gptmock 2026.2.25

OpenAI & Ollama compatible API powered by your ChatGPT account

GPTMock

This is a fork of RayBytes/chatmock. The original Flask + synchronous requests stack has been replaced with FastAPI + async httpx, a layered architecture (router / service / infra), pydantic-settings configuration, and uv as the build system.

OpenAI & Ollama compatible API powered by your ChatGPT account.

gptmock runs a local server that proxies requests to the ChatGPT Codex backend, exposing an OpenAI/Ollama compatible API. Use GPT-5, GPT-5-Codex, and other models directly from your ChatGPT Plus/Pro subscription — no API key required.

Requirements

• Python 3.13+
• Paid ChatGPT account (Plus / Pro / Team / Enterprise)
• uv (for uvx usage)

---

Quick Start (uvx)

The fastest way to run gptmock. No clone, no install — just uvx.

1. Login

uvx gptmock login

A browser window will open for ChatGPT OAuth. After login, tokens are saved to ~/.config/gptmock/auth.json.

2. Start the server

uvx gptmock serve

The server starts at http://127.0.0.1:8000. Use http://127.0.0.1:8000/v1 as your OpenAI base URL.

3. Verify

uvx gptmock info

Tip: Shell Alias

alias gptmock='uvx gptmock'

gptmock login
gptmock serve --port 9000
gptmock info

Note: To install directly from the GitHub repository instead of PyPI:

uvx --from "git+https://github.com/rapidrabbit76/GPTMock" gptmock login
uvx --from "git+https://github.com/rapidrabbit76/GPTMock" gptmock serve

---

Quick Start (Docker)

No build required — pull the pre-built image and run.

1. Create docker-compose.yml

services:
  serve:
    image: rapidrabbit76/gptmock:latest
    container_name: gptmock
    command: ["serve", "--verbose", "--host", "0.0.0.0"]
    ports:
      - "8000:8000"
      - "1455:1455"
    volumes:
      - gptmock-data:/data
    environment:
      - GPTMOCK_HOME=/data
      - CHATGPT_LOCAL_LOGIN_BIND=0.0.0.0
    healthcheck:
      test: ["CMD-SHELL", "python -c \"import urllib.request,sys; sys.exit(0 if urllib.request.urlopen('http://127.0.0.1:8000/health').status==200 else 1)\""]
      interval: 10s
      timeout: 5s
      retries: 5
      start_period: 5s

  login:
    image: rapidrabbit76/gptmock:latest
    command: ["login"]
    ports:
      - "1455:1455"
    volumes:
      - gptmock-data:/data
    environment:
      - GPTMOCK_HOME=/data
      - CHATGPT_LOCAL_LOGIN_BIND=0.0.0.0

volumes:
  gptmock-data:

2. Login

docker compose run --rm --service-ports login login

A URL will be printed. Open it in your browser and complete the OAuth flow. If your browser can't reach the container, copy the full redirect URL from the browser address bar and paste it into the terminal.

3. Start the server

docker compose up -d serve

4. Verify

curl -s http://localhost:8000/health | jq .

Docker Environment Variables

Configure via .env file or docker-compose environment:

Variable	Default	Description
GPTMOCK_PORT	8000	Server port
GPTMOCK_VERBOSE	false	Enable request/response logging
GPTMOCK_REASONING_EFFORT	medium	minimal / low / medium / high / xhigh
GPTMOCK_REASONING_SUMMARY	auto	auto / concise / detailed / none
GPTMOCK_REASONING_COMPAT	think-tags	think-tags / o3 / legacy
GPTMOCK_EXPOSE_REASONING_MODELS	false	Expose reasoning levels as separate models
GPTMOCK_DEFAULT_WEB_SEARCH	false	Enable web search tool by default

---

Usage Examples

Python (OpenAI SDK)

from openai import OpenAI

client = OpenAI(
    base_url="http://127.0.0.1:8000/v1",
    api_key="anything"  # ignored by gptmock
)

resp = client.chat.completions.create(
    model="gpt-5",
    messages=[{"role": "user", "content": "hello world"}]
)
print(resp.choices[0].message.content)

Python (LangChain)

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    base_url="http://127.0.0.1:8000/v1",
    api_key="anything",
    model="gpt-5",
)
response = llm.invoke("hello world")
print(response.content)

curl

curl http://127.0.0.1:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5",
    "messages": [{"role": "user", "content": "hello world"}]
  }'

---

Supported Models

Model	Reasoning Efforts	Status
gpt-5	minimal / low / medium / high	✅ Supported
gpt-5.1	low / medium / high	✅ Supported
gpt-5.2	low / medium / high / xhigh	✅ Supported
gpt-5-codex	low / medium / high	✅ Supported
gpt-5.1-codex	low / medium / high	✅ Supported
gpt-5.1-codex-max	low / medium / high / xhigh	✅ Supported
gpt-5.2-codex	low / medium / high / xhigh	✅ Supported
gpt-5.3-codex	low / medium / high / xhigh	✅ Supported
gpt-5.3-codex-spark	low / medium / high / xhigh	✅ Supported

Deprecated / Unsupported Models

Model	Reason
codex-mini / gpt-5.1-codex-mini	❌ Discontinued by Codex Backend — removed

---

API Endpoints

Method	Path	Description
POST	/v1/chat/completions	OpenAI Chat Completions (stream / non-stream)
POST	/v1/completions	OpenAI Text Completions
POST	/v1/responses	OpenAI Responses API (for LangChain codex routing)
GET	/v1/models	List available models
POST	/api/chat	Ollama-compatible chat
GET	/api/tags	Ollama model list
GET	/health	Health check

---

Features

• Streaming & Non-streaming — real-time SSE and buffered JSON responses
• Structured Output — response_format with json_schema / json_object support
• Tool / Function Calling — including web search with URL citation annotations via responses_tools
• Thinking Summaries — <think> tags, o3 reasoning format, or legacy mode
• Responses API — POST /v1/responses for LangChain and other clients that auto-route codex models
• Ollama Compatibility — drop-in replacement for Ollama API consumers
• Auto Token Refresh — JWT tokens are refreshed automatically before expiry

---

Server Options

gptmock serve [OPTIONS]

Option	Default	Description
--host	127.0.0.1	Bind address
--port	8000	Bind port
--verbose	off	Log request/response payloads
--reasoning-effort	medium	Default reasoning effort level
--reasoning-summary	auto	Reasoning summary verbosity
--reasoning-compat	think-tags	How reasoning is exposed (think-tags / o3 / legacy)
--expose-reasoning-models	off	Show each reasoning level as a separate model in /v1/models
--enable-web-search	off	Enable web search tool by default

---

Web Search

Use --enable-web-search to enable the web search tool by default for all requests. When enabled, the model decides autonomously whether a query needs a web search. You can also enable web search per-request without the server flag by passing the parameters below.

Request Parameters

Parameter	Values	Description
responses_tools	[{"type":"web_search"}]	Enable web search for this request
responses_tool_choice	"auto" / "none"	Let the model decide, or disable

Annotations (URL Citations)

When web search is active, the model may return annotations containing source URLs. These are included automatically in responses:

Non-streaming (stream: false) — annotations are attached to the message:

{
  "choices": [
    {
      "message": {
        "role": "assistant",
        "content": "SpaceX launched 29 Starlink satellites...",
        "annotations": [
          {
            "type": "url_citation",
            "start_index": 0,
            "end_index": 150,
            "url": "https://spaceflightnow.com/...",
            "title": "SpaceX Falcon 9 launch"
          }
        ]
      }
    }
  ]
}

Streaming (stream: true) — annotations arrive as a dedicated chunk before the final stop chunk:

data: {"choices": [{"delta": {"annotations": [{"type": "url_citation", "start_index": 0, "end_index": 150, "url": "https://...", "title": "..."}]}, "finish_reason": null}]}
data: {"choices": [{"delta": {}, "finish_reason": "stop"}]}

Responses API (POST /v1/responses, non-streaming) — annotations are nested inside the output content:

{
  "output": [
    {
      "type": "message",
      "role": "assistant",
      "content": [
        {
          "type": "output_text",
          "text": "SpaceX launched 29 Starlink satellites...",
          "annotations": [
            {
              "type": "url_citation",
              "start_index": 0,
              "end_index": 150,
              "url": "https://spaceflightnow.com/...",
              "title": "SpaceX Falcon 9 launch"
            }
          ]
        }
      ]
    }
  ]
}

Example Request

curl http://127.0.0.1:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5",
    "messages": [{"role":"user","content":"Find current METAR rules"}],
    "stream": true,
    "responses_tools": [{"type": "web_search"}],
    "responses_tool_choice": "auto"
  }'

---

Notes & Limits

• Requires an active, paid ChatGPT account.
• Context length may be partially used by internal system instructions.
• For the fastest responses, set --reasoning-effort to low and --reasoning-summary to none.
• The context size of this route is larger than what you get in the regular ChatGPT app.
• When the model returns a thinking summary, it sends back thinking tags for compatibility with chat apps. Set --reasoning-compat to legacy to use the reasoning tag instead of inline text.
• This project is not affiliated with OpenAI. Use responsibly and at your own risk.

Credits

• Original project: RayBytes/chatmock
• This fork: rapidrabbit76/GPTMock