Bolt.new is StackBlitz's answer to the AI app builder category, and its distinguishing feature is running entirely in the browser through WebContainers, StackBlitz's technology for running a full Node.js environment client-side without a remote server. A prompt produces a working app with an instant live preview, since the code is actually executing in the browser tab rather than waiting on a backend to spin up.
It uses Claude as its primary model for code generation and covers both web and mobile app scaffolding, handling routing, state, and basic backend logic from a natural-language description. Because everything runs in WebContainers, forking, editing, and redeploying a generated project stays fast, without the cold-start delay that comes from provisioning real cloud infrastructure for every iteration.
It competes directly with Lovable and v0 in the crowded AI app builder space, with StackBlitz's in-browser execution model as its main technical differentiator rather than a difference in what kinds of apps it can build.