The best open source alternative to Codex is opencode. If that doesn't suit you, our users have ranked more than 100 alternatives to Codex and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Codex are Void, Mellum, Emdash and TabbyML.
Terminal-based AI coding assistant featuring a themed native UI, automatic LSP integration, multi-agent sessions, 75+ supported LLMs, local and cloud model options, shareable debugging links, open source licensing, and session sharing for collaborative coding workflows.
United States
The open source AI code editor. Write code with the best AI tools, use any model, and retain full control over your data.
Mellum-4b-base is JetBrains' first open-source large language model (LLM) optimized for code-related tasks.
Czechia
EU
Emdash is a provider-agnostic desktop app that lets you run multiple coding agents in parallel, each isolated in its own git worktree, either locally or over SSH on a remote machine. We call it an Agentic Development Environment (ADE).
United States
Tabby is an open-source, self-hosted AI coding assistant. With Tabby, every team can set up its own LLM-powered code completion server with ease.
United States
Pi aka Pi.dev is a minimal terminal coding harness. Adapt pi to your workflows, not the other way around, without having to fork and modify pi internals.
Australia
A minimalist, terminal-native coding agent. A single native C binary that uses a few MBs of RAM. Local models are first-class via llama.cpp and Ollama; also OpenAI, Anthropic, OpenRouter, and Codex.
Ukraine
Terminal-native open-source AI coding assistant for Mac, Windows, Linux, and BSD, featuring cross-session memory, reading and writing code, Git management, command execution, built-in MiMo Auto for zero configuration start, and integration with mainstream LLM provider APIs.
China
Autonomous coding agent right in your IDE, capable of creating/editing files, executing commands, using the browser, and more with your permission every step of the way.
United States
Open source AI coding assistant for planning, building, and fixing code. We frequently merge features from open-source projects like Roo Code and Cline, while building our own vision.
United States
Visual AI programming platform with a graphical interface for creating, editing, and debugging LLM agent workflows, supporting real-time collaboration, YAML-based version control, open-source TypeScript library integration, and scalable deployment in production environments.
United States
A multi-platform, AI-augmented coding companion ensuring secure development with unit test creation.
