An add-on is an additional program or module that supplements browsers, mail programs, and other soft- and hardware applications and adds functionality that the basic system does not have. As an extension for software and hardware, the add-on changes various features of the system into which it is implemented, thereby increasing the range of functions. For example, add-ons can increase security, provide analytics, manage data, or prevent the execution of scripts. The possible applications are very diverse.

General information[edit]

Unlike a plug-in, an add-on is not independent in its range of functions. The add-on expands the basic functions and provides a special feature for the system (client, browser, application). The program code of the basic system forms the basis for the add-on, which is logically linked to the code via interfaces (APIs) and software libraries. Add-on programs access these resources, while plug-ins provide their own resources and are independent.

Add-ons are customized using SDKs (Software Development Kit) for the particular system so they can be added later by download. Most add-ons are supplied by the creator of the basic system, such as the browser add-on for disabling Google Analytics, or various theme add-ons for Mozilla Firefox that change the look of this browser. Add-ons can also be offered by third-party vendors, independent developers or agencies, some of which are open systems and open-source software. They are often designed to handle special problems or tasks in the workflow.

How it works[edit]

Most add-ons are available for applications, browsers, and games. Add-ons are offered for download as part of the software, which it is intended to complement and can be installed with few clicks mostly free of charge. Add-ons can be roughly divided into two categories:  

  • Extensions: Single or multiple functions are added to an existing program. These add-ons are often referred to as browser extensions.
  • Individualization: Themes, templates, and personas change the look and design of the browser by optically adapting the graphical user interface.

For both versions, the add-on merely adds functions. It always depends on the basic program to supplement it. For this reason, the performance of the system is often impaired as the additional software is linked to the system at different points. Each add-on slows down the basic program to a certain degree (up to 10%) during a restart, because interfaces are accessed and system functions are used. Extensive individualizations of browsers are sometimes associated with a significant loss of performance.

In addition, some add-ons can transfer personal data or prevent basic software from transmitting data. On the one hand, data security and privacy can be established and expanded by add-ons, such as blocking scripts, advertising, and IP addresses. On the other hand, add-ons can also transfer data without the user noticing it. In principle, there is the risk of downloading malicious software with every download, especially with so-called software bundles.[1][2]

Before you add an add-on, you should first assess the provider’s legitimacy and trustworthiness of the source and the add-on to rule out any gaps in the security of the software and prevent attacks by malware. Even if such cases are rare, it is advisable to select add-ons based on specific requirements and thereby minimize potential risks. The manufacturers also offer mechanisms for verifying software, digital rights management, and encryption methods for data transmission. When downloading an add-on, it is advisable to check exactly where the additional software comes from, what it is doing and what data it transmits in which way.

Relevance to online marketing[edit]

Numerous add-ons and browser extensions are offered for online marketing, search engine optimization or web analysis. They simplify workflows and perform special tasks. One of the most famous add-ons is the Technical Firebug. This developer tool can examine various elements of a website and the underlying source code. Layouts, CSS markups, redirects and loading times can be analyzed and evaluated. Various add-ons are used to analyze backlinks, domain authorities or other KPIs. Scraper tools (Scraper for Chrome) can get data and export it into tables, for example. Numerous add-ons exist today including, redirects, canonical URLs, user agents, notes, and mind maps. Add-ons are so diverse that even special add-ons which manage add-ons are on the market and those are very handy.


  1. Researcher to demonstrate feature-rich malware that works as a browser extension Accessed on 09/06/2016
  2. Malwarebytes PUP Criteria Accessed on 09/06/2016

Web Links[edit]