o3
o3 is a well-rounded, powerful OpenAI reasoning model for math, science, coding and visual reasoning, and it is also strong at technical writing and instruction following.
Pricing: Input 400 credits / 1M tokens (≈ $2.00), Output 1600 credits / 1M tokens (≈ $8.00).
Prices updated
How can I help you today?
This demo page does not include the full memory features of the client. For the complete experience, please use the client or the CLI.
More AI models from OpenAI
Latest and popular AI models
o3 API on ModelFold
o3 is a well-rounded, powerful OpenAI reasoning model for math, science, coding and visual reasoning, and it is also strong at technical writing and instruction following. Try o3 in the ModelFold Playground, then call it from your own code through an OpenAI-compatible chat completions API.
What Is the o3 API
o3 at a glance
o3 is a chat model from OpenAI. It accepts text, images and files (such as PDF) as input and returns text, with a context window of up to 200K tokens.
Use it without hosting anything
On ModelFold you call o3 with a single API key — no model weights to download and no inference servers to run. The same key also works for the other chat, image, video and audio models on ModelFold.
Core Capabilities of o3
Up to 200K tokens of context
Keep long conversations, large documents and sizeable code in a single request, so the model can reason over the full material instead of fragments.
Understands images and files (such as PDF)
Besides text, o3 accepts images and files (such as PDF) as input, so a single request can combine instructions with visual or other media.
Function calling
o3 supports tool (function) calling: describe your functions in the request and the model returns structured calls your code can run — the basis for agents and integrations.
Reasoning mode
o3 can produce reasoning before its final answer; in the Playground you can switch reasoning on or off to compare results.
Structured outputs
Ask for JSON that follows a schema (response_format), which makes extraction, classification and system integrations more reliable.
How to Use o3 on ModelFold
- 1
Step 1: Try it in the Playground
Open the Playground at the top of this page, type a prompt and see how o3 responds before writing any code.
- 2
Step 2: Create an API key
Sign in to ModelFold and create an API key in the console. Keep it secret and send it as a Bearer token.
- 3
Step 3: Send a request
Call POST https://modelfold.ai/v1/chat/completions with "model": "o3" and your messages. Existing OpenAI-compatible SDKs work by changing the base URL and key.
- ✓
Step 4: Ship and monitor
Integrate the response into your product and check token usage and spend for every call in the console logs.
What You Can Build with o3
Analysis and complex reasoning
Work through research questions, data interpretation, planning and other problems that need careful step-by-step reasoning.
AI coding assistants
Generate, explain, debug and refactor code, review pull requests and work through multi-file changes in developer tools and IDE plugins.
Screenshot and image understanding
Read screenshots, charts, diagrams and photos alongside text — for UI review, visual QA or turning images into structured data.
Writing and content
Draft, edit and translate articles, emails, product copy and documentation in a consistent tone.
Frequently Asked Questions
What is o3?⌄
o3 is a well-rounded, powerful OpenAI reasoning model for math, science, coding and visual reasoning, and it is also strong at technical writing and instruction following.
Which inputs does o3 support?⌄
o3 accepts text, images and files (such as PDF) and returns text. Through ModelFold you can send text and images (OpenAI-style image_url content); in the Playground you can also attach documents, which are converted to text.
How long is the context window of o3?⌄
Up to 200K tokens, shared between your input and the model’s output.
Does o3 support function calling?⌄
Yes. o3 supports tools / function calling through the standard tools parameter of the chat completions API.
How is o3 billed on ModelFold?⌄
Pay as you go by tokens: input and output tokens are charged at the per-million-token prices shown on this page. There is no monthly fee, and failed requests are not charged.
How do I call o3 through the API?⌄
Send a POST request to https://modelfold.ai/v1/chat/completions with "model": "o3", using your ModelFold API key as the Bearer token.
| Input | 400 credits 1M tokens≈ $2.00 |
| Output | 1600 credits 1M tokens≈ $8.00 |
Billed per token: input and output are priced separately, and thinking tokens count as output. The Playground charges exactly the same way.
Read API docs →AI Agents · Claude Code / Cursor / Trae →curl https://modelfold.ai/v1/chat/completions \
-H "Authorization: Bearer $MODELFOLD_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"o3","messages":[{"role":"user","content":"Hello"}]}'