1Code

Open-source UI to run multiple Claude Code agents in parallel

1Code is an open-source client for running multiple Claude Code (and Codex) agents concurrently, available as a native macOS app with local Git worktree isolation and as a web app with remote sandboxes and live browser previews. It targets developers who want to parallelize AI coding tasks across features or code segments without conflicts. Built by 21st.dev (YC-backed); self-hostable from source, with a paid subscription for pre-built releases and background agent automations.

Install & run

from sourcegit clone https://github.com/21st-dev/1code && cd 1code && bun install && bun run dev

Source & docs

Repository Docs

At a glance

Company: 21st.dev
Pricing: freemium
API available: No
Self-hostable: Yes
Launched: 2026-01
Last verified: 2026-08-22

Capabilities

parallel-agentsgit-worktreeslive-previewmulti-file-editmcp-support

Alternatives

Cursor — VS Code fork with deep AI coding and multi-file editing

For AI agents: machine-readable markdown version of this page at /tools/1code-2.md, or send Accept: text/markdown.