Chatbox

Chatbox is a multi-model AI chat client that covers every platform — Windows / macOS / Linux / iOS / Android / Web.

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Download and install

• Official site: https://chatboxai.app
• Download and install the version for your platform — no account needed to use BYOK (bring your own key) mode

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The two protocols

LMU AI supports two connection protocols; choose one based on the model type:

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Opening the add-provider entry point

Both protocols are configured from the same entry point:

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Method 1: Anthropic protocol (Claude and Chinese models)

Step 1 — Create a provider

After opening the new-provider window from the entry point above:

1. API Mode: select Claude API (Anthropic Compatible)
2. Name: anything you like (e.g. LMU AI)

Step 2 — Enter the API details

• API Host: enter the LMU AI API address (without /v1)

  https://api.lmuai.com

• API Key: enter the sk- key generated in the console

Step 3 — Add models

Chatbox's default list may not include the latest models, so you need to add them manually. On the provider settings page, find the Model section → click New / Add Model and enter the model ID, for example:

• claude-opus-5
• claude-sonnet-5
• claude-haiku-4-5
• deepseek-v4-pro
• qwen3.8-max-preview
• glm-5.2
• kimi-k3

For the full list of available models, see the Model Gallery.

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Method 2: OpenAI protocol (GPT models)

Step 1 — Create a provider

After opening the new-provider window from the entry point above:

1. API Mode: select OpenAI Responses API Compatible (not OpenAI API Compatible)
2. Name: anything you like (e.g. LMUAI-GPT)

Step 2 — Enter the API details

Chatbox automatically joins the Host, /v1, and Path into the full request address https://api.lmuai.com/v1/responses, and the full assembled URL is shown live below the fields.

Once filled in as above, the screen looks like this:

Step 3 — Add models

In the Model section, click New and enter the model ID:

• gpt-5.6-sol
• gpt-5.6-terra
• gpt-5.6-luna
• gpt-5.5
• gpt-5.4
• gpt-5.2

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Usage

Back on the main screen, click the model selector at the top, switch to the provider and model you just added, and start chatting.

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Common issues

Does the API Host need /v1?

No. Always enter the Chatbox API Host field up to the domain only: https://api.lmuai.com.

Chatbox appends /v1 itself:

• Anthropic protocol: becomes https://api.lmuai.com/v1/messages
• OpenAI Responses protocol: set Path to /responses, which becomes https://api.lmuai.com/v1/responses

If you add an extra /v1 in the Host, you get a broken 404 path like …/v1/v1/....

Why pick OpenAI Responses instead of the plain OpenAI API Compatible?

Chatbox's OpenAI API Compatible uses the older /chat/completions endpoint; LMU AI's OpenAI protocol uses the newer Responses API (/v1/responses), so you must pick OpenAI Responses API Compatible here and set API Path to /responses.

Chatbox's model list doesn't have Claude Opus 5 / GPT-5.6?

Chatbox's built-in preset model list updates with a delay, so new models need to be added manually via Add Model in the provider configuration — just enter the corresponding model ID. For available models, see the Model Gallery.

Changes don't take effect?

After saving, we recommend restarting the Chatbox client once, or reselecting the model in the chat screen.

401 / 403 errors?

Check in order:

1. Is the API Key the sk- key generated in the LMU AI console (not an official Anthropic / OpenAI key)?
2. Is the API Host wrong (both protocols use https://api.lmuai.com, neither with /v1; for the OpenAI protocol, also check that API Mode is OpenAI Responses API Compatible and API Path is /responses)?
3. Does your current plan / billing group include the model you're calling?

Last updated: 2026-08-26