OpenAI · o-series · Legacy

o1

The first reasoning model — historically important, now superseded.

The o1 model, part of the OpenAI o-series, is a high-performance AI designed for a broad range of tasks, supporting text, image, and file modalities. Its standout feature is a 200,000-token context window, enabling it to manage long sequences with strong coherence and contextual understanding.

With multimodal capabilities and extensive context handling, the o1 model is tailored for developers and product teams tackling complex applications, including natural language processing, content creation, code development, and data analysis.

The o1 model occupies a prominent role in the o-series lineup, combining an advanced 200,000-token context window with multimodal functionalities. These capabilities represent a significant leap from earlier models, making the o1 suitable for tasks requiring rich data integration and sustained contextual comprehension.

Background

OpenAI o1 is a generative pre-trained transformer (GPT), the first in OpenAI's "o" series of reasoning models. A preview of o1 was released by OpenAI on September 12, 2024. o1 spends time "thinking" before it answers, making it better at complex reasoning tasks, science and programming than GPT-4o. The full version was released to ChatGPT users on December 5, 2024.

Wikipedia

Specs

Context window: 200K tokens
Max output: 100K tokens
Input ($/1M tokens): $15.00
Output ($/1M tokens): $60.00
Modalities: Text · Image · File
Released: Dec 5, 2024
Weights: Closed

Pricing last synced Apr 27, 2026 via OpenRouter. Confirm against official docs before committing.

Capabilities

Tool use
Vision
Extended thinking
Prompt caching
Open weights

What it excels at

Long context handling
Supports up to 200,000 tokens, ideal for extensive input or output sequences.
Multimodal capabilities
Processes and generates text, images, and files for diverse applications.
Advanced text generation
Produces coherent, contextually accurate text across long-form content.
Scalable performance
Handles large-scale tasks consistently, suitable for real-time workflows.

When to use this model

→Analyzing lengthy documents — The large context window enables efficient and detailed document processing.
→Automating design workflows — Multimodal input support allows seamless text and image asset handling.
→Content creation and summarization — Generates and condenses long-form text effectively.
→Research and data processing — Handles extensive datasets to provide deep analytical insights.
→Building conversational AI — Maintains context and coherence over extended conversations.

Analysis synthesized from gpt-4o, llama-4-maverick, phi-4, etc.

API model id

Vendor docs: platform.openai.com/docs

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