Best GitHub Copilot CLI Alternatives

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.

Amp Frontier Corporation's multi-model coding agent for terminal, web, and IDE-connected workflows. It uses GPT-5.6, Claude Fable 5, and fast models across low, medium, high, and ultra modes, with subagents, an Oracle second-opinion model, shared threads, remote orbs, MCP, and plugins. Pricing combines a daily free credit grant, $20/$200 monthly subscriptions, and optional pay-as-you-go credits.

Open-source terminal-based AI coding agent built in Go by the SST team, with a rich TUI (Bubble Tea) supporting 75+ model providers including OpenAI, Anthropic, Gemini, Bedrock, Groq, and OpenRouter. Features vim-like editing, persistent SQLite sessions, and LSP integration for 40+ languages. Fully free with no vendor lock-in, it has rapidly grown to 95k+ GitHub stars.