Claude Code & Codex: Full Install and Setup Guide (2026)

Claude Code and Codex are the two tools I can't get through a coding day without now. People keep asking how to install and set them up, so here's everything I learned the hard way. Follow along and you'll be running in about ten minutes.

What are these two, exactly?

Claude Code is Anthropic's command-line coding assistant. It runs right in your terminal, reads your whole project, edits code, runs commands. Codex is OpenAI's take on the same idea. I use both, depending on the job.

Honestly, the first time I tried Claude Code I was skeptical. Thought it was just another fancy autocomplete. Then it refactored something spanning seven or eight files in one shot. That's when it clicked.

Installing Claude Code

Prerequisite: Node.js 18+.

npm install -g @anthropic-ai/claude-code

Then in your project directory:

claude

First run asks you to log in — either an Anthropic account or an API key. If your network is flaky, API key plus a base URL is more reliable:

export ANTHROPIC_API_KEY="your-key"
export ANTHROPIC_BASE_URL="your-endpoint"

Put these in ~/.bashrc or ~/.zshrc so you don't redo it every time. I got burned by this once — didn't persist it, closed the terminal, login gone, thought the tool was broken.

Installing Codex

Similar deal:

npm install -g @openai/codex
export OPENAI_API_KEY="your-key"

Then run codex.

A few things that doubled my output

Don't treat it like a search box. Give it context — project background, constraints, the style you want. The more specific, the better the result.

Before big changes, tell it to read the code first. A simple "read the src directory and understand the structure first" saves you from bad edits.

Let it run its own tests. It fixes its own errors across a few rounds, way faster than manual debugging.

Network issues

Direct calls to official APIs time out a lot in some regions. Use a relay service or a proxy. Claude Code respects ANTHROPIC_BASE_URL; Codex takes OPENAI_BASE_URL. That's usually all it takes.

Also worth checking out newer agents like Manus if you want more autonomous workflows. Come share your setup on the community — people trade tricks on these tools every day.

Browse more AI workflows in AI Playbook, or head back to the PromptCube homepage.