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pro is available to Pro subscribers and users with a topped-up balance. Model availability changes over time, so prefer selectors unless you need a specific live model ID.
For most applications, use a selector or a live model ID from the Models API:
  • default: first available general-purpose model
  • fast: low-latency model for interactive workloads
  • pro: higher-quality paid model with larger limits or advanced capabilities
  • a concrete model ID, such as gpt-5.4, when you need to pin routing, behavior, or cost

Live model catalog

Use the Models API when you need exact model IDs, current pricing, context windows, modalities, or capability flags:
The response is a live catalog. Do not assume a model ID will always be present.

Models API

Learn how to read tiers, pricing, context windows, modalities, and capability flags.

When to use a specific ID

Use a concrete model ID only when you need to pin behavior for evaluation, routing, or cost controls. Before sending traffic, check the live model catalog and confirm the model supports the feature you need. For example:

Access tiers

turbo models are fast models available to anonymous and free-token users. They are a good fit for low-latency and cost-sensitive workloads. pro models are available on Pro subscriptions or paid balances. They may include larger context windows, reasoning, vision, JSON mode, streaming, or tool calling depending on the model record. See Limits for rate limits and token availability by access type.