Chrome new tab extensions and Firefox new tab extensions seem similar on the surface — they both replace the new tab page. But there are meaningful differences in how they work, what they can do, and the security models behind them.
Technical Differences
Firefox extension API vs Chrome extension API:
Both browsers implement a version of the WebExtensions API. They're largely compatible, but:
- Firefox has some APIs that Chrome doesn't (like Multi-Account Containers' contextual identities)
- Chrome has some APIs that Firefox doesn't or implements differently
- Manifest V3 is implemented differently — Firefox preserves blocking webRequest, Chrome doesn't
For new tab extensions specifically: both use the chrome.tabs API (Firefox supports the chrome namespace for compatibility) and both use newtab_page override. Cross-browser extensions exist, but some features differ.
Extension review process:
- Firefox AMO: Mozilla reviews all extensions. Review can take time but provides an additional trust layer
- Chrome Web Store: Google's review is more automated. Historically, more malicious extensions have appeared on Chrome Web Store
The Account Situation
Chrome's new tab ecosystem is more connected to Google accounts. Several popular Chrome new tab extensions (like Momentum) sync settings via Google account or their own cloud.
Firefox's new tab extensions generally don't require accounts because the Firefox extension ecosystem doesn't assume you're logged into Google. Extensions like Weather & Clock Dashboard work without any account.
Extension Availability
The Chrome Web Store has more new tab extensions because Chrome has a larger market share. The Firefox AMO has a curated selection that's smaller but generally well-reviewed.
Most major new tab extensions (Momentum, Tabliss, Speed Dial) are available on both platforms.
Feature Parity
For weather new tab extensions specifically:
| Feature | Chrome | Firefox |
|---|---|---|
| Weather + forecast | Available | Available |
| World clocks | Available | Available |
| Account-free options | Limited | More options |
| Open source options | Some | Good selection |
| MV3 impact on extensions | Significant (blocking APIs) | Minimal (blocking APIs preserved) |
The MV3 difference is relevant for ad-blocking new tab extensions (extensions that block ads while showing a custom new tab). On Chrome, these are more constrained. On Firefox, they work at full capability.
The Security Difference That Matters
On Chrome, the extension ecosystem (including new tab extensions) can be affected by Manifest V3's restrictions. On Firefox, the extensions have more capability preserved.
For new tab extensions specifically, this doesn't directly matter — a weather/clock extension doesn't block ads. But it reflects a broader difference: Firefox's extension policy is more permissive for developers and more transparent in what extensions can do.
The Practical Choice
If you're choosing between a Chrome new tab extension and a Firefox equivalent:
- Check if the Firefox version exists on AMO: most do
- Verify permissions are appropriate for both versions
- If the extension is open source, the Firefox and Chrome versions are usually the same codebase
Weather & Clock Dashboard is Firefox-only (AMO). If you switch from Chrome to Firefox and want similar weather new tab functionality, it's a direct replacement with better privacy properties than most Chrome alternatives.
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