o3 API
Advanced reasoning model that thinks step-by-step for complex math, science, and coding problems.
💰 Save up to 70% vs official OpenAI pricingo3 — cheaper than the official OpenAI API
Access o3 through AI API Hub and pay less per token. Same OpenAI-compatible endpoint, lower cost.
Technical Specifications
| Provider | OpenAI |
| Model Family | o3 |
| Release Date | 2026-05 |
| Context Window | 200K |
| Max Output Tokens | 100,000 |
| Input Price | $2.00 / 1M tokens |
| Output Price | $8.00 / 1M tokens |
| Vision Support | No |
| Function Calling | No |
| JSON Mode | No |
| Streaming | No |
| Fine Tuning | Not Available |
| Status | Active ✓ |
Overview
o3 is OpenAI's current reasoning model, released in 2026-05. Advanced reasoning model that thinks step-by-step for complex math, science, and coding problems.
For developers, the headline numbers are a 200K context window and up to 100,000 output tokens per response — enough headroom for chain-of-thought and complex reasoning without chunking your input. Priced at $2.00/1M input and $8.00/1M output, it sits in the mid-range — a sensible default for most production workloads.
On the capability side, o3 exposes 3 features: Reasoning, Coding, Math. Note that fine-tuning isn't supported — you'll work with the base model. It's text-only, so route image or audio workloads elsewhere.
The practical appeal of routing o3 through AI API Hub is simplicity: one OpenAI-compatible endpoint, USDT & USDC payments, no credit card, and you're calling the API in under 30 seconds — just swap your base URL.
What Makes o3 Different
How o3 is used
o3 is deployed for problems that need structured thinking — math derivations, logic puzzles, scientific analysis, and multi-step research synthesis. The reasoning chain adds latency, so reserve it for tasks where a standard chat model produces shallow or incorrect answers. For routine Q&A and summarization, a cheaper sibling model is more cost-effective.
Pricing position within OpenAI
o3 sits in the middle of OpenAI's pricing at $2.00/1M input — 34% below the lineup average ($0.10 cheapest, $20.00 most expensive). 6 siblings cost less, 4 cost more. This mid-tier positioning makes it a sensible default when you're unsure which variant to pick.
o3's role in the lineup
Within OpenAI's lineup, o3 is a mid-tier option — balanced between cost and capability. The reasoning family has 3 active variants, and o3 occupies the lower end. This makes it a safe default for production workloads where you're not sure which tier to pick.
Real-world use cases
Real-world deployments: math problem solving, scientific research synthesis, multi-step logical analysis, and structured decision support systems. o3 excels where standard chat models produce shallow answers — the reasoning chain catches edge cases that faster models miss.
vs sibling models
What makes o3 different from sibling models: compared to GPT-5.5 ($3.00/1M more expensive, 256K vs 200K context (larger)); GPT-5.4 ($0.50/1M more expensive, 256K vs 200K context (larger)); GPT-4.1 ($0.00/1M cheaper, 1M vs 200K context (larger)). Choose o3 when step-by-step reasoning matters more than speed.
API Examples
Python
from openai import OpenAI
client = OpenAI(
api_key="YOUR_API_KEY",
base_url="https://api.apiyihe.org/v1"
)
response = client.chat.completions.create(
model="o3",
messages=[
{"role": "user", "content": "Hello"}
]
)
print(response.choices[0].message.content)JavaScript / Node.js
import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.API_KEY,
baseURL: "https://api.apiyihe.org/v1"
});
const response = await client.chat.completions.create({
model: "o3",
messages: [
{ role: "user", content: "Hello" }
]
});
console.log(response.choices[0].message.content);cURL
curl https://api.apiyihe.org/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"model": "o3",
"messages": [
{"role": "user", "content": "Hello"}
]
}'Supported Features
| Vision / Image Input | ❌ Not Available |
| Audio / Voice Input | ❌ Not Available |
| Function Calling | ❌ Not Available |
| JSON Mode | ❌ Not Available |
| Streaming | ❌ Not Available |
| Fine-Tuning | ❌ Not Available |
| Multimodal | ❌ Not Available |
Benchmark Scores
| Benchmark | Score |
|---|---|
| MMLU | Not Publicly Available |
| GPQA | Not Publicly Available |
| SWE-Bench | Not Publicly Available |
| HumanEval | Not Publicly Available |
| GSM8K | Not Publicly Available |
| MATH | Not Publicly Available |
| MMMU | Not Publicly Available |
Pricing History
o3 was released in 2026-05 by OpenAI and is currently publicly available via AI API Hub.
Current Pricing: $2.00 per 1M input tokens · $8.00 per 1M output tokens. Pay-as-you-go with no minimum commitment.
Pricing Model: Token-based billing (pay per use). No subscription fees. No hidden costs.
💡 OpenAI occasionally updates pricing. AI API Hub reflects current pricing in real-time. All prices in USD. Pay with USDT or USDC — no currency conversion fees.
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Frequently Asked Questions
What is o3?
o3 is OpenAI's current reasoning model. Advanced reasoning model that thinks step-by-step for complex math, science, and coding problems. It offers a 200K context window and supports Reasoning, Coding, Math. You can access it through AI API Hub using USDT or USDC — no credit card required.
How much does o3 cost?
o3 is priced at $2.00 per 1M input tokens and $8.00 per 1M output tokens, billed pay-as-you-go with no minimum. Through AI API Hub you can start with as little as $5 and scale from there.
o3 vs Claude Opus 4.8?
They're built for different jobs. o3 costs $2.00/1M input with a 200K window; Claude Opus 4.8 runs $5.00/1M input with 1M. o3 is the more cost-effective pick and still brings chain-of-thought. See the full side-by-side at /compare/o3-vs-claude-opus-4.8/.
o3 context window?
o3 has a 200K context window, capable of processing up to 200,000 tokens in a single request. Maximum output tokens: 100,000.
Does o3 support function calling?
No, o3 does not natively support function calling. For function calling use cases, consider OpenAI's flagship models.
Is o3 multimodal?
No, o3 is a text-only model. For multimodal use cases, consider models with vision/audio capabilities.
o3 API rate limits?
o3 rate limits: 10K RPM. Higher tier plans offer increased throughput. For high-volume production use, consider OpenAI's faster variant models.
How to access o3 API?
Access o3 through AI API Hub: (1) Register at api.apiyihe.org/register?aff=8JZC, (2) Deposit USDT/USDC, (3) Get your API key instantly, (4) Use the OpenAI-compatible endpoint https://api.apiyihe.org/v1 with model name "o3". Start building in under 30 seconds.