StackBlitz WebContainers
StackBlitz WebContainers bring a full Node.js runtime directly into the browser, enabling instant, secure, and interactive development environments inside any web app. Developers can run native npm, pnpm, and yarn at speeds up to 10× faster than local, without needing external servers. The API lets you boot containers, mount files, install dependencies, and run dev servers entirely client-side. WebContainers support major frameworks, Wasm workloads, and modern browsers, making them ideal for tutorials, sandboxes, docs, and AI-driven developer tools. With isolated, disposable environments, teams can offer a seamless coding experience that feels native and eliminates backend overhead. The result is a powerful platform that transforms web apps into full-featured IDEs.
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Posit
Posit builds tools that help data scientists work more efficiently, collaborate seamlessly, and share insights securely across their organizations. Its Positron code editor provides the speed of an interactive console combined with the power to build, debug, and deploy data-science workflows in Python and R. Posit’s platform enables teams to scale open-source data science, offering enterprise-ready capabilities for publishing, sharing, and operationalizing applications. Companies rely on Posit’s secure infrastructure to host Shiny apps, dashboards, APIs, and analytical reports with confidence. Whether using open-source packages or cloud-based solutions, Posit supports reproducible, high-quality work at every stage of the data lifecycle. Trusted by millions of users—and more than half of the Fortune 100—Posit empowers professionals across industries to innovate with data.
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Devin Desktop
Devin Desktop (formerly Windsurf) is an AI-powered development environment that combines a full-featured IDE with advanced coding agents in a unified workspace. Formerly known as Windsurf, the platform enables developers to manage local and cloud-based AI agents, delegate tasks, review code, and ship software without leaving their editor. Developers can use multiple coding agents simultaneously to research, write, test, debug, and improve code while maintaining full visibility into every change. Devin Desktop includes features such as agent orchestration, shared workspaces, intelligent code completion, contextual code search, and integrated review tools. The platform supports a wide range of models, extensions, language servers, and MCP integrations, allowing teams to work with their preferred tools and workflows. Devin Desktop helps engineering teams accelerate software development, improve productivity, and manage AI-assisted coding at scale.
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JSFiddle
JSFiddle has the notion of panels (or tabs if you switch into the tabbed layout), there are 4 panels, 3 where you can enter code, and 1 to see the result: HTML - structure code, no need to add body doctype head, that's added automatically, CSS - styles. You can switch pre-pocessor to SCSS, JavaScript - behavior. There are many frameworks and code pre-processors you can use. Once you enter code, just hit "Run" in the top actions bar, and the fourth panel with results will appear. SFiddle allows you to switch the layout of the editor from the classic 2x2 grid to something that suits your needs. In addition to the grids mode it also has a tabbed mode. Grids are fully resizable. As an addition resizing the Results panel will tell you its width (handy for working on media queries).
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