Chatbox

Chatbox is a desktop and mobile chat client with a simple custom-provider form. Setup takes under a minute.

Prerequisites

• Chatbox installed.
• A CAPI API key.

Configure

1. Open Settings → Model.
2. Choose Add Custom Provider.
3. Set API Mode to OpenAI API Compatible.
4. Fill in:

1. Click Check to validate. A green result means the endpoint and key are correct.

Add more models by repeating the model entry — Chatbox keeps them under one provider, so switching is a dropdown change rather than a settings edit.

Suggested models

Image input

Attach an image and pick a multimodal model. Chatbox sends it as a content array; if the model does not support vision you get a 400 explaining the unsupported content type.

Sync across devices

Chatbox's paid sync carries provider settings between desktop and mobile, so the API key is stored by the sync service. On a shared machine, prefer a key scoped narrowly and rotated periodically.

Web search and tools

Chatbox's built-in tools (web search, URL fetch) run client-side and are separate from the model. CAPI models with native tool calling work, but Chatbox's own tools do not depend on them.

Troubleshooting

"Check" fails with 404. API Host must end at /v1, with /chat/completions in the path field — not concatenated into the host.

Replies are empty. Some models return reasoning in a separate field. Disable any "show reasoning only" option, or switch model.

Slow streaming. Chatbox buffers by default. Lower the stream buffer setting, or test the same key with cURL to confirm the endpoint itself is fast:

curl https://capi.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $CAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"gpt-5.6","messages":[{"role":"user","content":"hi"}],"stream":true}'

Next steps

• Cherry Studio
• LLM API quickstart