Show HN: Underscore – Code with AI in the browser, zero setup required

I built Underscore a browser-based coding environment that runs entirely in the cloud. There’s no local setup, CLI, or Docker—open the site and start coding with AI assistance from any device.

Each project runs in its own persistent cloud container (Cloudflare) with common languages and tools preinstalled (Node.js, Python, Go, Rust, Bun, etc.). It’s built on top of opencode (https://opencode.ai ), an open-source AI coding agent.

Features:

Cloud containers with persistent storage

Access from any browser

75+ AI models (Claude Sonnet 4.5, GPT-5.2 Codex, DeepSeek R1, etc.)

Project templates (AI agents, serverless functions, web apps, APIs, E2E tests)

GitHub integration (clone repos, push changes back)

MCP directory with one-click setup for 20+ services (GitHub, Linear, AWS, Sentry, PostgreSQL, etc.)

Automatic public preview URLs for dev servers

Built-in terminal and file browser (code editor coming soon)

Status: Beta. Core workflows work, but there are rough edges.

I’d love feedback from HN on what’s useful, what’s missing, and where this fits (or doesn’t) in your workflow. Happy to answer questions about the architecture or AI integration.