Angular v21 debuts Signal Forms, stabilizes MCP server

Google’s Angular team has released Angular v21, the latest version of Google’s TypeScript-based web framework. This update introduces experimental Signal Forms, a reactive forms experience built on the Signals application state tracker, and launches a developer preview of Aria, a modern library for common user interface patterns that emphasizes accessibility. Angular v21 also brings Angular’s local Model Context Protocol (MCP) server to stable.

Angular v21 was unveiled November 20. Instructions for installing Angular can be found at angular.dev.

The Angular CLI MCP server, launched with the Angular v20.2 point release on August 20, has reached stable status in Angular v21. The MCP server has tools to give AI agents context about modern Angular and the developer’s application, and promises to help users become better developers, according to the Angular team. The MCP server can be used to gain general context, find up-to-date information, update an application, and teach Angular, the team said. The MCP server follows the May 30 Angular v20 release that supported AI development through the introduction of an llms.tx file for large language models (LLMs).

Signal Forms, an experimental library for managing forms state with signals, provides a new scalable, composable, and reactive forms experience built on Signals. With Signal Forms, the Form model is defined by a signal that automatically syncs with the form fields bound to it. This allows for an ergonomic developer experience with full type safety for accessing form fields. Centralized schema-based validation logic is built-in. The Angular team added that, with signals driving modern Angular state management, zone.js no longer is needed for change detection. Zoneless change detection, introduced experimentally in Angular v18, progressed through Developer Preview in Angular v20 and reached stability in Angular v20.2. Angular traditionally used zone.js to track changes in applications, but zone.js has performance drawbacks, the Angular team said. Zoneless change detection offers benefits including better core web vitals, native async-await, ecosystem compatibility, reduced bundle size, easier debugging, and better control, the team said.

Also featured in Angular v21 is a developer preview of Angular Aria, a library for common UI patterns. The library is a collection of headless, accessible directives that implement common WAI-ARIA patterns. These directives handle keyboard interactions, ARIA attributes, focus management, and screen reader support, according to the Angular team. Developers just have to provide the HTML structure, business logic, and CSS styling. To start, developers have access to eight UI patterns encompassing 13 components that are completely un-styled and can be customized. The patterns include Accordion, Combobox, Grid, Listbox, Menu, Tabs, Toolbar, and Tree. Elsewhere in Angular v21, the Vitest testing framework has been made the default test runner and has been promoted to stable status.