The User-Agent request header is most commonly used by servers to identify its client’s application type, operating system, software vendor or software version. Based on the User-Agent string, server selects suitable content to be sent in response. For instance, when a website is opened in a mobile device, it usually looks quite compact and different compared to the way it opens in desktop.
Now imagine if your browser allows you to override the User-Agent string, you could see any version of a website you like! All you need to do is to install Requestly extension in your browser and enjoy the fun.
![UserAgent Rule Card](https://app.requestly.in/content/images/documentation/introducing-useragent/useragent-card-highlighted.jpeg)UserAgent Rule Card
You can choose among popular devices like Android Phone, iPhone, tablets or web browsers like Internet Explorer, Safari, etc. Or you may also specify a Custom User-Agent string to experience a specific version of website.
Requestly has a simple rule builder where you specify the source request URL or domain and select type of User Agent. You may also choose whether to override User-Agent only for the website URL or for all HTTP requests originating from that page.
![UserAgent Rule Editor](https://app.requestly.in/content/images/documentation/introducing-useragent/useragent-ruleeditor.jpeg)UserAgent Rule Editor
![UserAgent Select Device](https://app.requestly.in/content/images/documentation/introducing-useragent/ua-selectdevice.jpeg)UserAgent Select Device
![UserAgent Select Browser](https://app.requestly.in/content/images/documentation/introducing-useragent/ua-selectbrowser.jpeg)UserAgent Select Browser
Requestly also allows you to set your custom UserAgent.
![Setting Custom UserAgent String](https://app.requestly.in/content/images/documentation/introducing-useragent/ua-custom.jpeg)Setting Custom UserAgent String
The best part of this extension is that you may run different rules for different websites simultaneously.
Requestly also has a great application in web-development where you usually want to test your website on different platforms.
Please give it a try and share your valuable feedback with us. We will try to improve and help you in best possible way. For further questions, feel free to reach out at email@example.com