Compare models
Put up to 4 models beside each other — token prices, context windows, capabilities and provider, from the same catalogue the model pages read.
| Attribute | S1s1 | S2.1 Pros2.1-pro | GPT-6 Lunagpt-6-luna |
|---|---|---|---|
| Pricing | |||
| Input | $0 / 1M | $0 / 1M | $0.10 / 1M |
| Output | $0 / 1M | $0 / 1M | $0.50 / 1M |
| Cache Write (5m) | Not applicable | Not applicable | $0.10 / 1M |
| Cache Write (1h) | Not applicable | Not applicable | $0.10 / 1M |
| Cache Read | Not applicable | Not applicable | $0.10 / 1M |
| Web Search | $0 / 1M | $0 / 1M | $0 / 1M |
| Context | |||
| Max context | N/A | N/A | 1.1M |
| Max output | N/A | N/A | N/A |
| Capabilities | |||
| Vision | No | No | Yes |
| Function Calling | No | No | Yes |
| JSON Mode | No | No | Yes |
| Streaming | No | No | Yes |
| Catalogue | |||
| Provider | Fish Audio | Fish Audio | OpenAI |
| Category | voice | voice | chat |
| Charge type | Pay As You Go | Pay As You Go | Pay As You Go |
| Released | 2026-07-29 | 2026-07-29 | — |
| Description | |||
| Summary | Fish Audio S1 text-to-speech. Billed per UTF-8 byte of input text. | 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. |