21st Fund

21st Fund (also known as 1Code by 21st) is an open-source client application that provides a calm, visual interface for Claude Code. Backed by Y Combinator, it enables developers to run multiple AI-assisted coding sessions in parallel, track progress visually, and manage their development workflow more effectively. The platform offers a keyboard-first UI designed for productivity, allowing users to work on multiple features simultaneously using parallel agents running locally, in worktrees, or in the background.

Getting started with 21st Fund is straightforward and takes just a few steps to begin AI-assisted coding.

1. Sign In with Anthropic - Connect your Anthropic account to the platform. The service uses your existing Claude Pro or Max subscription for AI capabilities.

2. Choose Your Client - Download the macOS desktop application for local use, or access the web and mobile apps if you subscribe to the Pro plan.

3. Create a New Session - Launch a new coding session and specify your project directory. You can run multiple sessions in parallel.

4. Run Agents Anywhere - Launch AI agents from the web interface or the macOS app. Both options provide the same powerful Claude Code features.

5. Ship from the UI - Open pull requests and merge changes directly within the interface, eliminating context switching between tools.

Parallel Agents - Work on multiple features at once by running agents locally, in worktrees, or in the background for maximum productivity.

Full Claude Code Power - Access all Claude Code features including plan mode, skills, message editing, and more through an intuitive interface.

Keyboard-First UI - Navigate, create, and manage your workflow using hotkeys for every action without touching your mouse.

Plugin System & Marketplace - Extend functionality with plugins and MCP authentication through the built-in marketplace.

Live Browser Previews - View live browser previews of your development branches directly within the interface (Pro plan).

Automated Workflows - Set up automations for PR reviews, Linear tasks, and CI/CD fixes to streamline your development process.

Multi-Platform Access - Use the local macOS desktop client, web app, or mobile app to run background agents from anywhere.

#1 Full-Stack Development - Run parallel agents to work on frontend and backend features simultaneously, significantly speeding up development cycles.

#2 Code Review Automation - Set up automated PR reviews to catch issues early and maintain code quality across your team.

#3 Bug Fixing & Debugging - Leverage Claude Code's AI capabilities to quickly identify and fix bugs while maintaining context across multiple sessions.

#4 Feature Implementation - Work on multiple features in parallel using separate agents, each maintaining its own context and progress.

#5 CI/CD Pipeline Management - Automate fixes for failed CI/CD pipelines, reducing time spent on build and deployment issues.

#6 Mobile Development Workflow - Run background agents from your phone to monitor long-running tasks or kick off new development sessions on the go.

Is 21st Fund the same as 1Code? Yes, 21st Fund (21st.fund) redirects to 1Code, which is the primary product developed by 21st.dev. Both names refer to the same Claude Code client application.

Do I need a Claude subscription to use 21st Fund? Yes, you need a Claude Pro or Max subscription from Anthropic. 21st Fund connects to your Anthropic account to use Claude's AI capabilities.

Is my code sent to 21st.dev servers? No, your code stays local when using the desktop client. The platform runs Claude Code locally on your machine.

What operating systems are supported? Currently, the desktop client is available for macOS. Web and mobile access is available for Pro plan subscribers.

Is 21st Fund affiliated with Anthropic? No, 21st Fund is developed by 21st.dev as an independent open-source project. It is backed by Y Combinator but is not officially affiliated with Anthropic.