AddOn

An add-on is a software component that extends the capabilities of a larger application without altering its core code. Add-ons are typically packaged as separate modules that integrate with the host via a defined API, enabling users to customize or enhance functionality. They may add features, modify behavior, or provide integration with external services.

Add-ons are common across many computing environments. In web browsers, extensions or add-ons can block ads, manage passwords, translate pages, or change the user interface. In content management systems such as WordPress, plugins serve a similar purpose by adding tools for search optimization, analytics, or e-commerce. In multimedia and design software, plugins add effects, formats, or automation, while in games, add-ons or mods modify gameplay or visuals. The exact terminology varies by ecosystem, with extensions, plugins, add-ins, and modules sometimes used interchangeably.

Distribution and installation typically occur through official marketplaces or repositories maintained by the host project or third-party developers. Add-ons include metadata, permissions, and sometimes a manifest describing how they integrate with the host. Security and safety considerations are important, since add-ons run with varying levels of access to data and system resources. Users should obtain add-ons from trusted sources and review requested permissions; developers should follow best practices for code signing, sandboxing, and updates.

Lifecycle and governance vary by platform. Add-ons may be officially supported for a defined period, requiring compatibility updates after host software releases. Community-driven ecosystems often rely on user ratings, open standards, and documented APIs to foster interoperability and reduce fragmentation.