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Grubby AI alternative billed by the month instead of every 4 weeks
Most people looking for a Grubby AI alternative have hit one of three things: the "Monthly" plan that actually charges every 28 days, the 500-word paste limit on Essential, or a refund request that the terms turned down. Each one is a real cost, and each one is easy to check before you switch.
We read Grubby's pricing page, its terms and its guarantee page on September 26, 2026, all in US dollars, and put the numbers next to ours below. Where Grubby wins, which it does on the monthly bill and for heavy writers on yearly billing, we say so.
Meaning kept · Your own text rewritten · Saved to your history, delete any time
The short answer
Undetected.ai is the better Grubby AI alternative if you need volume and whole-document runs, not if you want the lowest bill. Starter is $49 a calendar month for 100,000 words, while Grubby Essential is $19.99 every 4 weeks for 10,000 words, which works out to 13 charges and $259.87 a year against our 12 charges of $49. Per word that is $0.49 per 1,000 on our side against about $2.00 on Essential. Every Undetected.ai plan takes 1,500 words per run; Grubby Essential takes 500. Grubby wins on price, and on yearly billing at high volume: Unlimited at $12.99 a month has no monthly word pool (30,000 words a day fair use), and we top out at 1,000,000 words a month for $99.
Both tools are capable; the differences below are what actually decide it.
Grubby costs less a month on every tier; Undetected.ai costs more, gives ten times Grubby Essential's monthly words, bills by the calendar month, and takes three times Grubby Essential's paste in one run.
Prices we read ourselves
What Grubby AI costs, and what we cost
Read off each vendor's own pricing page on the date shown, not copied from a roundup. Where the yearly rate is cheaper we lead with it, because that is the number buyers compare.
| Undetected.ai | Grubby AI | |
|---|---|---|
| Cheapest paid plan | $24/mo billed yearly ($49 monthly) | Essential $8.99/mo billed yearly ($107.88), or $19.99 billed every 4 weeks, read September 26, 2026 |
| What that carries | 100,000 words/mo across 300 runs, 1,500 words a run | 10,000 words on Essential (500 words per input), 30,000 on Pro at $9.99/mo yearly or $24.99 every 4 weeks, Unlimited at $12.99/mo yearly or $29.99 every 4 weeks (30,000 words a day fair use) |
| Try it before paying | Trial: 3 runs of up to 300 words, once. No free plan. | Yes, a no-cost allowance of 300 words each month |
| Where they win | One pass over your own text, with our AI-pattern score and its reasons | On yearly billing Grubby is very cheap for volume: Pro carries 30,000 words for $9.99 a month, and Unlimited at $12.99 a month costs less than any of our plans and outguns our $99 Scale tier for heavy writers. Its 2,500-word input on Unlimited is also longer than our 1,500-word run |
Grubby AI pricing read September 26, 2026. All figures in USD. Promotional rates move constantly, so confirm on the vendor's own page before you buy. We build one of these tools.
Not sure any of them do what they claim? We published the ten-minute test for whether an AI humanizer actually works, which costs nothing and settles it on your own writing.
Side by side
Undetected.ai vs Grubby AI, honestly
A fair look at what each does well. Both are capable tools. Here is where they differ.
| What matters | Undetected.ai | Grubby AI |
|---|---|---|
| Billing cycle on the monthly option | A calendar month, 12 charges a year | Every 4 weeks (28 days), 13 charges a year, although the toggle says Monthly |
| Entry plan, paid monthly | $49 a month for 100,000 words, 12 charges a year | Essential $19.99 every 4 weeks for 10,000 words ($259.87 a year) |
| Entry plan, paid yearly | $24 a month billed yearly for 100,000 words | Essential $8.99 a month billed yearly ($107.88) for 10,000 words |
| Words per paste | 1,500 words a run on every plan | 500 on Essential, 1,500 on Pro, 2,500 on Unlimited and Enterprise |
| Heavy-volume tier | 1,000,000 words a month at $99 billed yearly. We do not sell an unlimited tier | Unlimited at $12.99 a month billed yearly, 30,000 words a day fair use, which beats us |
| Refund terms | Non-refundable except where the law requires, stated plainly in our terms; cancel anytime and keep access to the end of the billing period | Terms s.8.5: all purchases non-refundable except for price-change cases; a separate Turnitin money-back offer whose own terms we could not find published |
| Best suited for | Writers with steady monthly volume who paste full essays or posts | High-volume writers willing to prepay a year |
Comparison reflects general, publicly understood positioning. Capabilities change, so check each product for the latest.
Why writers pick Undetected.ai
The humanizer that shows its work
A month means a month
Twelve charges a year, on the same date each month. Grubby's 28-day cycle adds a 13th charge, which is why its $19.99 Essential plan costs $259.87 over a year, not $239.88.
1,500 words in one run
Every plan takes 1,500 words in one run, so a typical essay or blog post goes through whole. On Grubby Essential the same 1,500 words is three separate pastes stitched back together.
See what changed
The tool shows our own AI-pattern score before and after the rewrite, with the reasons behind it, so you can judge the result before you copy it anywhere.
Good questions
Grubby AI vs Undetected.ai, answered
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Further reading: Grubby AI review: the 4-week billing, the input caps and the refund terms · Grubby AI refund and cancellation: what the terms allow · Best AI humanizer in 2026 with 18 tools priced side by side · Cheapest AI humanizer: price per 1,000 words compared
Try Undetected.ai on your own text
Paste your own text and read the rewrite next to the original, with our AI-pattern score measured on both before you copy.
Meaning kept · Your own text rewritten · Saved to your history, delete any time