Difference between Client-side filter and Server-side filters in Cyber Security


Filtering is the process of validating or screening, whether input data given by the user meets the standard format or not. Content filtering is the process of screening emails or web pages that are undesirable. These operate with predefined patterns that include user text string or image data. Recent versions of firewalls include filtering options as built-in features either as hardware or software support. Content filtering is used in cybersecurity as it can block malicious or hacked websites and also block social networking websites as per standard policies defined in corporate organizations.

Filtering methods can be deployed in applications like e-mail, web, and program files to block or filter illegal contents or inappropriate as per policies defined by individuals or organizations or by the government of a country. Applying filters not only restricts the contents but also secures the information from cyber-attacks.

Filtering can be classified into four categories based on the application environment needed by the user

  • Server side filters

  • Client-side filters

  • ISP level filters

  • Search Engine filters

Client Side Filter

A client-side filter is installed on a user's device, but a user cannot modify the contents or install any configurations to it. This sort of restriction is done by password validation or by using administrator privileges so that the end user cannot have information on passwords or access details. This type of filtering is best suited for home security functions and in mid-sized organizations to deploy on specific machines but becomes complex when the size of the company gets increased.

Client-side filtering works in web pages, when a user provides input, it can be validated at the client end itself. There are many possible ways to hack the filtering options on the client side and they can be bypassed in many ways.

Cyber attackers find a few possible ways to bypass the client-side filter and they are −

  • By turning off JavaScript in the browser of a client machine.

  • Modifying or deleting the additional fields which are used to check the user input with the acceptable format.

  • Modifying the file which is uploaded by editing the parameters like MIME, by using specific tools to intercept and modify the data packets.

Server side Filter

This type of filter is present on the server device and installation of it is done by the administrator on a central server machine so that it can be connected to all the client devices. This filtering is used in monitoring the usage of the internet or restricting access to a few social networking web pages in large organizations. Complete control is managed by the organization to apply filtering methods on the server side based on their needs. Providing a different level of access to different user classes is possible in server-side filtering.

As filtering methods are deployed at the server end, hackers cannot bypass them without knowing the features of the filtering options implemented. Consider server-side filtering is applied to a web server application, and when a user sends an input it is forwarded to the server side for validation, if user data is valid then it moves to the next page or does the processing, if it doesn’t match then the error message is displayed with the necessary content.

Here no overhead of processing or validation is done by the browser at the client end and all processing is done on the server side. So, hacking of servers is complex when attackers need to perform any cyber-attacks.

The table below defines the major differences between Client side filter and server-side filter −

Basis of difference

Client-side filter

Server-side filter


Located at the client end and has no options to modify or configure.

Installed at server systems and has full control for validating input.


Client browsers or systems can be hacked and bypassing the filter is possible.

Cannot be hacked as they are located at the server end.

Processing load

Validation of input is done at the client end so the processing load is less.

Validation done at the server end leads to extra overhead as checking the input is made to and from the client and server side.


Filtering methods are stored at the client side for screening or validation process.

Filtering methods are implemented at server devices to ensure better security on inputs received from the client end.

Response time

Faster as the filtering is done on the client device or browser.

As validation happens at the server end and communicating with the client end is also needed, this may increase the response time.


Client-side filtering can be implemented for home users to restrict access to illegal web content.

Used in large organizations to monitor internet usage by employees.


Filtering approaches differ based on the users and where it has to be deployed. Client-side filtering is used at client locations or browsers. Hackers may easily bypass the filtering methods by interrupting or modifying the scripts of webpages, whereas server-side filtering is present in server systems which cannot be accessed easily by the hacker to perform any attacks, as server filtering configurations can be done by the organization as per their security risks.

Updated on: 03-May-2023


Kickstart Your Career

Get certified by completing the course

Get Started