Terms of Service
Use it freely. Use it responsibly.
Effective date: 30 April 2026 · Last updated: 30 April 2026
The short version: You may install and use the Four Line extension free of charge for personal or commercial work. The tool is provided as-is. Don't use it to break laws, infringe on other people's rights, abuse the AI services it embeds, or pretend our software is yours. We reserve the right to update these terms; if we do, the new version will be published at this URL.
1. Acceptance of these terms
By installing, enabling, or using the Four Line browser extension ("Four Line", the "extension", "we", "us"), you agree to these Terms of Service. If you do not agree, please uninstall the extension. The extension is published by Four Line ("we", "us", "our") via the Chrome Web Store.
2. Licence to use Four Line
Subject to your compliance with these terms, we grant you a personal, worldwide, royalty-free, non-exclusive, non-transferable, revocable licence to install and use Four Line for any lawful purpose, personal or commercial. You do not need a paid subscription. The extension's source code, where published, may be subject to a separate open-source licence; the terms of that licence apply to the source code itself in addition to these terms applying to the distributed extension.
3. Acceptable use
Four Line is a workspace for using AI chat services side by side, broadcasting prompts to multiple AIs at once, and keeping a personal library of prompts and notes. Common acceptable uses include:
Comparing the answers of several AI assistants to the same question.
Keeping research, drafts, or scratchpad notes alongside an active AI session.
Saving and reusing well-crafted prompts.
Capturing snippets of webpages into your own notes or prompt library.
4. Things you must not do
You must not use Four Line to, or attempt to:
- Violate any applicable law or regulation, including privacy, data-protection, copyright, trademark, anti-fraud, sanctions, or export-control laws.
- Harass, threaten, defame, or harm any person, or generate content (with the AI services Four Line embeds or otherwise) that does so.
- Generate or distribute malware, spam, phishing material, child sexual abuse material, or content that incites violence.
- Circumvent rate limits, access controls, or terms of service of any AI service the extension lets you open.
- Run automated scraping, mass broadcasting, or load-test workflows that disrupt the AI providers' services or violate their terms.
- Interfere with the operation of the extension, attempt to bypass its security boundaries, or run modified copies that impersonate Four Line in the Chrome Web Store or elsewhere.
- Reverse engineer, decompile, or disassemble portions of the extension that are not made available under an open-source licence, except to the extent expressly permitted by applicable law.
- Resell, sub-license, or distribute the extension as your own product, or remove or obscure attribution to Four Line.
- Use the extension as a component of malware, spyware, ad-injection software, or any product that surveils end users.
5. Your prompts, notes, and content
Four Line operates entirely on your device. We do not receive, store, or process the prompts you type, the notes you save, the AI responses you read, or the URLs of pages you have open. Anything Four Line stores — your tabs, groups, prompt library, notes library, and any images you embed — lives in your own browser.
You retain all rights to anything you write into Four Line. Because we do not collect or transmit any of it, we make no claim of any kind over your prompts, notes, or other content. You are solely responsible for what you do with the AI outputs you generate, including ensuring you have the necessary rights to share or publish them.
6. Third-party AI services
Four Line is not affiliated with, sponsored by, or endorsed by OpenAI, Anthropic, Google, xAI, Moonshot AI, or any other AI provider whose service Four Line lets you open. The AI service names, logos, and trademarks are the property of their respective owners and are used only as factual references to the services Four Line lets you open.
When you sign in to and use one of these services through Four Line, you are entering into a separate agreement with that provider. Their terms of service, acceptable use policy, and privacy policy apply. We are not a party to that agreement and have no responsibility for the content, availability, accuracy, or legality of anything you receive from those services. You are responsible for ensuring your use of each AI service through Four Line complies with that service's own terms.
7. Updates and availability
We may release updates to Four Line via the Chrome Web Store at any time. Chrome typically auto-installs extension updates; you may manage this in your browser settings. We may also discontinue, suspend, or modify any feature of Four Line at any time, with or without notice. We aim for a high quality bar but do not guarantee uninterrupted availability — and because the extension embeds third-party AI services that may change their interfaces unpredictably, individual features such as broadcast may temporarily break until we ship a compatibility update.
8. Disclaimer of warranties
FOUR LINE IS PROVIDED "AS IS" AND "AS AVAILABLE", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, OR NON-INFRINGEMENT. WE DO NOT WARRANT THAT THE EXTENSION WILL BE ERROR-FREE, THAT THE BROADCAST FEATURE WILL CORRECTLY SUBMIT EVERY PROMPT TO EVERY AI SERVICE, THAT THE EMBEDDED AI SERVICES WILL CONTINUE TO ALLOW EMBEDDING, OR THAT IT WILL OPERATE WITHOUT INTERRUPTION OR LOSS.
Outputs returned by AI services may be inaccurate, biased, or unsafe. You are responsible for evaluating the accuracy and appropriateness of any content you receive through Four Line before relying on it. Always verify before publishing.
9. Limitation of liability
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, FOUR LINE AND ITS AFFILIATES, OFFICERS, EMPLOYEES, AND CONTRIBUTORS WILL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, EXEMPLARY, OR PUNITIVE DAMAGES, OR FOR ANY LOSS OF PROFITS, REVENUE, DATA, GOODWILL, OR BUSINESS, ARISING OUT OF OR IN CONNECTION WITH YOUR USE OF (OR INABILITY TO USE) FOUR LINE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. IN NO EVENT WILL OUR AGGREGATE LIABILITY ARISING FROM OR RELATED TO FOUR LINE EXCEED ONE HUNDRED US DOLLARS (US $100), OR THE AMOUNT YOU PAID US FOR FOUR LINE IN THE TWELVE MONTHS PRECEDING THE EVENT GIVING RISE TO THE CLAIM, WHICHEVER IS GREATER.
Nothing in these terms excludes or limits liability that cannot be excluded or limited under applicable law.
10. Indemnification
You agree to defend, indemnify, and hold harmless Four Line from any claim, demand, loss, or damages, including reasonable legal fees, arising from (a) your misuse of Four Line, (b) your violation of these terms, (c) your violation of any AI provider's terms of service while using Four Line to access their service, or (d) your violation of any applicable law or third-party right in connection with your use of the extension.
11. Termination
You may stop using Four Line at any time by uninstalling it from your browser. We may terminate or suspend your right to use Four Line if you breach these terms. Sections that by their nature should survive termination (including disclaimers, limitations of liability, indemnification, governing law) will survive.
12. Governing law
These terms are governed by the laws of the jurisdiction in which Four Line is established, without regard to its conflict-of-laws rules. Any dispute arising from these terms or your use of Four Line will be resolved in the competent courts of that jurisdiction, except where mandatory consumer-protection law in your country of residence grants you the right to bring proceedings locally.
13. Changes to these terms
We may update these terms from time to time. The "Last updated" date at the top of this page reflects the most recent changes. If we make material changes that affect your rights, we will publish the updated terms at this URL and, where reasonably practicable, surface a notice in the extension before the new terms take effect. Continued use of Four Line after the effective date of an update constitutes acceptance of the updated terms.
14. How to reach us
For questions about these terms, write to hello@fourline.ai. For privacy-specific questions, see the Privacy Policy.