Revise stiff drafts in your own voice, compare the changes, and see how GPTZero reads the result. The score is a signal, not a verdict.
No account, no card, no email.
Start from your own argument, read every change, and treat the detector estimate as context. Your course rules and your sources stay in charge.
Your own rough writing, or something you generated and want to make yours. Cortex works from whatever you have.
Every change is shown, not applied behind your back. A rewrite can shift meaning or add a claim that now needs a source.
Cortex asks GPTZero how the passage reads and marks the sentences that drew attention, sentence by sentence.
What the score can tell you
That some phrasing matches patterns a classifier associates with generated text. Not who wrote it. Detectors disagree with each other, change over time, and flag writing a person created.
How detectors actually workThree tools on the web and one in the browser. Each shows you what it did, so you can judge it before you keep it.
Strips the padding out of a stiff draft while keeping the claim exactly as careful as you made it. Notice that “may” survives the edit. The rewrite does not invent a ridership increase or a research finding.
Revise this draftIt is important to note that the implementation of shaded Shaded waiting areas may potentially improve the experience of bus passengers make waiting for the bus more comfortable.
Asks GPTZero how the passage reads, then marks the sentences that drew attention and explains what a classifier reacted to.
Check a passageOriginal and revision side by side, each scored on its own, so you can see what the edit actually moved.
Compare versionsIn the Chrome extension: drag a box around a question and choose what happens next.
See the extensionThe Chrome extension keeps the whole loop one key away from the page you are on.
Press Alt+Shift+S on any page and drag a box around what you are looking at. No retyping, no tab hunting.
Answer it here, copy a clean prompt, or send it into the AI tab you already have open.
The answer arrives in a panel on the page you were already reading, ready to copy.
Types text you supply into a compatible field at a pace you set, instead of pasting it in one jump. It only ever types what you put in the box, and Esc stops it immediately. Not every editor on the web accepts it.
Previews are drawings of the extension interface, not screenshots, and not a claim that every site is supported. The store listing tracks release status.
Every plan starts with a 7-day trial and no card. Allowances run per 30-day cycle.
Save up to 33% by paying for the year. Semester billing lands in between.
Anyone, for a week
7 days
No card. Everything switched on, capped.
GCSEs, A-levels, AP and IB
/ month
$47.96 billed every four months. Save $12 against monthly.
Undergraduate and taught postgraduate
/ month
$119.96 billed every four months. Save $20 against monthly.
Dissertation and thesis terms
/ month
$211.96 billed every four months. Save $28 against monthly.
Bring your own API key and Cortex stops metering you entirely. Your provider bills you directly, at their rates and their limits.
| Compare | Free trial | High School | College | Pro | BYOK |
|---|---|---|---|---|---|
| Humanized words per month | |||||
| Detector checks per month | |||||
| Capture and Solve runs | |||||
| Split View | Included | Included | Included | Included | Included |
| Chrome extension | Included | Included | Included | Included | Included |
| Priority processing | Not included | Not included | Not included | Included | Not included |
A semester is four months and renews once. A cycle is 30 days from your billing date, and allowances reset each cycle rather than rolling over. Your dashboard shows what is left and when it resets.
Humanize is metered by words. Detect and Capture and Solve are metered by run, and a run that fails is not counted.
Detector results are estimates from GPTZero, not proof of authorship. On BYOK your provider's own rate limits and pricing apply and Cortex does not meter you at all.
No. Cortex does not guarantee passing a detector, a grade or proof of authorship. Check the writing, sources and assignment policy rather than chasing a score.
Only your instructor’s rules can answer that. Ask about the specific assistance you plan to use, and disclose it when required. A tool cannot grant academic permission.
Cortex sends the paragraphs you ask it to revise to Perplexity's API, with web search switched off, and checks every paragraph that comes back before showing it to you. Quotations, citations, code, equations, links and any phrases you lock are replaced by placeholders before sending, so those exact characters never leave Cortex. If Perplexity cannot be reached, a rule-based editor on Cortex's own servers does the work instead, and the result says which one ran. Detection sends the passage to GPTZero. Cortex does not run Turnitin and does not search a plagiarism database. Review the privacy policy before submitting sensitive text.
Up to 300 words for Humanize and 1,000 for Detect, with no account and nothing stored. Plans raise both limits and add a per-cycle allowance; every plan opens with a 7-day trial that asks for no card.
From the Chrome Web Store, once the listing is live. The extension page walks through what it does and exactly what each permission is for. Cortex will not send you to a store search pretending to be a product listing.
Review the wording, check the evidence, and use detector results as context before you submit.
No card required.