# OpenAI GPT-5.6 Terra Pro API

> GPT-5.6 Terra Pro is the same GPT-5.6 Terra model, the balanced middle tier of OpenAI's GPT-5.6 family, served in OpenAI's pro reasoning mode instead of standard mode. Pro mode applies more model work to each request and returns a single final answer, which OpenAI says can improve reliability on difficult problems while increasing latency and token usage. It fits harder coding, review or analysis tasks where Terra's tier is preferred but extra quality on a single answer matters.

Source: https://www.sandbase.ai/models/openai/gpt-5.6-terra-pro
API reference: https://www.sandbase.ai/models/openai/gpt-5.6-terra-pro/docs

## Facts

- Provider: OpenAI
- Type: Language model
- Model ID: `openai/gpt-5.6-terra-pro`
- Price: $2 per 1M input tokens, $12 per 1M output tokens
- Context window: 1.1M tokens, up to 128K output tokens
- Capabilities: chat, vision, reasoning, structured output, function calling
- Billing: pay per use from one SandBase balance; no provider account or subscription needed

## Call it

- Responses API: `POST https://api.sandbase.ai/v1/responses`
- Chat Completions API: `POST https://api.sandbase.ai/v1/chat/completions`

```bash
curl -X POST https://api.sandbase.ai/v1/responses \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "openai/gpt-5.6-terra-pro",
  "input": "Hello",
  "max_output_tokens": 2048
}'
```

## FAQ

### How do I call OpenAI GPT-5.6 Terra Pro through SandBase?

Create a SandBase API key, then send requests with the model ID "openai/gpt-5.6-terra-pro" to Responses API (/v1/responses) or Chat Completions API (/v1/chat/completions) at https://api.sandbase.ai. The request examples on this page show the exact payload.

### How much does OpenAI GPT-5.6 Terra Pro cost?

$2 per 1M input tokens and $12 per 1M output tokens, billed per request from your SandBase balance. Discounts, when available, are shown in the pricing on this page.

### What is the context window of OpenAI GPT-5.6 Terra Pro?

1.1M tokens of context, with up to 128K output tokens per response.

### Which features does OpenAI GPT-5.6 Terra Pro support?

OpenAI GPT-5.6 Terra Pro supports vision (image input), reasoning, function calling, structured output. See Specifications above for the full list.

### Do I need a separate OpenAI account?

No. One SandBase API key and balance gives you access to OpenAI GPT-5.6 Terra Pro and the other models in the catalog; you do not need to sign up with OpenAI separately.