OpenAI: GPT-5.4 Nano

The buyer's real question here is how much reasoning quality to surrender for price and speed, and this is the variant that pushes hardest toward the cheap-and-fast end. As the most lightweight member of the GPT-5.4 family, it is tuned for speed-critical, high-volume tasks at 0.20 dollars per million tokens, the lowest price among its GPT-5.4 siblings. A fitting use case is classifying or tagging a large stream of support tickets in real time, where throughput and cost matter more than deep deliberation. Despite the nano positioning, it keeps the family's headline features: a 400,000-token context window bigger than most models listed here, image input, an optional chain-of-thought reasoning mode, tool and function calling, and structured JSON output, with an August 2025 knowledge cutoff. Unlike frontier options such as Claude Sonnet 5 or a full-size Gemini, this trades peak reasoning depth for latency and unit economics, and unlike a mini-tier sibling it goes further on cost at the expense of capability. The one clear drawback is no free tier, so every request is billed. Ideal for developers running high-volume, latency-sensitive research and writing pipelines who need adequate reasoning at minimal cost. Pick it for scale and speed; step up to a larger variant when a task genuinely rewards deeper reasoning.