker and an AI detector. A good choice if you already use QuillBot.

Grammarly AI Humanizer

Free basic humanization with four preset voices and a custom voice from a writing sample, in six languages. Grammarly states the tool "is not intended to bypass AI detectors", a stance close to ours. Best if Grammarly is already part of your routine.

Undetectable AI

A 250 word free trial, then plans from $9.99 a month for 10,000 words ($5 a month billed yearly), with an AI detector included. As the name says, it is built around detector results. Its pricing FAQ and its displayed prices did not match when we checked, so confirm the price at checkout.

Clever AI Humanizer

Operated by CleverFiles. Free, with up to 3,000 words per request and two writing styles, for English, Spanish and Portuguese input. Its privacy policy says text is sent to outside language model providers, may be read by staff for quality checks and is kept for 30 days.

Phrasly

A $2 pass gives three days of access (up to 50 humanizations a day, 800 words each); the Unlimited plan is $10.99 a month billed yearly with 5,000 words per process, plus plagiarism checking and a content generator.

Our take

There is no single best AI humanizer. If you write a little every day and care about how it reads, start free with SI Humanizer. If you need volume, an API or a big toolbox, the paid tools above are built for that. Whatever you choose, read the output before you use it: a humanizer is an editor, not an author.