AI detectors ranked by the free checks per day the vendor states

Field sorted: the free per day field on each card, written on 9 November 2026 from the free tier field that was read on 8 November 2026 for the first sixteen cards and 9 November 2026 for the twenty-six added that day, each from the vendor page recorded on the card. A card qualifies when the vendor states a free allowance with a per-day unit ("per day", "daily", "in any rolling 24 hours", "maximum 500 a day") counted in checks, scans, credits or operations where one unit is one submission. A per-day allowance stated in characters (Sapling) is tabled apart because a character and a check do not sort on one line; per-month allowances are read from the free tier field into a third table and sorted on the free tiers ranking where they are in words; per-check limits, one-time trials and unlimited tools with no figure are tabled last in the vendor's words. Where a vendor states several daily quotas, the sum is sorted and each quota is printed (SynthID's three tens). Direction: more checks a day rank higher. Tie rule: more study records first, then product name; no tie arises among the seven. 7 of 72 qualify. Full rules: methodology page. The page says which vendor states the most checks a day and never which free tier is the most generous, because a check of 1,200 words and an operation on one image are not the same quantity; the unit is printed in every row.

Vendors state free use in five different units, and most state none. ZeroGPT states words a month (zerogpt.com/pricing, read 8 November 2026), Copyleaks characters a scan (copyleaks.com, read 8 November 2026), Originality.ai words one time (originality.ai/pricing, read 8 November 2026), Pangram checks a day (pangram.com, read 8 November 2026) and Sightengine operations a month with a daily maximum (sightengine.com/pricing, read 9 November 2026). Sapling states two units on two pages: 2,000 characters per check on the web with no cap on checks, and 50,000 characters a day on a new API key (sapling.ai/pricing, read 8 November 2026), so Sapling appears in the characters table and not the ranked one. GPTZero's 10,000 words a month comes from a vendor blog post of 25 October 2026 rather than the pricing page, whose plan cards render by script (gptzero.me/news, read 8 November 2026). All read 8 and 9 November 2026; the Updated line is the date the page last changed.

What the per-day figures leave out

A per-day figure says how often a free account can press the button, not how much it can check. Sightengine's 500 operations are capped again at 2,000 a month, so a team using the full daily allowance exhausts the month in four days (sightengine.com/pricing, read 9 November 2026). Pangram's 20 credits are checks with no published per-check word limit, so the daily word figure is unknown (pangram.com, read 8 November 2026). QuillBot's 6 scans are each capped at 1,200 words, which gives a ceiling of 7,200 words a day, the only one of the four where words a day can be derived from the vendor's two figures (quillbot.com, read 8 November 2026). SynthID's 30 checks are a lookup for a Google watermark, not a classification of arbitrary files (support.google.com, read 9 November 2026). None of the four daily figures comes with a study of the free tier itself; the records on Pangram and QuillBot scored the product, not the quota.

QuillBot's 6 scans a day run without a sign-up under 1,200 words and Pangram's 20 credits start after signing up; the no-account view, added 9 November 2026, lists the 15 cards whose vendor states a check with no account.

Detecting-AI.com

• Verdict: Fits readers who want hundreds of free checks a day with no account.
• Value: 300 checks a day: the Free plan reads "$0 forever, No account required, Up to 300 detections per day, 15,000 characters per check" (detecting-ai.com/pricing, read 10 November 2026); the pricing FAQ adds that no payment card is needed.
• Best for: Editors and moderators checking many short texts in a day.
• Main limitation: Each free check is capped at 15,000 characters (paid plans state 1,000,000 per scan); no study in the index tested Detecting-AI.com, and its 99% (accuracy) and under-1% false positive claims carry no base.
• Link: Detecting-AI.com card

Paperpal

• Verdict: Fits researchers who need a handful of free manuscript checks a day.
• Value: 5 checks a day of up to 1,200 words each, per the detector page's comparison table (paperpal.com/tools/ai-detector, read 10 November 2026); the pricing page's Free column reads "Preview AI detection".
• Best for: A section-by-section check of an English manuscript.
• Main limitation: 1,200 words per scan and five scans; the pricing page's embedded package data lists an AI_DETECTION 10000 per MONTH allowance the page does not display; no study in the index tested Paperpal.
• Link: Paperpal card

StealthWriter

• Verdict: Fits readers who want a stated daily allowance on a free account.
• Value: 10 checks a day: the Free plan lists "10 AI scans/day" and "1,000 words per input"; the public demo at 500 words states "Daily demo limits apply" with no figure, so the account figure is ranked (stealthwriter.ai/pricing, stealthwriter.ai/ai-detector, read 10 November 2026).
• Best for: A few checks a day of up to 1,000 words each.
• Main limitation: Free inputs stop at 1,000 words, the product is sold beside a humanizer, and no study in the index tested the detector.
• Link: StealthWriter card