StackBlitz

Yes — StackBlitz invented WebContainers, a WebAssembly-based OS that runs a real Node.js process inside a browser tab (Chromium-based browsers only). This is fundamentally different from CodeSandbox's older approach (running on a remote VM). WebContainers means no network round-trip for npm install, instant feedback, and the ability to work offline once a project is open. It also means StackBlitz can't run native modules that require C++ bindings, which CodeSandbox can.

Yes — StackBlitz is free for public projects with reasonable compute limits. The Teams plan ($90/user/year) adds unlimited private projects, more CPU and RAM, team workspaces, and SOC 2 compliance. Pro individual plans ($15/month) sit between. The free tier is generous enough for most personal use, framework reproductions, and small open-source projects.

StackBlitz uses WebContainers (Node.js in the browser, faster startup, offline-capable, no native modules). CodeSandbox uses cloud VMs (slower startup but supports any Node.js workload including native modules, Python, databases). StackBlitz is preferred by framework reproduction repros (Vite, Vue, Svelte all default to it). CodeSandbox is better for full-stack apps with databases or non-Node services. Both have free tiers.

Yes — because WebContainers run Node.js in the browser, once a StackBlitz project is open the dev server, npm scripts, and HMR all work offline. This is the biggest practical advantage over CodeSandbox. The initial git-clone and npm-install require network, but iterative editing does not. The PWA installs cleanly on Chromium browsers.

StackBlitz is the default reproduction repro tool of the Vue, Vite, Svelte, Angular, Astro, and TanStack ecosystems — bug reports in those repos request StackBlitz links. Bolt.new (also by StackBlitz) became one of the fastest-growing AI coding tools of 2024 by combining WebContainers with Claude/GPT-4. The Bolt success has positioned StackBlitz as foundational infrastructure for AI-augmented full-stack tooling.