Chrome Extension Permissions Explained

Updated: August 2, 2026 · 7-minute read

Written and maintained by the Chroma AI team at ComfortOne Co., Ltd. — we build the extension this guide describes, and we update these pages as the interfaces change.

You click "Add to Chrome" and a box appears: "Read and change all your data on websites you visit." It sounds alarming, and most people click Add anyway without knowing what they agreed to. This guide explains what these warnings actually mean, which ones genuinely deserve scrutiny, and how to evaluate an extension before you trust it with your browser.

How extension permissions work

An extension declares up front which capabilities it needs. Chrome reads that declaration, translates it into plain-language warnings, and shows them at install time. Two things follow from this that people often miss:

First, the warnings describe capability, not behaviour. "Read and change all your data" means the extension is technically able to do that on the sites it covers. It doesn't tell you whether it does anything of the sort.

Second, the wording is deliberately broad. Chrome errs toward the scariest accurate description, because understating risk would be worse. An extension that only recolours one website still triggers a warning about that website's data.

Site scope: the part that actually matters

The single most useful thing to look at is which sites the permission covers. There's an enormous difference between these two:

• "…on all websites" — the extension runs everywhere, including your bank, your email and your work systems. This is the broadest possible request and deserves real scrutiny.
• "…on chatgpt.com, claude.ai and gemini.google.com" — the extension only runs on those specific sites and is inert everywhere else. Far narrower, and much easier to reason about.

A well-built extension requests the narrowest scope that lets it work. If a tool that only modifies one website asks for access to every website, that gap between purpose and scope is the warning sign — more than the wording of the warning itself.

Common permissions, in plain language

• Host permissions (the "read and change data" warning) — lets the extension see and modify page content on the listed sites. Any extension that visually changes a page needs this for those pages. It's unavoidable for the category, which is why scope matters more than presence.
• storage — saves settings. Usually local to your browser. Low risk; near-universal.
• tabs — can see tab information such as URLs and titles. Often used to detect which site you're on. Reasonable for site-specific tools, more questionable for something that shouldn't care where you are.
• activeTab — temporary access to the current tab, granted only when you click the extension. One of the safest patterns, since it grants nothing until you act.
• scripting — injects code into pages. Required to restyle or modify anything. Again, scope is the question.
• identity — used for sign-in flows such as "Continue with Google." Expected if the product has accounts.
• cookies — read/write cookies. Legitimate in some tools, but worth questioning: cookies include session tokens.
• webRequest / proxy — observe or alter network traffic. Legitimate for ad blockers and privacy tools, and among the most powerful things you can grant. Unexpected in a cosmetic tool.
• <all_urls> — everything, everywhere. Justified for some categories; a red flag for most.

What Manifest V3 changed

Chrome's Manifest V3 platform tightened several things that matter for safety. The most significant is that extensions can no longer fetch and execute arbitrary remote code — the code Chrome reviewed is the code that runs. Under the older platform, an extension could pass review and then quietly load different behaviour later, which is precisely how several well-known extensions turned malicious after being sold.

V3 also encourages narrower, optional permissions and replaced persistent background pages with short-lived service workers. None of this makes extensions automatically safe, but "is this on Manifest V3?" is now a reasonable baseline question, and current store policy requires it.

A five-minute audit before you install

1. Does the scope match the purpose? A theme tool for three AI sites should list three AI sites. Any mismatch between what it claims to do and what it asks for is the main signal.
2. Read the privacy disclosure. Store listings must declare what data is collected and whether it's sold or transferred. Vague or contradictory disclosures are worse than blunt ones.
3. Check who publishes it. A real company or developer with a working website and a contact address is meaningfully better than an anonymous listing. Store badges such as verified-publisher status are useful shorthand.
4. Read the negative reviews specifically. Sort to the low ratings. Complaints about injected ads, redirects or sudden behaviour changes are far more informative than praise.
5. Look at the update history. Abandoned extensions accumulate risk — they're the ones most often sold to new owners who monetise the installed base.

Reviewing what you already have

Most people accumulate extensions and never revisit them. Worth doing occasionally:

• Open chrome://extensions and read the list honestly. Remove anything you no longer use — unused extensions are pure risk with zero benefit.
• Click Details on the ones you keep and check Site access. Many can be narrowed from "On all sites" to "On specific sites" or "On click" without losing the functionality you actually use.
• Prefer On click for tools you use occasionally. The extension stays dormant until you invoke it.
• Be wary of extensions that changed hands. A sudden update with expanded permissions after a long silence is the classic pattern.

How we apply this to Chroma AI

Since this is our site, it's fair to state our own position plainly. Chroma AI requests host access to ChatGPT, Claude and Gemini only — it is inert on every other site, including your bank and your email. It needs that access because restyling a page requires reading and modifying that page; there is no narrower way to change how a website looks.

What it does with that access: applies your chosen colours, background and glass settings. What it does not do: read, store or transmit conversation content, or touch your account credentials. Theme settings live in your browser's local storage. The only server-side data is what you explicitly opt into — themes you choose to share to the gallery, and your sign-in email if you create an account. That's documented in our Privacy Policy, and you can hold us to the same audit checklist above.

Frequently asked questions

Related guides

• About Chroma AI — who we are and what we stand for
• Set up an AI chat workspace for all-day use
• How to change your ChatGPT background
• Frequently asked questions