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| Attribute | S2.1 Pros2.1-pro | GPT-6 Lunagpt-6-luna | GPT-6 Luna Progpt-6-luna-pro | S2 Pros2-pro |
|---|---|---|---|---|
| Pricing | ||||
| Input | $0 / 1M | $0.10 / 1M | $0.10 / 1M | $0 / 1M |
| Output | $0 / 1M | $0.50 / 1M | $0.50 / 1M | $0 / 1M |
| Cache Write (5m) | Not applicable | $0.10 / 1M | $0.10 / 1M | Not applicable |
| Cache Write (1h) | Not applicable | $0.10 / 1M | $0.10 / 1M | Not applicable |
| Cache Read | Not applicable | $0.10 / 1M | $0.10 / 1M | Not applicable |
| Web Search | $0 / 1M | $0 / 1M | $0 / 1M | $0 / 1M |
| Context | ||||
| Max context | N/A | 1.1M | 1.1M | N/A |
| Max output | N/A | N/A | N/A | N/A |
| Capabilities | ||||
| Vision | No | Yes | Yes | No |
| Function Calling | No | Yes | Yes | No |
| JSON Mode | No | Yes | Yes | No |
| Streaming | No | Yes | Yes | No |
| Catalogue | ||||
| Provider | Fish Audio | OpenAI | OpenAI | Fish Audio |
| Category | voice | chat | chat | voice |
| Charge type | Pay As You Go | Pay As You Go | Pay As You Go | Pay As You Go |
| Released | 2026-07-29 | — | — | 2026-07-29 |
| Description | ||||
| Summary | Fish Audio S2.1 Pro text-to-speech. Billed per UTF-8 byte of input text. | GPT-6 Luna is the fast, cost-efficient model in OpenAI's GPT-6 series, optimized for high-volume and latency-sensitive workloads such as chat, classification, and lightweight agentic tasks. It combines low-cost, responsive inference with the GPT-6 family’s improvements in factual reliability and clear, concise communication. At higher reasoning effort, GPT-6 Luna can also handle complex software engineering and computer-use workflows that previously required a Sol-tier model, making it a versatile choice for scalable production applications that need to balance speed, cost, and capability. | GPT-6 Luna Pro uses the same underlying model as GPT-6 Luna, but runs with reasoning.mode set to pro for higher-quality responses on complex tasks. It combines Luna's speed and cost efficiency with deeper reasoning and more reliable multi-step execution, making it well suited for advanced coding, computer use, and agentic workflows where higher solution quality is needed without moving to a larger GPT-6 tier. | Fish Audio S2 Pro text-to-speech. Billed per UTF-8 byte of input text. |