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Using OpenAI Codex Confidently: A Practical Learning Path

A hands-on course for learners who already understand programming fundamentals and want to use OpenAI Codex effectively for real development work. You will learn how to set up Codex, give it useful context, review and test its output, manage larger tasks, and build safe, repeatable workflows. Features and access method

480 min6 modulesBeginner friendly
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Free to take. This course does not use any Learning Credits.

What you’ll be able to do

By the end, you will be able to use Codex to explore unfamiliar codebases, plan and implement changes, debug issues, write tests and documentation, review generated code, and apply suitable security and quality controls before accepting changes.

Course outline

A clear route from first principles to practical confidence

  1. 01

    Getting oriented with Codex

    • Codex capabilities, limitations and suitable use cases
    • Available access methods and account or workspace setup
    • Connecting Codex to a project and understanding its working context
    • Setting expectations: delegation, supervision and human review
    • Practical exercise: ask Codex to inspect a small project and summarise its structure
  2. 02

    Giving Codex effective instructions

    • Turning a broad goal into a precise coding task
    • Providing relevant context, constraints, conventions and acceptance criteria
    • Using repository instructions and project documentation effectively
    • Asking for a plan before requesting implementation
    • Practical exercise: improve a vague prompt into a task specification and implementation plan
  3. 03

    Exploring and modifying an existing codebase

    • Finding relevant files, symbols, tests and configuration
    • Asking Codex to trace behaviour across a codebase
    • Breaking feature work into small, reviewable steps
    • Requesting targeted edits rather than unrestricted rewrites
    • Practical exercise: add a small feature to an existing project and inspect the proposed diff
  4. 04

    Testing, debugging and verification

    • Providing a useful bug report with reproduction steps and expected behaviour
    • Using logs, stack traces and failing tests as evidence
    • Generating focused tests and identifying missing edge cases
    • Running checks and interpreting failures rather than accepting claims
    • Practical exercise: diagnose a failing test, apply a fix and add regression coverage
  5. 05

    Working effectively with an agent

    • Planning work as milestones and defining stopping points
    • Reviewing proposed actions, file changes and command results
    • Recovering from an incorrect approach and refining instructions
    • Handling ambiguity, conflicting requirements and incomplete context
    • Practical exercise: coordinate a multi-step refactor with checkpoints and a rollback point
  6. 06

    Code quality, security and safe use

    • Reviewing correctness, maintainability, accessibility and performance
    • Recognising insecure patterns, data exposure and unsafe dependencies
    • Protecting secrets, credentials, personal data and proprietary code
    • Using least privilege, isolated environments and version control
    • Practical exercise: conduct a security and quality review of Codex-generated code