OpenAI Codex CLI is an open-source (Apache 2.0), Rust-built terminal coding agent. It has over 72,000 GitHub stars. It pairs GPT-5.4’s 272K default context window, which you can push to 1M tokens, with OS-level sandboxing. That sandbox runs on Apple Seatbelt on macOS and Landlock plus seccomp on Linux. Here is the key point: Codex CLI is the only major AI coding agent that enforces security at the kernel level, not through application-layer hooks. With codex exec for CI pipelines, MCP client and server support, and a GitHub Action for PR review, it is the most infrastructure-ready rival to Claude Code in 2026.

You can unify access to Ollama, vLLM, cloud providers like OpenAI, Anthropic, and Google, plus custom model servers behind one OpenAI-compatible endpoint using LiteLLM Proxy . LiteLLM is a reverse proxy. It maps the standard /v1/chat/completions request to each provider’s native API. From one YAML file it handles auth, model routing, load balancing, fallbacks, rate limits, and spend tracking. Your app calls one endpoint with one key, and LiteLLM picks the right backend. You can swap models, add providers, or run A/B tests without touching app code.