Expert Guide

The Best Free AI Detectors in 2026

Seven free AI checkers compared on how much text one scan takes, daily caps, account rules and the cheapest paid step.

Louis CorneloupFounder, Dupple · 920,000+ readers · Updated Oct 2026

Product links may be affiliate links. How we rate 7 tools compared

TL;DR

Short answer: Originality.ai has the most usable free plan here, three scans a day with each scan up to 2,000 words, and its Pro plan costs $12.95/mo billed yearly. For one long text with no account, JustDone takes 15,000 words in a single scan, and ZeroGPT takes 15,000 characters.

Only three of the seven publish a USD upgrade price on the pages we read: Winston AI at $10/mo billed yearly, Sapling at $12/mo billed yearly, and Originality.ai. Free limits were checked on vendor pages in October 2026. We did not test accuracy, so these figures describe allowances, not whether a checker is right.

Key facts7 tools compared: Originality.ai, GPTZero, ZeroGPT, Sapling, JustDone, Winston AI, Grammarly

Updated: October 11, 2026
Top pick: Originality.ai (best for: Freelance editors and publishers who check several pieces a day)
Top pick price as of October 11, 2026: Originality.ai: Free: 3 scans a day, up to 2,000 words each. Pro $12.95/mo billed yearly or $14.95 monthly

7 tools compared: Originality.ai, GPTZero, ZeroGPT, Sapling, JustDone, Winston AI, Grammarly
GPTZero (best for: Teachers and reviewers who need a free first check on a single essay): Free checker up to 10,000 characters per check; an account is needed for longer scans
ZeroGPT (best for: Writers who want the largest free character limit per check): Free checker up to 15,000 characters per scan. Paid MAX and EXPERT tiers: no verified USD price
Sapling (best for: Support and sales teams that check short replies at no cost): Free: up to 2,000 characters a check, batches of 5 files. Pro $25/mo monthly or $12/mo billed yearly

"Free" means three different things in AI detection: a daily scan allowance, a limit on how much text one check takes, or a trial that ends. The number that decides whether a free plan works for real work is the second one.

A 1,500-word article is about 9,000 characters, so it fits in one check on four of these tools and needs five on Sapling.

How we chose: we took seven checkers that offer a free step, read each free allowance on the vendor's own page, and quoted a USD upgrade price only where that page showed one.

Toolradar data: 6 of the 10 top picks in our AI writing ranking have a free plan, out of 128 tools evaluated (October 2026). Free plans are common across AI writing tools, but the limits vary more than the headline suggests.

Top Picks

Based on features, real-world fit, and value for money.

Best Free AI Detectors in 2026: 7 Free Checkers Compared on Scan Limits and Upgrade Cost: 7 tools compared, updated Oct 2026
Tool	Pricing	Best for
Originality.ai	Free: 3 scans a day, up to 2,000 words each. Pro $12.95/mo billed yearly or $14.95 monthly	Freelance editors and publishers who check several pieces a day
GPTZero	Free checker up to 10,000 characters per check; an account is needed for longer scans	Teachers and reviewers who need a free first check on a single essay
ZeroGPT	Free checker up to 15,000 characters per scan. Paid MAX and EXPERT tiers: no verified USD price	Writers who want the largest free character limit per check
Sapling	Free: up to 2,000 characters a check, batches of 5 files. Pro $25/mo monthly or $12/mo billed yearly	Support and sales teams that check short replies at no cost
JustDone	Free first scan up to 15,000 words, no account needed for it. Paid plan: no verified USD price	Students and writers who want the biggest word limit in one free scan
Winston AI	Free 14-day trial with 2,000 credits, no permanent free plan. Essential $10/mo billed yearly, $18 monthly	Writers who want to test a detector for two weeks before paying
Grammarly	Free AI detector, no limit stated on its page. AI detection is a Pro feature; no USD price shown	Writers who already work in Grammarly and want a check in the same editor

Pricing read from each vendor's own published pricing page, checked Oct 2026. Every vendor here publishes a price.

Lowest monthly figure each vendor publishes, checked Oct 2026. A tilde marks a figure the vendor states approximately. Per-seat and usage charges can sit on top of it. 4 of 7 do not publish a comparable monthly price and are left out rather than estimated.

Originality.ai

Top Pick

Best for: Freelance editors and publishers who check several pieces a day

PricingFree: 3 scans a day, up to 2,000 words each. Pro $12.95/mo billed yearly or $14.95 monthly

+A 2,000-word article fits in one free scan, three times a day, which is about 6,000 words of free checking every day

+Pro's 2,000 credits a month cover about 200,000 words at 100 words a credit

−The free plan is AI detection only, with nothing else checked

−Three scans a day cap the free plan at about 6,000 words a day, so a larger backlog means waiting or paying

Visit Originality.ai →

GPTZero

Best for: Teachers and reviewers who need a free first check on a single essay

PricingFree checker up to 10,000 characters per check; an account is needed for longer scans

+10,000 characters per check covers a 1,600-word essay in one go, at six characters a word

+No account is needed below the 10,000-character limit, according to the checker's own page

−Longer documents need a free account, which adds a sign-up step to every long check

−The free checker page gives no daily or monthly count, so heavy volume is hard to plan around

Visit GPTZero →

ZeroGPT

Best for: Writers who want the largest free character limit per check

PricingFree checker up to 15,000 characters per scan. Paid MAX and EXPERT tiers: no verified USD price

+15,000 characters per scan, about 2,500 words at six characters a word

+The free checker page does not state a daily or monthly cap

−A 3,000-word report runs about 18,000 characters and needs two scans

−Paid MAX and EXPERT tiers are named on the site, and no USD price is verified here

Visit ZeroGPT →

Sapling

Best for: Support and sales teams that check short replies at no cost

PricingFree: up to 2,000 characters a check, batches of 5 files. Pro $25/mo monthly or $12/mo billed yearly

+Pro raises the check limit fifty times, from 2,000 to 100,000 characters

+Pro sits between Winston AI and Originality.ai on verified annual list prices

−A 1,500-word article is about 9,000 characters, so the free check needs five scans for it

−Free batches stop at five files, so a folder of drafts runs in smaller groups

Visit Sapling →

JustDone

Best for: Students and writers who want the biggest word limit in one free scan

PricingFree first scan up to 15,000 words, no account needed for it. Paid plan: no verified USD price

+Up to 15,000 words in one scan, about six times the 2,500 words that ZeroGPT's limit covers

+No account is needed for the first scan

−Only the first scan is account-free, so later free checks may need a sign-up

−The paid plan has no confirmed USD price, so its upgrade cost is unknown

Visit JustDone →

Winston AI

Best for: Writers who want to test a detector for two weeks before paying

PricingFree 14-day trial with 2,000 credits, no permanent free plan. Essential $10/mo billed yearly, $18 monthly

+Essential is the lowest verified list price among the paid steps here, on annual billing

+Essential includes 100,000 credits a month, and the trial gives 2,000 to test on your own writing

−The free step ends after 14 days, so there is no ongoing free checker

−A 50% discount code also appears beside its plans, but the prices here are list prices

Visit Winston AI →

Grammarly

Best for: Writers who already work in Grammarly and want a check in the same editor

PricingFree AI detector, no limit stated on its page. AI detection is a Pro feature; no USD price shown

+No new tool to set up for people who already use Grammarly

+Pro includes AI detection, so a paid upgrade needs no second tool

−The free detector page gives no word or character limit, so you find the ceiling by testing

−Its plans page quotes Pro in euros with no USD figure, so it cannot be ranked on price here

Visit Grammarly →

What it is

A free AI detector estimates whether a passage was written by a language model, and gives you a capped amount of checking at no cost. Most free plans cap the text in each check, one caps scans per day, and one is only a trial. The right tool depends on how often you check and how long your longest document is.

If you also work with spoken scripts, our free AI voice generators guide covers the free allowances in that category.

Why it matters

Per-check limits shape the workflow more than the price, which is $0 on every free step here. A checker that takes 2,000 characters forces a 9,000-character essay into five pastes that you merge by hand. A checker that counts words, such as JustDone, takes the same essay in one go.

Check the unit before you trust a limit: 10,000 characters is about 1,600 words, not 10,000.

Key features to look for

Unit of measure

GPTZero, ZeroGPT and Sapling count characters, while JustDone and Originality.ai count words. Six characters is roughly one word, so 10,000 characters is about 1,600 words.

Daily caps

Originality.ai allows three free scans a day, each up to 2,000 words. None of the other free checkers here states a daily cap, which makes the per-check size the limit that matters for them.

Accounts

GPTZero asks for a free account for scans above 10,000 characters. JustDone's first scan needs no account, and its page does not say whether later free scans do. Check before you paste client or student text.

Trials versus free plans

Winston AI's free step is a 14-day trial with 2,000 credits. After that, the paid Essential plan starts, so there is no ongoing free checker there.

USD upgrade prices

Three checkers show a USD upgrade price on the pages we read: Winston AI, Sapling and Originality.ai. The other four show no USD upgrade price, so none is claimed for them.

Pricing

Every free step here costs $0, so the cost question is the first paid step. Winston AI Essential is the cheapest verified paid plan on annual billing, with 100,000 credits a month, although its free step is a 14-day trial.

Sapling Pro sits between it and Originality.ai Pro, which is the most expensive annual step of the three.

The other four cannot be ranked on price here. GPTZero, ZeroGPT and JustDone have paid tiers, but we have no verified USD figure for them, so they are left out of the cost ranking.

Grammarly includes AI detection in Pro and quotes its plan in euros only. Before you pay, check Winston AI's pricing page, Sapling's and Originality.ai's, because list prices move.

Plan	Price	Best for
Originality.ai free	Free	3 scans a day, up to 2,000 words each, AI detection only
Originality.ai Pro, billed yearly	$12.95/mo ($155.40/yr)	2,000 credits a month, where 1 credit is 100 words
Originality.ai Pro, monthly	$14.95/mo	Same 2,000 credits, paid month to month
GPTZero free checker	Free	Up to 10,000 characters per check; an account is needed above that
ZeroGPT free checker	Free	Up to 15,000 characters per scan; no daily or monthly cap stated
Sapling free	Free	Up to 2,000 characters per check, batches of 5 files
Sapling Pro, billed yearly	$12/mo billed yearly	Up to 100,000 characters per check
Sapling Pro, monthly	$25/mo	Same 100,000 characters per check, paid month to month
JustDone free scan	Free	Up to 15,000 words in one scan; no account for the first scan
Winston AI free trial	Free for 14 days	2,000 credits during the trial, then a paid plan
Winston AI Essential, billed yearly	$10/mo ($120/yr)	100,000 credits a month; list price, not the 50% code price
Winston AI Essential, monthly	$18/mo	Same 100,000 credits, paid month to month
Grammarly free AI detector	Free	No limit stated on the detector page
Grammarly Pro	No USD price shown	Includes AI detection; the plans page quotes euros only
GPTZero paid plans	No verified USD price	Paid tiers exist; no USD figure confirmed
ZeroGPT paid plans	No verified USD price	MAX and EXPERT tiers exist; no USD figure confirmed
JustDone paid plan	No verified USD price	Allows up to 15,000 words per check; no USD figure confirmed

Mistakes to avoid

×Counting in words when the checker counts characters. A 2,000-word draft is about 12,000 characters, which takes two checks on GPTZero's 10,000-character limit.

×Reading free as unlimited. None of the seven states an unlimited free check, and Originality.ai caps free scans at three a day.

×Testing with a short sample. A checker judges the text it receives, so a 300-word excerpt from the start of a long piece says little about the whole.

Expert tips

→Measure your longest document in characters before you choose. A 1,500-word article is about 9,000 characters, which fits one check on GPTZero, ZeroGPT, JustDone and Originality.ai.

→Use Winston AI's 14-day trial to test your own writing. Its 2,000 trial credits cover a short test, not a month of checks.

→Write down the limit you saw on the day you tested. Free allowances change without notice, so a date next to each number tells your team when to recheck.

The bottom line

For daily work, Originality.ai (Toolradar profile) gives the clearest free allowance: three scans a day. Its Pro plan is the upgrade to plan for if you outgrow that.

For one long document on a first check, JustDone takes 15,000 words in a single scan with no sign-up needed, and ZeroGPT (Toolradar profile) takes 15,000 characters.

GPTZero (Toolradar profile) is the one to show a reviewer, since its free checker is simple and asks for an account only above 10,000 characters.

Treat any free result as a first pass, not evidence.

Choose the checker whose unit fits your longest document, then read our paid AI detectors comparison before you spend money.

If the text came from ChatGPT, Claude or Gemini, see our ChatGPT, Claude and Gemini reviews and their pricing pages: ChatGPT pricing, Claude pricing and Gemini pricing.

For free AI writing tools, check our AI writing tools ranking.

Cite this: AIpresso, "Best Free AI Detectors in 2026", October 2026.

Frequently asked questions

What is the best free AI detector in 2026?

For repeat use, Originality.ai: three scans a day, each up to 2,000 words, on a free plan. For one long text with no account, JustDone takes 15,000 words in a single scan. Free limits checked on vendor pages in October 2026.

Is there a free AI detector with no word limit?

No. None of the seven states an unlimited free check. Most cap each check in characters, words or credits, and Originality.ai also caps free scans at three a day. Grammarly's page names no limit, so test its ceiling before relying on it.

How many words is 10,000 characters?

About 1,600 words at six characters a word, our conversion for ordinary English prose. A 2,000-word draft is about 12,000 characters, which needs two checks on GPTZero.

What is the cheapest paid step after a free detector?

On list price, Winston AI Essential is the cheapest verified paid step at $10/mo billed yearly ($120 a year), with 100,000 credits a month. Sapling Pro and Originality.ai Pro sit above it on annual billing. Winston's free step is a 14-day trial, not an ongoing plan.

Do I need an account to check a long essay for free?

It depends on the tool. GPTZero asks for a free account for scans above 10,000 characters, while JustDone's first scan needs no account. Check the sign-up rule on the tool's page before you paste a student's or client's text.

Is Grammarly's AI detector free?

Grammarly calls its AI detector free, but AI detection is a Pro feature, and its plans page quotes Pro in euros only. So there is no USD price to compare for Grammarly.

Sources

Prices and plan details come from each vendor's own pricing page, re-checked by the Toolradar pricing tracker.