# nucleus v0.1.1 - Table of Contents > Phoenix & React! ## Modules - [Nucleus](Nucleus.md): Nucleus keeps the contexts that define your domain and business logic. - [Nucleus.Mailer](Nucleus.Mailer.md) - [Nucleus.Repo](Nucleus.Repo.md) - [NucleusWeb](NucleusWeb.md): The entrypoint for defining your web interface, such as controllers, components, channels, and so on. - [NucleusWeb.CoreComponents](NucleusWeb.CoreComponents.md): Provides core UI components. - [NucleusWeb.Endpoint](NucleusWeb.Endpoint.md) - [NucleusWeb.ErrorHTML](NucleusWeb.ErrorHTML.md): This module is invoked by your endpoint in case of errors on HTML requests. - [NucleusWeb.ErrorJSON](NucleusWeb.ErrorJSON.md): This module is invoked by your endpoint in case of errors on JSON requests. - [NucleusWeb.Gettext](NucleusWeb.Gettext.md): A module providing Internationalization with a gettext-based API. - [NucleusWeb.Layouts](NucleusWeb.Layouts.md): This module holds layouts and related functionality used by your application. - [NucleusWeb.PageController](NucleusWeb.PageController.md) - [NucleusWeb.PageHTML](NucleusWeb.PageHTML.md): This module contains pages rendered by PageController. - [NucleusWeb.Router](NucleusWeb.Router.md) - [NucleusWeb.Telemetry](NucleusWeb.Telemetry.md)