Fragments by E2B offers developers a way to rapidly prototype and build web applications and UI components using AI. This open-source tool translates natural language prompts into functional code, streamlining the development process for various projects.
AI Sandbox for Full-Stack App Prototyping
Fragments simplifies web application creation by allowing users to describe their desired app or component in plain English. The AI then generates the corresponding code, which developers can preview in the browser and deploy. It’s built on a solid tech stack including Next.js 14, shadcn/ui, and TailwindCSS, and integrates with the Vercel AI SDK.
Frontend Developers, Startup Founders, and Hackathon Teams
This tool serves several user groups, including developers, AI enthusiasts, ML engineers, AI product teams, and students. Specific use cases range from rapid prototyping of web applications and generating UI components to building functional apps like login pages, budget planners, or weather apps. It also supports more advanced applications, such as automating business processes with AI agents and data analysis.
E2B Sandboxed Runtime, Supports Claude and GPT-4
A key differentiator for Fragments is its reliance on the E2B SDK, which provides secure, isolated sandbox environments for executing AI-generated code. These environments are Linux virtual machines built on Firecracker microVMs, offering kernel-level isolation for enhanced security. Fragments is also LLM-agnostic, supporting a wide array of large language models from providers like OpenAI (GPT-4o, GPT-4), Anthropic (Claude 3.5 Sonnet), Google AI (Gemini), Mistral, Groq, Fireworks, Together AI, and Ollama. It can handle multiple programming languages and frameworks, including Python, Next.js, Vue.js, Streamlit, and Gradio, and allows for package installation via npm and pip.
Free Tier, $0.05/Execution on Pro Plan
While Fragments itself is free and open-source, its functionality depends on the E2B platform, which operates on a freemium model with usage-based pricing. Users need an E2B API key and an LLM Provider API key for self-hosting.
| Plan | Price | Key Details |
|---|---|---|
| Hobby (Free) | Free | One-time $100 usage credits, community support, up to 1-hour sandbox session, up to 20 concurrent sandboxes |
| Pro | $150/month (base) | Customizable Sandbox CPU & RAM, up to 24-hour session, 100-1,100 concurrent sandboxes |
| Enterprise | Custom | Custom pricing for higher limits and specialized features |
Billing for E2B is postpaid, charged at the start of the month for the previous month’s usage.
Limited to Web Apps, Sandbox Size Constraints
Despite its capabilities, AI generation isn’t always perfect on the first try. Users may need to iterate or manually adjust the generated code to fix issues like overflowing text or missing UI elements. While Fragments is free, the underlying E2B platform incurs usage-based costs once the initial free credits are exhausted. Open issues on the E2B platform include problems with Python HTML chart output, memory pressure with large build contexts in the JS SDK, and "429 WAIT signal lost" errors in Python and JS SDKs. There’s also an ongoing issue regarding unstable AI responses affecting reproducibility.
Fastest Path from Prompt to Running App
Fragments excels in the secure execution of untrusted AI-generated code, thanks to E2B’s Firecracker microVM-based kernel-level isolation, which offers a stronger security boundary than typical container-based solutions. It provides a streamlined workflow for rapid prototyping and deployment of web applications directly from natural language prompts, often proving faster and more flexible than alternatives like Bolt.new or v0.dev. Its open-source nature promotes transparency and customization, allowing for custom personas and integration with a wide array of LLMs, making it more adaptable than some bundled code interpreters.