Privacy Policy
Lumen — AI DevTools Assistant (Chrome extension) and lumen-ai.online
Last updated: 25 October 2026
Lumen is an AI assistant that runs inside Chrome DevTools. This policy explains what data the Lumen extension and the lumen-ai.online website collect, how that data is used and stored, and exactly which companies receive it.
Short version: your chat history stays in your browser. Text and page context you send to the AI is passed through our server to an AI provider to produce an answer. We do not sell your data, show ads, or use your data for anything other than running Lumen.
1. Who is responsible
Lumen is operated from the Czech Republic. The operator of Lumen is the data controller for the purposes of the GDPR. Contact: privacy@lumen-ai.online.
2. What data we collect
Account data
When you sign up we collect your e-mail address and an authentication identifier. Sign-in is handled by Firebase Authentication (Google).
Device identifier
The extension generates a random device ID. We use it to enforce the device limit on your account and to prevent abuse. It is not linked to your name or to any advertising profile.
Credits, plans and activation codes
We store your credit balance, credit usage, activation codes and transaction records so that we can run the credit system.
Content you send to the AI
When you send a message, we receive the text of your message and any context you choose to attach. That context can include:
- the HTML, attributes and computed styles of the element selected in the Elements panel,
- console errors and stack traces,
- the URL, title and framework of the inspected page,
- text you have selected on the page,
- code snippets and the output of code you ran with "Run on page".
Page context is sent only when you attach it to a message or use an action such as Quick Fix, Page scan or Smart Console suggestions. Lumen does not send page content in the background.
Data that stays on your device
Your chat history, settings and sign-in session are stored in your browser using Chrome extension storage. Chat history is not uploaded to us. Page errors are captured locally in your browser so they can be shown in the extension. They are transmitted only if you ask Lumen to explain one. To help you debug, the extension also keeps a short in-memory record of the last clicks, key presses (Enter, Escape, Tab, Backspace, Delete only), navigations and scrolls on the inspected page, never including what you type into password fields. This record is shown only to you in the extension and is not sent to us or to any AI provider.
Website
The lumen-ai.online website is served by Cloudflare, which processes technical data such as IP address and request metadata to deliver and secure the site. The website does not use advertising or analytics cookies. Cloudflare may set a strictly necessary security cookie to protect the site against bots. If you sign in on the website, your session is kept in your browser's local storage.
3. How we use data
- to sign you in and keep your account secure,
- to generate AI answers to your requests,
- to count and bill credits and process payments,
- to send service e-mails such as purchase confirmations and password-reset messages,
- to prevent abuse and enforce the device limit,
- to answer support requests.
We do not sell personal data. We do not use it for advertising, and we do not use it to judge creditworthiness or for lending purposes. We do not transfer or use it for anything unrelated to providing Lumen's features.
Legal bases under the GDPR: performance of our contract with you (providing the service), our legitimate interest in security and abuse prevention, and legal obligations such as accounting.
4. Who receives your data
We share data only with the service providers needed to run Lumen:
| Provider | Purpose | Data |
|---|---|---|
| Cloudflare | Hosting, API (Workers), database (D1), website (Pages) | All data described above, as the infrastructure that processes it |
| Google (Firebase Authentication) | Sign-in | E-mail address, authentication identifiers |
| Google (Gemini API) | AI responses when a Gemini model is selected | Your messages and attached context |
| OpenAI | AI responses when an OpenAI model is selected | Your messages and attached context |
| Stripe | Payments (when enabled) | Payment details are entered on Stripe's page and do not reach our servers; we receive confirmation and a reference |
| Resend | Transactional e-mail | E-mail address and the message content |
We may also disclose data if the law requires it. We do not share data with any other third party.
5. AI processing
Your message and any attached context are sent from the extension to our server and forwarded to the AI provider for the model you selected. They are used only to generate your answer. Each provider handles that data under its own API terms and privacy policy. We do not use your content to train our own models.
Our server does not store the text of your prompts or of the AI's answers. For each request it records only the model used, the number of credits charged and the time.
Code suggested by the AI is executed only after you click "Run on page", and only inside the page you are inspecting.
6. Retention and deletion
- Account, credit and device data are kept while your account is active.
- Transaction records are kept for as long as accounting and tax law require.
- Chat history is stored in your browser. You can delete chats at any time in the extension, or remove it all by uninstalling the extension.
To delete your account and the data we hold about you, e-mail privacy@lumen-ai.online. We process deletion requests within 30 days, except for records we are legally required to keep.
7. Security
All communication between the extension, the website and our server uses HTTPS. API keys for AI providers are held on our server and are never included in the extension. Access to the backend is restricted. No system is completely secure, but we take reasonable measures to protect your data.
8. Your rights
If you are in the European Economic Area, the United Kingdom or a similar jurisdiction, you can ask us to give you access to your data, correct it, delete it, restrict or object to its processing, and export it. Contact us at privacy@lumen-ai.online. You can also complain to your national data-protection authority. In the Czech Republic that is the Office for Personal Data Protection (Úřad pro ochranu osobních údajů).
9. Chrome Web Store Limited Use
The use of information received from Chrome and Google APIs adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements. We use this data only to provide and improve Lumen's user-facing features, we do not transfer it to others except as described above, we do not use it for advertising, and humans do not read it except with your consent, for security or abuse investigation, or to comply with the law.
10. Children
Lumen is a developer tool and is not directed at children under 16. We do not knowingly collect data from them.
11. Changes
If we change this policy, we will post the new version here and update the date at the top. For material changes we will also notify you in the extension or by e-mail.
12. Data categories
| Category | What we handle | Why | Shared with |
|---|---|---|---|
| Personally identifiable information | E-mail address | Account, sign-in, purchase confirmations, password reset | Google (Firebase), Cloudflare, Resend |
| Authentication information | Sign-in tokens, device ID, activation code | Authenticate requests, device limit | Google (Firebase), Cloudflare |
| Website content | HTML, attributes and computed styles of the selected element; console errors and stack traces; selected text; page URL and title | Only when you attach it or request an explanation; used to generate the AI answer | Cloudflare, Google (Gemini), OpenAI |
| User activity | Credit usage and request counts | Credit balance, daily limits, abuse prevention | Cloudflare |
| Payments | Purchase reference (card details are handled by Stripe) | Credit packs and plans, when enabled | Stripe, Cloudflare |
13. Why Lumen needs its permissions
- All sites (<all_urls>) — Lumen is a developer tool used on whichever site you are debugging. It reads the selected element and captures console errors on that site. Nothing is sent to us until you attach context or ask for an explanation.
- api.lumen-ai.online — our backend, used for sign-in, credits and AI requests.
- activeTab — access to the page you are currently inspecting.
- storage — saves your chat history, settings and sign-in session in your browser.
- tabs — identifies the inspected tab so the DevTools panel and the page can communicate, and opens the Lumen sign-up page.
- windows — opens Lumen in its own window from the toolbar popup.
Run on page: code suggested by the AI is executed only after you click "Run on page", and only inside the page you are inspecting. Lumen does not load or run remotely hosted code in the extension itself.