OpenCode

OpenAI coding agent for app, editor, terminal, and cloud work

Codex is OpenAI's coding agent for software development across the Codex app, editor, terminal, and cloud tasks. It helps write, review, debug, refactor, and automate code, with ChatGPT plan access for managed surfaces and API-key usage for CLI, SDK, and IDE workflows. The open-source CLI and SDK support local repository work, while cloud features add GitHub review, Slack/Linear integrations, worktrees, skills, MCP, and automations.

Open-source extensible AI agent by Block

Autonomous coding agent from Block (Square) that works with any LLM through MCP-first extensibility. Apache 2.0 licensed with 47K+ GitHub stars and a Linux Foundation AAIF founding project. Designed for terminal-based workflows with deep tool integration, making it a strong open-source option for developers who want agent-assisted coding without vendor lock-in.

LSP-powered semantic coding agent via MCP

Serena is a free, open-source coding agent toolkit that provides IDE-like semantic code retrieval and editing capabilities to any LLM via the Model Context Protocol (MCP). Built on Language Server Protocol (LSP) integration, it enables symbol-level navigation, cross-file refactoring, and relational code understanding across Python, TypeScript, Go, Rust, Java, PHP, and more — without requiring file-level reads or text-based search.

xAI's terminal coding agent with parallel subagents and worktree-aware automation

Grok Build is xAI's terminal-first coding agent for planning, editing, testing, and reviewing code from a local CLI. The early beta exposes subagent controls, worktree mode, headless JSON output, best-of-N parallel attempts, sandbox profiles, and experimental memory. It fits developers comparing Claude Code, Codex, and Gemini CLI for local agentic workflows with deeper parallel execution.

Fast, native terminal emulator

GPU-accelerated terminal emulator written in Zig by Mitchell Hashimoto (HashiCorp co-founder). Native UI rendering on macOS and Linux. Supports ligatures, true color, Kitty graphics protocol, and splits/tabs. Configurable via a simple key-value file with sensible defaults. Open-source with 20K+ GitHub stars and a focus on correctness, speed, and minimal resource usage. Growing as a modern alternative to iTerm2, Alacritty, and WezTerm.

Anthropic's agentic coding CLI

Anthropic's agentic CLI coding tool that delegates complex tasks to Claude directly from the terminal. Understands entire codebases via automatic context gathering, edits multiple files, runs shell commands, and manages Git workflows autonomously. Supports CLAUDE.md for persistent project instructions, integrates with VS Code and JetBrains, and uses Claude Opus/Sonnet with extended thinking for complex architectural decisions. Built for terminal-first developers.

The AI-first code editor

AI-first code editor built as a VS Code fork that deeply integrates LLMs into every part of the development workflow. Features Tab autocomplete with multi-line predictions, Cmd+K inline editing, AI chat with full codebase awareness, and Agent mode for autonomous multi-file edits with terminal execution. Supports GPT-4, Claude, and more with automatic context from project files and docs. Includes privacy mode for SOC 2 compliance. The leading AI-native IDE with 100K+ paying users.

Community fork of Codex CLI with Auto Drive, browser integration, and multi-agents

Open-source terminal coding agent (npm `@just-every/code`) — a substantive community fork of OpenAI's Codex CLI adding Auto Drive orchestration, browser/CDP integration, multi-agent commands, theming, and Auto Review, while staying upstream-compatible.

Community-built, local-first terminal coding agent — bring your own model

An open-source terminal coding agent from the non-profit Nano Collective. Runs agentic coding on the model of your choice — local via Ollama or any OpenAI-compatible API — with no paid tiers and nothing gated behind a vendor.