Use BigModel.io with Cursor

Cursor lets you add your own provider keys for chat models. With an OpenAI key slot, a base URL override and a custom model name, its chat and agent can call BigModel.io models over https://bigmodel.io/v1.

Cursor's official API keys page documents custom provider keys but no longer mentions the Override OpenAI Base URL toggle. The steps below follow community reports from current Cursor releases. If your version has no override field, Cursor cannot be pointed at BigModel.io.

#What uses your key

• Chat and agent requests with the models you add use your key and are billed to your BigModel.io balance.
• Tab completion and other Cursor features keep using Cursor's own models and plan. Custom keys apply to chat models only.
• All requests go through Cursor's servers before they reach BigModel.io, so the base URL must be publicly reachable. https://bigmodel.io/v1 is; a localhost proxy is not.

#Before you start

1. Create a key in API Keys in a group that serves the models you want. Cursor sends Chat Completions requests, so every group that serves text models works.
2. Check the key with a minimal request:

curl https://bigmodel.io/v1/chat/completions \
  -H "Authorization: Bearer $BIGMODEL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"glm-5.3","messages":[{"role":"user","content":"ping"}]}'

#Configure Cursor

Menu names change between releases; look for the same fields if yours differ.

1. Open Cursor Settings → Models.
2. Under API Keys, paste your BigModel.io key into OpenAI API Key.
3. Turn on Override OpenAI Base URL (community-reported, directly under the OpenAI key) and enter https://bigmodel.io/v1. Do not add /chat/completions.
4. Choose Add model and enter the exact model ID, for example glm-5.3, kimi-k3 or deepseek-v4-pro.
5. Enable the new model and select it in the chat or agent model picker.

While the override is on, requests for Cursor's built-in OpenAI model names also go to BigModel.io and may fail. Turn off the built-in models you do not need, or turn the override off when you want them.

#Choosing a model

Use IDs exactly as shown on the model page: lowercase with dots (glm-5.3, kimi-k3, deepseek-v4-pro, minimax-m3). Agent mode needs reliable tool calls; test with a short task before a large refactor.

#Verify the setup

Select your added model in the chat panel, send "ping", then open Usage. The request should appear with the model ID you entered. If it does not, Cursor answered with one of its own models.

#Troubleshooting

Verification fails when you save the key. Cursor may verify with one of its default OpenAI model names, which your key's group does not serve. Add your own model, keep only that one enabled, then verify again. A chat request that shows up in Usage is the real test.

503 api_error: No available accounts: no available accounts supporting model: .... The model name in Cursor does not match a model your key's group serves. Copy the ID from the model page exactly.

404 on every request. The base URL is wrong. Use https://bigmodel.io/v1, not https://bigmodel.io or .../v1/chat/completions.

401 INVALID_API_KEY. The key was pasted with spaces, was deleted, or belongs to another account. Copy it again from API Keys.

403 INSUFFICIENT_BALANCE or 429 API_KEY_QUOTA_EXHAUSTED. Top up in Billing or raise the key's quota. A 429 rate_limit_exceeded names the key window (5h, 1d or 7d) that is used up.

Built-in models stopped working. The override sends all OpenAI-model requests to BigModel.io. Turn it off when you want Cursor's built-in models.

Tab completion does not use BigModel.io. Expected. Tab always runs on Cursor's models.

#Related

• Configure Base URL in Codex, Claude Code, Cursor and Cline
• Cline for a VS Code agent with a dedicated OpenAI Compatible provider.
• Continue for an open-source assistant whose chat runs fully on your own key.
• Claude Code for a terminal agent on the Anthropic protocol.