User Agent EN
SandVPN · Firefox
Change the identity your browser announces — User-Agent, client hints and navigator properties — always as one coherent set. Per-site rules, a free-form User-Agent field, and a built-in detection diagnostic. No account, nothing collected.
<all_urls>），意味着它可以读取你在任意站点的页面内容，包括已登录的页面。这是许多扩展正常工作的必要条件，但也值得你确认来源可信。
截图
简介
Some sites still refuse Firefox. SandAgent lets you present a different
browser identity — and, unlike most user-agent switchers, it keeps every
related value consistent with the one you chose.
EVERYTHING FROM ONE SOURCE
The User-Agent header and navigator.userAgent are produced from the same
value, so they cannot contradict each other. The same goes for the platform,
appVersion, vendor, the Sec-CH-UA client hints and navigator.userAgentData.
A mismatch between them is the first thing any detection script looks for,
and it is the flaw most user-agent switchers ship with.
TWO KINDS OF PROFILE, CLEARLY LABELLED
Stealth presents you as a different Firefox — a different version, or a
different operating system. Because the engine really is Firefox, nothing
in the environment can contradict the disguise.
Compatibility presents you as Chrome, Edge or Safari. This unblocks sites
that read the User-Agent string, which is what most of them do.
WHAT IT DOES NOT DO
Compatibility profiles do not fool bot-detection systems, and the add-on
says so in its own interface. The TLS and HTTP/2 fingerprints are produced
by Firefox's network stack, below any extension API, and services like
Cloudflare cross-check them against the announced User-Agent. No browser
extension can change that. If you want a quiet browsing experience on
protected sites, the honest answer is to stay on a Firefox profile.
THE RIGHT PROFILE, SITE BY SITE
Keep your real Firefox everywhere and put on a Chrome profile only where you
need it. A rule covers a domain and all its subdomains, and both the headers
and the JavaScript follow it.
YOUR OWN USER-AGENT
Paste any string. SandAgent uses it verbatim and derives the matching values
from it. If it cannot read the string, it says so instead of guessing — no
bundled list of user agents, so nothing ever goes stale.
BUILT-IN DIAGNOSTIC
One click replays, on the current page, the checks a fingerprinting script
would run. It reports what is coherent, what is not, and which engine-level
tells remain out of reach of any extension.
PRIVATE BY DESIGN
No account. No analytics. No telemetry. No data collection of any kind.
SandAgent makes no network requests of its own; it only modifies requests
your browser was already making. Available in English and French.
User Agent 是做什么的
User Agent 是一款面向 Firefox 的开发者工具类扩展，主要用来调试页面、查看样式与请求、测试接口、辅助前端开发。官方对它的介绍是：Change the identity your browser announces — User-Agent, client hints and navigator properties — always as one coherent set. Per-site rules, a free-form User-Agent field, and a built-in detection diagnostic. No account, nothing collected.在Firefox 附加组件商店（AMO）上，它当前版本 2.1，评分 3.29（7 人评价），约 309 名用户。
适合什么人用
从功能定位看，User Agent 更适合前端工程师、测试与需要经常查看页面结构的用户。如果你平时只是偶尔遇到相关需求，用浏览器自带功能也能凑合；但如果这件事每天都发生，装一个专门处理它的扩展通常比手动操作省事得多。需要注意的是它作用于所有网站，装上后建议先观察一两天，确认不影响常用站点的正常使用。
怎么安装 User Agent
- 打开Firefox 附加组件商店（AMO）上的官方页面；
- 点「添加到浏览器」并确认权限提示；
- 装好后在扩展列表里固定图标，方便随时开关。
本站只做索引与介绍，安装包来自官方商店。如果商店页面提示当前地区不可用，说明该扩展未在你所在区域上架。
常见问题
User Agent 是免费的吗？
User Agent 在Firefox 附加组件商店（AMO）免费提供下载。它是浏览器扩展，装上就能直接用，不需要注册账号。
User Agent 安全吗？
它只申请了 0 项权限，范围比较克制，没有申请「读取所有网站数据」这种大权限。
User Agent 支持哪些浏览器？
当前收录的版本来自Firefox 附加组件商店（AMO），适用于 Firefox。同一个扩展在其他商店可能有对应版本，但功能与版本号不一定相同。
怎么卸载 User Agent？
在扩展管理页找到 User Agent，点移除即可。它在本地保存的设置会一起清掉，不会残留数据。
权限清单 来自 manifest.json 原文
站点访问 2
http://*/*https://*/*
接口权限 5
storagetabswebNavigationwebRequestwebRequestBlocking