Esri has geographic information system (GIS) development and deployment tools designed to meet your specific needs. With access to Esri development tools, you can choose the best application you build, helping you fulfil your users' current and future needs.
Esri UK offers tools, components, and software to help you:
By developing your own custom GIS applications, you can better integrate them with your existing technologies and workflows.
With ArcGIS, developers can work with a variety of APIs, standards and tools to create a robust GIS solution. ArcGIS provides a complete system for developing desktop, mobile and web applications as well as for interfacing with GIS web services.

Web Mapping APIs
ArcGIS API for JavaScript
ArcGIS API for Flex
ArcGIS API for Silverlight