Lifo vs WebContainers: Open-Source vs Proprietary
If you're building a product that runs code in the browser — an AI coding assistant, an interactive tutorial platform, a browser IDE — you've probably looked at WebContainers. It's the technology behind StackBlitz, Bolt.new, and several other developer tools. It runs Node.js in the browser. It works. It's impressive.
But if you're looking for a WebContainers alternative, there's a reason you're searching. Maybe it's the licensing — WebContainers requires a commercial license for production use in for-profit settings. Maybe it's the proprietary API that you can't fork, self-host, or modify. Maybe you want something fully open-source that you actually own.
Lifo is that alternative. It's a browser-native operating system, MIT-licensed, that maps Web APIs to POSIX interfaces. No proprietary licensing. No commercial restrictions. No API request limits. Your code, your product, your terms.
This post breaks down how the two compare — technically, commercially, and philosophically.
The Licensing Problem
This is the elephant in the room, so let's start here.
WebContainers is proprietary software owned by StackBlitz. The WebContainer API is free for open-source projects and prototypes, but production usage in a commercial, for-profit setting requires a paid license. If you're using the API to serve your customers, prospective customers, or employees, you need a commercial agreement with StackBlitz. Enterprise plans include self-hosted options, private NPM registry support, and SAML SSO — but pricing isn't public. You contact sales.
The specific constraints: free-tier commercial plans are capped at 500 sessions per month. Beyond 10,000 API requests per month, additional charges apply. For a startup embedding code execution into its product, these limits can become a bottleneck fast.
Lifo is MIT-licensed. That's the most permissive open-source license there is. You can use it commercially, modify it, embed it in proprietary products, fork it, redistribute it — no license fees, no session caps, no sales calls. The entire codebase is on GitHub.
For indie developers, startups, and open-source projects, this isn't a minor difference. It's the difference between building on someone else's proprietary platform and owning your stack.
Architecture Comparison
Both Lifo and WebContainers run code in the browser. But they take different approaches to get there.
WebContainers virtualizes a Linux-like environment inside the browser using a custom runtime. It runs a full Node.js server, supports npm package installation at runtime, and provides a virtual filesystem. Under the hood, it uses Service Workers to intercept network requests and simulate a server environment. StackBlitz spent seven years building this technology.
Lifo maps POSIX/Unix interfaces directly to Web APIs. It provides a bash-like shell, a virtual filesystem backed by IndexedDB, 60+ Unix commands implemented in JavaScript, and WebAssembly package support. Rather than simulating a server, Lifo gives you an operating system abstraction built natively on browser primitives.
The practical difference: WebContainers is optimized for running Node.js and its ecosystem. Lifo is optimized for providing a general-purpose OS environment — shell, filesystem, pipes, processes — that works with JavaScript, TypeScript, and any language compilable to WebAssembly.
Feature-by-Feature Comparison
| Feature | Lifo | WebContainers |
|---|---|---|
| License | MIT (fully open-source) | Proprietary (commercial license required) |
| Node.js support | Compatibility shims (fs, path, process) | Full Node.js runtime |
| npm install | 60+ built-in packages, Wasm packages via pkg | Full npm with runtime installation |
| Shell | Bash-like (pipes, redirects, globs, history) | jsh (basic shell) |
| Filesystem | IndexedDB-backed, persistent across sessions | In-memory virtual FS |
| Persistence | Yes — files survive refresh/restart | No — resets on page reload |
| Unix commands | 60+ (ls, grep, sed, awk, curl, tar, git...) | Limited to Node.js ecosystem |
| WebAssembly packages | Yes (ffmpeg, python, sqlite...) | No native Wasm package system |
| Multi-language | JS + any Wasm-compiled language | Primarily Node.js/JS ecosystem |
| Commercial use | Free, unlimited | License required, session caps |
| Self-hostable | N/A (runs client-side, no server) | Enterprise plan required |
| API request limits | None | 10,000/month free, then paid |
| Session limits | Unlimited (browser tab lifetime) | 500/month on commercial free tier |
| Offline support | Yes | Limited (needs initial load) |
| Fork & modify | Yes (MIT) | No (proprietary) |
| Backed by | Open-source community | StackBlitz ($135M+ raised, $700M valuation) |
Where WebContainers Wins
WebContainers is a mature, well-funded technology. It deserves credit for pioneering browser-based Node.js execution.
Full Node.js compatibility. WebContainers runs an actual Node.js server in the browser. That means npm install works the way you expect — it resolves dependencies, downloads packages, and installs them at runtime. If your product needs users to install arbitrary npm packages and run complex Node.js applications, WebContainers has deeper compatibility here.
Battle-tested at scale. Bolt.new hit $40M ARR in six months running on WebContainers. StackBlitz has been building this technology for seven years. It powers production products used by millions. If you're risk-averse and need proven technology, WebContainers has the track record.
Framework support. WebContainers can run full-stack frameworks like Next.js, Vite, Express, and others with hot reload working out of the box. The Node.js runtime is complete enough to handle complex dev server setups.
Enterprise features. Self-hosted deployment, private NPM registries, SAML SSO, priority support. For large organizations with compliance requirements, StackBlitz has the enterprise sales motion figured out.
Where Lifo Wins
Lifo takes a different bet: that open-source, general-purpose browser OS capabilities will serve more use cases than a proprietary Node.js runtime.
Truly open-source. This is the fundamental difference. With Lifo, you can read every line of code, fork the project, modify it for your needs, and ship it in your product without asking anyone's permission. No license negotiation, no vendor lock-in, no surprise pricing changes. With WebContainers, you're building on proprietary technology controlled by a company optimizing for its own revenue ($40M ARR via Bolt.new).
No commercial restrictions. Build a competitor to Bolt.new using Lifo? Go ahead. Build a paid coding platform? No license needed. Embed it in a product serving 100,000 users? Zero cost. With WebContainers, every one of these scenarios requires a commercial agreement.
Persistent filesystem. Lifo's IndexedDB-backed filesystem survives page refreshes and browser restarts. WebContainers uses an in-memory filesystem that resets when the page reloads. For use cases like educational platforms (where students need to save progress) or browser IDEs (where developers expect files to persist), this matters.
Full shell experience. Lifo provides a bash-like shell with pipes, redirects, glob expansion, environment variables, command history, and tab completion. WebContainers ships jsh, a more basic shell. If your product needs a real terminal experience — think coding tutorials, interactive documentation, or dev environments — Lifo's shell is significantly more capable.
Multi-language via WebAssembly. Lifo's package system lets you install Python, SQLite, ffmpeg, and other tools compiled to WebAssembly. WebContainers is fundamentally a Node.js runtime — if your use case involves non-JavaScript languages, you're working against the grain.
Zero vendor risk. StackBlitz is a $700M-valued VC-backed company. That's great for them, but it means their incentives include maximizing revenue, not keeping things free for your use case. Licensing terms can change. Pricing can increase. APIs can be deprecated. With MIT-licensed software, the code is yours regardless of what happens to the company that created it.
The Licensing Deep Dive
Because licensing is often the deciding factor, let's be specific about what each allows.
What You Can Do With Lifo (MIT License)
- Use it in any commercial product — free
- Modify the source code for your needs
- Bundle it in proprietary software
- Redistribute it (with or without modifications)
- Use it for unlimited users, sessions, and API calls
- Fork it and build your own product on top of it
- Never talk to a sales team
What You Can Do With WebContainers
- Use it for open-source projects — free
- Use it for prototypes and POCs — free
- Use it commercially with up to 500 sessions/month — free (with StackBlitz plan)
- Use it commercially beyond 500 sessions — paid license required
- Use it beyond 10,000 API requests/month — additional charges
- Self-host it — Enterprise plan required (contact sales)
- Fork or modify the core runtime — not permitted
- Use it without depending on StackBlitz — not possible
For a solo developer building a side project, WebContainers' free tier is fine. For a startup embedding code execution as a core feature, the licensing constraints become a strategic dependency.
Real-World Use Cases
AI Coding Assistants
Both work here, but the licensing economics diverge quickly. An AI assistant that generates and runs code for every user interaction can hit thousands of sandbox sessions per day. With WebContainers, that means a commercial license and per-session costs. With Lifo, it's free regardless of scale because execution happens on the user's device.
Interactive Documentation
Lifo's persistent filesystem is a significant advantage. A documentation site with interactive examples can let users modify code, save their changes, and come back later. WebContainers resets on every page load, so users lose their work.
Educational Platforms
Coding bootcamps and tutorial sites need two things: low cost at scale (thousands of simultaneous students) and progress persistence (students should be able to pick up where they left off). Lifo delivers both out of the box. WebContainers requires a commercial license for scale and doesn't persist filesystem state.
Browser IDEs and Playgrounds
If you're building a coding playground that needs full npm ecosystem support and framework hot-reload, WebContainers has an edge. If you're building a playground that needs a real shell experience, file persistence, and multi-language support via Wasm, Lifo is the better foundation.
Hackathon and Contest Platforms
Platforms running coding contests need sandboxed execution for thousands of concurrent users. The per-session licensing model of WebContainers makes this expensive. Lifo's MIT license and client-side execution make it essentially free.
Migration Guide: WebContainers to Lifo
If you're currently using the WebContainer API and evaluating a switch, here's the practical mapping:
Filesystem operations map closely. WebContainers uses webcontainerInstance.fs.readFile() / writeFile(). Lifo uses sandbox.fs.readFile() / writeFile(). The API shape is similar.
Running commands is comparable. WebContainers: webcontainerInstance.spawn('node', ['script.js']). Lifo: sandbox.exec('node script.js').
Package installation differs. WebContainers runs npm install with full dependency resolution. Lifo uses built-in packages and Wasm packages via pkg install. If your product depends on users installing arbitrary npm packages at runtime, verify that the packages you need are available.
Server-side features are where the gap exists. If you use WebContainers to run an Express or Next.js dev server in the browser, Lifo may not cover all those cases today. For script execution and shell-based workflows, the migration is straightforward.
The Strategic Question
The choice between Lifo and WebContainers isn't just technical — it's strategic.
Building on WebContainers means building on StackBlitz's proprietary platform. You benefit from their seven years of engineering investment. You also inherit a dependency on their licensing, pricing, and product roadmap. If StackBlitz decides to raise prices, change license terms, or sunset the API, your product is exposed.
Building on Lifo means building on open-source infrastructure. You trade some Node.js ecosystem depth for full ownership of your stack. You can fork the code, contribute improvements upstream, and never worry about licensing changes. Your business is not coupled to another company's revenue model.
For most startups and developer tools companies, ownership and control over core infrastructure is more valuable than a slightly deeper Node.js runtime. Especially when the technology is free.
Getting Started
Try Lifo — open it in your browser. No signup, no API key, no install.
# Or add it to your project:
npm install @lifo-sh/core
import { Sandbox } from '@lifo-sh/core';
const sandbox = await Sandbox.create();
await sandbox.exec('echo "No license required"');
const files = await sandbox.fs.readdir('/home/user');
console.log(files);
Lifo is MIT-licensed and open-source on GitHub.
Frequently Asked Questions
Is Lifo a drop-in replacement for WebContainers?
Not exactly. The APIs are different, and WebContainers has deeper Node.js runtime compatibility (full npm install, dev server support). But for the most common use cases — running scripts, file operations, shell commands, and AI agent sandboxing — Lifo covers the same ground without the licensing constraints. Migration typically involves adapting API calls rather than rearchitecting.
Can I use WebContainers for free in a commercial product?
It depends on scale. Commercial StackBlitz plans include 500 WebContainer sessions per month. Beyond that, or beyond 10,000 API requests per month, you need a paid license. Prototypes and open-source projects are free. Check StackBlitz's commercial use page for current terms.
Why does licensing matter if WebContainers works well?
Because your product's cost structure and strategic independence depend on it. Today's free tier can become tomorrow's paid requirement. Proprietary dependencies give the vendor leverage over your business. With MIT-licensed infrastructure, you eliminate that risk entirely.
Does Lifo support running Next.js or Vite dev servers?
Lifo supports running Node.js scripts with compatibility shims for core modules (fs, path, process). Full dev server support (with hot module replacement and the complete webpack/Vite pipeline) is an area where WebContainers has a current advantage. Lifo's focus is on shell-based workflows, script execution, and general-purpose OS capabilities rather than replicating a full Node.js server environment.
Which should I choose if I'm building a Bolt.new competitor?
Lifo. Building a competitor to a StackBlitz product on StackBlitz's proprietary technology creates an obvious conflict of interest. StackBlitz controls the runtime, the licensing terms, and the pricing. With Lifo, you own your entire stack — and you don't need to ask your competitor for permission to ship.