OpenAI o3
OpenAI·Apr 2025reasoningproprietary
68.9
modhub Index
o3 was the peak of OpenAI's dedicated reasoning line before GPT-5 absorbed it. It could invoke web search, Python and image manipulation inside its chain of thought, and its 80% price cut in June 2025 (to $2/$8) made deep reasoning broadly affordable. The GPT-5 family has since superseded it, but o3 is still served in the API and remains a familiar benchmark reference point.
Benchmark results
Where it shines
- Strong multi-step reasoning with tools in the loop
- Thinking-with-images for visual problem solving
- Aggressive pricing after the 2025 cut
Alternatives to OpenAI o3
The sparse-attention release that halved DeepSeek's already-lowest-in-class prices while keeping GPT-class quality.
A trillion-parameter open reasoning agent that can chain 200–300 tool calls — the open-weights agentic standout of late 2025.
Google's 2025 workhorse flagship — first mainstream thinking model with a 1M context, still widely deployed.
The model that made 30-hour autonomous coding sessions real — 77.2% SWE-bench Verified and a 1M-token context beta at $3/$15.
Frequently asked questions
- How much does the OpenAI o3 API cost?
- OpenAI o3 costs $2 per million input tokens and $8 per million output tokens, with cached input at $0.5 per million. A workload of 10M input and 1.5M output tokens per month costs about $32.00.
- What is the context window of OpenAI o3?
- OpenAI o3 supports a context window of 200,000 tokens (200K), with up to 100K output tokens per response.
- Is OpenAI o3 open source?
- No — OpenAI o3 is a proprietary model available through OpenAI's API and partner platforms.
- What are the best alternatives to OpenAI o3?
- The closest alternatives by overall capability are DeepSeek V3.2, Kimi K2 Thinking, Gemini 2.5 Pro, Claude Sonnet 4.5. See the comparison pages for detailed head-to-head breakdowns.