OpenAI: GPT-5.1-Codex-Mini

What sets GPT-5.1-Codex-Mini apart from the obvious alternatives is not capability but economics: it is a smaller, faster version of GPT-5.1-Codex priced at $0.25 per million tokens, a fifth of what the larger coding variants in this family list. That makes it the sensible pick for high-volume, latency-sensitive coding chores, say running an automated agent that opens many small pull requests or lints and patches files across a large repository where cost per call adds up quickly. Despite the trimmed size it keeps the same 400,000-token context window, larger than most models here, plus chain-of-thought reasoning, tool and function calling, vision input and structured JSON outputs. Compared with general assistants such as Claude, ChatGPT and Gemini, it stays coding-focused, and unlike Cursor, which is an editor, it is the underlying model; against its own siblings its edge is throughput and price rather than raw depth. There is no free tier, so usage is still billed per token, just at a lower rate. Ideal for developers running frequent, well-defined tasks who need to keep the bill down without dropping to a tiny context window. Choose it for scale and speed on routine work; step up to the fuller variants when a problem demands the model's deepest reasoning.