o4-mini

The official OpenAI replacement is gpt-5.4-mini — it uses a unified reasoning architecture, delivers better benchmark performance, and is dramatically cheaper at $0.15/$0.60 per 1M tokens (vs o4-mini's $1.10/$4.40). If you need stronger reasoning, use gpt-5.5. If you want a cross-provider alternative, deepseek/deepseek-v4-flash offers competitive reasoning at similar price points. All are available through TheRouter with the same API pattern.

o4-mini is a smaller, faster, and cheaper reasoning model optimized for throughput and cost efficiency ($1.10/$4.40 vs o3's $2/$8 per 1M tokens). o3 is the flagship with deeper reasoning — better at the hardest math, coding, and science problems. o4-mini was actually the best on some benchmarks (AIME 2024/2025) due to its efficiency, but o3 outclasses it on pure reasoning depth tasks like FrontierMath and GPQA Diamond. For most production workloads, o4-mini offered the better speed-cost-reasoning balance — which is why gpt-5.4-mini now fills that role even better.

Yes. o4-mini was trained via reinforcement learning to use tools autonomously, reasoning about when and how to deploy them. It has full access to web search, Python execution, file analysis, visual reasoning, and memory within ChatGPT. In the API, it supports standard function calling — you define your own tools via the tools parameter, and o4-mini will decide when to call them and how to chain them together for multi-step workflows.

Yes. o4-mini was the first small reasoning model from OpenAI to integrate images directly into its chain of thought — it doesn't just see images, it reasons with them. You can upload charts, diagrams, whiteboard sketches, or even low-quality images, and the model can interpret and analyze them. It supports image input via the standard vision API format. However, o4-mini cannot generate images — it's text+image input, text-only output.