Understand before changing
Read the project, name the goal and give Codex the context it needs.
Opening your learning workspace… Read the complete course
An independent OpenAI Codex guide
Get to work
with Codex.
A hands-on guide to OpenAI Codex, from your first task to skills and connected tools. Learn in the desktop app, work with real files, and check what you build.
10 modules60 practical lessons7 practice projects
App first. CLI and IDE differences explained. Browse this guide on GitHub ↗
A small task. A complete workflow.
Your taskFix the search.
Fix the search.
Keep the notes.
Make search ignore case and surrounding spaces. Preserve every note and its order.
AGENTS.md4 sample notes
Read the project before editing.
notes.cjs1 focused change
function searchNotes(notes, query) {− return notes.filter(note => note.title.includes(query));+ const needle = query.trim().toLowerCase();+ return notes.filter(note => note.title.toLowerCase().includes(needle)); }Normalize the query. Keep the original objects and order.
Reference resultSmall change.
Small change.
Six checks passed.
node --test checks.cjs6tests
6passed
0failed
Blank queries, case, spaces, substrings, absent terms, and preserved data.
From a clear brief to a change you can verify. Static preview; no commands run.
How you’ll learnA clear brief.
A clear brief.
A result you can check.
Learning the tool is the beginning. The useful habit is knowing what to ask, what changed, and whether it worked.
Make one useful change
Work through a bounded exercise. Open real files and inspect the difference.
Check it for yourself
Run the checks, compare the reference answer and test your understanding.
The curriculum
Build your way through.
Three levels, one continuous path.
18h 39m of practice, estimated.
Level 1
Foundations
Get comfortable with the app, give useful context and make your first changes.
Module 01 Commands and your first session
Start in the right place, discover real commands and turn repeated requests into usable workflows.
Module 02 Project guidance and memory
Keep durable instructions explicit and understand what local Codex memories can and cannot preserve.
Module 03 Checkpoints, recovery and Git
Separate conversation history from file state, inspect changes and practise bounded recovery.
Module 04 Working from the command line
Use the interactive CLI and bounded scripted runs, with deliberate permissions and verifiable outputs.
Level 2
Connected workflows
Build reusable skills, connect tools and delegate with clear boundaries.
Module 05 Skills
Build reusable Codex workflows, control their activation and verify how they behave in delegated work.
Module 06 MCP
Connect Codex to the right tools, separate configuration from authorization and recognize product-specific integration boundaries.
Module 07 Subagents
Delegate bounded work, configure focused roles and combine evidence without confusing threads, permissions or filesystem isolation.
- Delegate independent work with a clear contract
- Configure a narrow custom Codex agent
- Use the actual Codex built-in roles
- Chain agents through explicit evidence handoffs
- Manage background work without losing its state
- Separate agent threads from worktree isolation
- Coordinate a small team without assuming a team mode
Module 08 Hooks
Build and observe lifecycle hooks, inspect trust and wire contracts, then debug a bounded completion check.
Level 3
Your own system
Plan larger tasks, control permissions and package a workflow for reuse.
Module 09 Advanced features
Plan and implement, compare reasoning, inspect permissions, run headless work and manage a real app schedule.
Module 10 Plugins
Build, install and test a versioned plugin, then distribute it with verified update, rollback and removal steps.
Put it into practiceReal files.
Real files.
Useful small wins.
Seven downloadable projects with deliberate bugs,
reference answers and checks you can run.
Your first project
Fix the search.
Keep the notes.
Meet Orbit Notes: a small project with one practical bug. Give a clear task, review the edit and get all six checks passing.
AGENTS.md notes.cjs checks.cjs
A good first request
Read-only first: confirm the working folder. Read README.md, AGENTS.md and notes.json. Explain the project, list the four note IDs and identify any unsupported setup instructions. Do not change files or install anything.
Use this after opening the practice folder in Codex.
Read the practice lessonsThe reference.
And the practice.
Use the official documentation for current product behavior. Use this course to put it to work through explanations, exercises and evidence. Features can vary by client, version and account.
See sources and course notesA comfortable place to startRead the introduction
Read the introduction
in your language.
The 60 detailed lessons, quizzes and practice files are in English.