use-cases/codebase-onboarding.md Codex Docs, 2026-04-15 06:44 UTC → 2026-04-15 18:31 UTC

1# Understand large codebases | Codex use cases1# Understand large codebases | Codex use cases

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3Codex use cases

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5![](/assets/OpenAI-black-wordmark.svg)

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7![Codex](/assets/OAI_Codex-Lockup_Fallback_Black.svg)

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9Codex use case

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11# Understand large codebases

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13Trace request flows, map unfamiliar modules, and find the right files fast.

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15Difficulty **Easy**

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17Time horizon **5m**

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19Use Codex to map unfamiliar codebases, explain different modules and data flow, and point you to the next files worth reading before you edit.

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21## Best for

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23 - New engineers onboarding to a new repo or service

24 - Anyone trying to understand how a feature works before changing it

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26# Contents

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3[← All use cases](https://developers.openai.com/codex/use-cases)28[← All use cases](https://developers.openai.com/codex/use-cases)

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5Copy page [Export as PDF](https://developers.openai.com/codex/use-cases/codebase-onboarding/?export=pdf)30Copy page [Export as PDF](https://developers.openai.com/codex/use-cases/codebase-onboarding/?export=pdf)