Privacy Policy

This policy explains what Cortex (“Cortex”, “we”, “us”) collects when you use the website, tools and browser extension at cortex-studytool.app, how we use it, who we share it with and the choices you have. By using Cortex you agree to this policy. If you do not agree, please do not use the service.

Who we are

Cortex is a student writing toolkit operated online. For any privacy question, or to make a request about your data, contact us at support@cortex-studytool.app. We act as the controller of the personal data described here.

What we collect

Content you submit: the text you paste into the Humanize, Detector and Split View tools while a request is processed, the messages you send the support assistant, and an extension capture when you ask for an answer. A writing sample you choose to supply for voice matching is read on our server for that one request, to describe how you write; the sample itself is not stored, and only that description reaches the model. Account data: your name, email address and password (stored only as a secure hash) when you create an account, plus your membership status, usage counts and extension license key. Technical data: basic session information such as an IP address and browser user-agent, used to keep you signed in and to secure the service. Payment data: if you subscribe, our payment processor handles your card details and returns only a customer and subscription identifier that we store. We do not see or store full card numbers.

How we use it

We use your data to run the tools you ask for, to create and maintain your account, to apply plan limits fairly, to take payment for a subscription you choose, to keep the service secure and to respond when you contact support. We rely on your request as the basis for processing the text you submit, on our agreement with you for account and billing data, and on our legitimate interest in a secure, working service for technical data. We do not sell your personal data, and we do not use your submitted writing to train our own models.

Third parties that process data for us

To provide the service we share the minimum necessary data with providers who act on our behalf. This list is rendered from the same record the build checks against the code, so a tool cannot start sending text to a provider without that provider appearing here. Each provider has its own privacy terms. Do not submit confidential or restricted material you are not permitted to share with these processors.

Perplexity

Writes the revision in the humanizer, drafts support replies, and produces extension answers.

Receives: The paragraphs you ask Cortex to revise, with quotations, citations, code, equations, links, email addresses and any phrases you lock replaced by placeholders first, so those exact characters are not sent. If you supply a writing sample, a short description of your habits derived from it (typical sentence length, contractions, person, register, connectives), never the sample itself. Your support messages. An extension capture when you choose Answer here.

When: Only when you press the button that asks for it. Web search is switched off for revision, so nothing from the web can enter your draft.

GPTZero

Estimates how a detector reads a passage.

Receives: The passage you send to the detector or to Split View.

When: Only when you run a check.

Stripe

Takes payment for a subscription.

Receives: Your card details, entered on Stripe's own form. Cortex receives only a customer and subscription reference.

When: When you subscribe or manage billing.

Vercel

Hosts the website and runs the server code.

Receives: Every request to the site, as any web host does, including your IP address.

When: Whenever you use the site.

Our database provider

Stores account data.

Receives: Your account, plan, usage counts and licence key. Not the text you revise or check.

When: When you have an account.

Vercel Analytics

Counts page views, without cookies.

Receives: Aggregate page-view data.

When: Only after you choose Allow Analytics.

Google Analytics

Measures aggregate traffic.

Receives: Page views and a cookie that recognises a returning browser, with IP anonymisation on and advertising features off.

When: Only after you choose Allow Analytics.

A self-hosted model server

Writes the revision instead of Perplexity, when a deployment is configured to run its own model.

Receives: The same masked paragraphs the revision model receives. Nothing leaves the server Cortex runs on.

When: Only on a deployment that sets LOCAL_LLM_URL. The public site at cortex-studytool.app does not.

WalterWrites

An alternative revision provider Cortex can be configured to use.

Receives: The text you ask Cortex to revise, when a request is routed to it.

When: Not used by default. When a request is served by it, the result says so.

Revision, specifically. 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.

Vercel Analytics is cookieless. Google Analytics is not, and runs with IP anonymisation on and with Google Signals and ad personalisation switched off, so it is not used to build an advertising profile of you.

The Chrome extension

The extension reads the active tab only at the moment you invoke it, and reads the URLs of your open tabs only to detect which AI destinations you already have open. Your licence key, settings and most recent answer are stored in that browser and are not synced. Choosing “copy a prompt” or “send to a tab” transmits nothing to us. Choosing “answer here” sends the capture and your licence key to this service, which passes the capture to Perplexity so the answer can be produced, and counts the run against your allowance. Auto-Writer types text you supplied and transmits nothing. The full extension policy ships inside the package and is linked from its Chrome Web Store listing.

Cookies and local storage

Cortex sets only strictly necessary cookies by default: the session cookies that keep you signed in. These do not require consent. Choosing “Allow Analytics” additionally loads Google Analytics, which sets its own cookies to recognise a returning browser; that is the only situation in which Cortex sets a non-essential cookie. Your theme choice and your cookie choice are saved in your browser's local storage and never leave your device. A draft you have typed into a tool but not yet sent is kept in that tab's session storage, so a reload does not lose it; it is deleted when you close the tab or press Clear, and it is never sent anywhere until you press the button. We set no advertising or cross-site tracking cookies. Optional analytics load only if you choose “Allow Analytics” in the banner, and a browser Global Privacy Control signal is treated as an automatic opt-out. You can withdraw consent at any time by clearing this site's stored data in your browser.

How long we keep it

Text submitted to the tools is processed to return your result and is not retained by Cortex as a stored document after the request completes; the providers named above may retain it under their own terms. Account data is kept while your account is open and for a reasonable period afterward to meet legal, tax and security obligations, then deleted or anonymized. Usage records are kept to operate plan limits and are periodically pruned.

Your rights

Depending on where you live, you may have the right to access, correct, delete, export or restrict the use of your personal data, and to object to certain processing. Residents of the EEA and UK have these rights under the GDPR; residents of California have similar rights under the CCPA/CPRA, and we do not sell or share personal information as those laws define it. To exercise any right, email support@cortex-studytool.app from the address on your account and we will respond within the time the law requires. You may also complain to your local data protection authority.

Children

Cortex is intended for students in higher education and is not directed at children under 13. We do not knowingly collect data from children under 13. If you believe a child has provided us data, contact us and we will remove it.

Security and changes

We use industry-standard measures including encryption in transit and hashed passwords, but no online service can promise perfect security. We may update this policy as the service changes; we will revise the date at the top and, for material changes, provide a clearer notice. Continued use after an update means you accept the revised policy.