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 3 more developer resources.

🌐 Visit website 📡 Source on GitHub

0 APIs

AI Agents AI CopilotCoding StandardsConfigurationDeveloper WorkflowMemoryOpenAI Codex

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

Company 1

The organization behind the API

Website

Website

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
x-type: convention
tags:
- AI Agents
- AI Copilot
- Coding Standards
- Configuration
- Developer Workflow
- Memory
- OpenAI Codex
kind: standard
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - none
  generated: '2026-08-28'
  method: derived
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: Consuming
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: Website
  url: https://www.openai.com/
- 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: '0.23'

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This provider

curl "https://apis.io/api/v1/providers/codex-md"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/codex-md/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/codex-md/evidence"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.