LinkModel API Documentation

Codex should use LinkModel’s Responses-compatible endpoint. Use GPT-series LinkModel models only.

Configure

Set your LinkModel API key:

export LINKMODEL_API_KEY="<YOUR_API_KEY>"

Add a LinkModel provider to ~/.codex/config.toml:

model = "gpt-5.3-codex"
model_provider = "linkmodel"

[model_providers.linkmodel]
name = "LinkModel"
base_url = "https://api.linkmodel.ai/v1"
env_key = "LINKMODEL_API_KEY"
wire_api = "responses"

Start Codex:

codex

Recommended Models

Use GPT-series models that are exposed on the Responses endpoint:

Model	Use case
`gpt-5.3-codex`	Agentic coding and Codex workflows.
`gpt-5.6-sol`	GPT reasoning and coding workflows.
`gpt-5`	General GPT chat and reasoning workflows.

Verify

Open /status in Codex and confirm the active provider is linkmodel. If Codex does not pick up shell environment variables, put the key in ~/.codex/.env:

LINKMODEL_API_KEY=<YOUR_API_KEY>

Restart Codex after changing ~/.codex/config.toml or ~/.codex/.env.

Official Reference

OpenAI Codex repository
Codex model provider source

​Configure

​Recommended Models

​Verify

​Official Reference

Configure

Recommended Models

Verify

Official Reference