CODEX.md

CODEX.md is a project-level Markdown memory file that the OpenAI Codex CLI loads to bootstrap an AI coding agent with persistent project instructions, coding conventions, build and test commands, and team conventions. The OpenAI Codex CLI now standardizes on AGENTS.md as the canonical filename, with CODEX.md and codex.md historically used and still recognized as fallback configuration filenames. Files are discovered through a three-tier hierarchy spanning the user's home directory, the Git repository root, and the current working directory, with closer files overriding earlier guidance when concatenated into the model prompt.

CODEX.md is profiled on the APIs.io network. Tagged areas include AI Agents, AI Copilot, Coding Standards, Configuration, and Developer Workflow.

CODEX.md’s developer surface includes documentation, GitHub presence, and 2 more developer resources.

🌐 Visit website 📡 Source on GitHub

9.2/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5

0 APIs

AI AgentsAI CopilotCoding StandardsConfigurationDeveloper WorkflowMemoryOpenAI Codex

Kin Score

Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5

Composite quality — 9.2/100 · minimal

Contract Quality 0.0 / 25

Developer Ergonomics 1.7 / 20

Commercial Clarity 0.0 / 20

Operational Transparency 0.7 / 13

Governance 0.0 / 12

Discoverability 6.8 / 10

Agent readiness — 0/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 15

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/codex-md: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Resources

Documentation 2

Reference material describing how the API behaves

Specification

Specification

Documentation

Documentation

Build 1

SDKs, sample code, and the tooling you integrate with

GitHub

GitHub

Other 1

Properties that don't map to a standard resource type

Landing Page

Landing Page

Source (apis.yml)

aid: codex-md
url: https://raw.githubusercontent.com/api-evangelist/codex-md/refs/heads/main/apis.yml
name: CODEX.md
tags:
- AI Agents
- AI Copilot
- Coding Standards
- Configuration
- Developer Workflow
- Memory
- OpenAI Codex
kind: standard
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source: []
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/codex-md.png
access: 3rd-Party
created: '2025-01-01'
modified: '2026-04-26'
position: Consumer
description: CODEX.md is a project-level Markdown memory file that the OpenAI Codex CLI loads to bootstrap an AI coding agent
  with persistent project instructions, coding conventions, build and test commands, and team conventions. The OpenAI Codex
  CLI now standardizes on AGENTS.md as the canonical filename, with CODEX.md and codex.md historically used and still recognized
  as fallback configuration filenames. Files are discovered through a three-tier hierarchy spanning the user's home directory,
  the Git repository root, and the current working directory, with closer files overriding earlier guidance when concatenated
  into the model prompt.
apis: []
common:
- type: Specification
  url: https://developers.openai.com/codex/guides/agents-md
- type: Documentation
  url: https://developers.openai.com/codex/cli
- type: GitHub
  url: https://github.com/openai/codex
- type: Landing Page
  url: https://developers.openai.com/codex
x-features:
- Markdown-based freeform instruction format with no mandated schema
- Loaded automatically by Codex CLI before any task execution
- Three-tier discovery (home directory, Git repo root, current directory)
- Override file convention (AGENTS.override.md / CODEX.override.md)
- Concatenated merge order with closer files taking precedence
- Equivalent role to CLAUDE.md (Claude Code) and .cursorrules (Cursor)
- Designed to encode build commands, test commands, lint rules, and conventions
- Agentic memory primitive for persistent project context across CLI sessions
x-use-cases:
- Pin a repository to specific package managers, formatters, and linters
- Document non-obvious build, test, or migration commands for the agent
- Establish project-wide coding standards (naming, error handling, imports)
- Capture team norms (PR descriptions, commit style, branch naming)
- Restrict the agent from touching protected files or directories
- Bridge organizational knowledge into AI-assisted development sessions
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
specificationVersion: '0.19'