OpenRouter launches GPT-5.5 Pro with inspectable reasoning tokens for agentic workflows

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OpenRouter integrated OpenAI's GPT-5.5 and GPT-5.5 Pro into its unified API, featuring a 1.05 million token context window. The Pro variant introduces a dedicated reasoning parameter that allows developers to monitor and preserve the model's internal thinking process during complex, multi-step tasks.

OpenRouter, a unified API for accessing hundreds of language models, added OpenAI's GPT-5.5 and GPT-5.5 Pro to its catalog. The Pro variant is optimized for high-stakes reasoning, featuring a 1.05 million token context window and a 128,000 token output limit for long-horizon problem solving.
Context window
1,050,000 tokens
Max output
128,000 tokens
Input price
$30.00 per million tokens
Output price
$180.00 per million tokens
Availability
OpenRouter API
Input types
Text and Image
Reasoning tokens
Supported via API parameter

This update follows recent frontier models like Xiaomi's MiMo-V2.5 with reasoning tokens. By exposing chain-of-thought steps through a reasoning parameter, developers can debug agentic loops, mirroring the focus on self-correction in OpenAI's GPT-5.5 launch for multi-step problem solving and long-horizon planning.

You can now integrate these models into production pipelines for agentic coding or document analysis, matching the industry shift seen in GitHub Copilot's GPT-5.5 rollout. Access is available via the OpenRouter API, with GPT-5.5 Pro priced at $30 per million input tokens and $180 per million output tokens.

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OpenAI's GPT-5.5 and GPT-5.5 Pro are live now on OpenRouter! GPT-5.5 is SOTA for long running work across code, data, and tools, with GPT-5.5 Pro for more complex reasoning and analysis. https://t.co/LR754ysHIA

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Still wondering? A few quick answers below.

GPT-5.5 Pro is OpenAI's high-capability model designed for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1.05 million token context window and is optimized for long-horizon problem solving, agentic coding, and precise execution across multi-step workflows. It supports both text and image inputs for multimodal analysis.

Pricing for GPT-5.5 Pro on OpenRouter is set at $30 per million input tokens and $180 per million output tokens. This pricing reflects its positioning as a frontier model for professional workloads. OpenRouter provides a unified API that routes requests to the best available providers while maintaining these standardized rates for users.

Reasoning tokens represent the model's internal step-by-step thinking process before it generates a final answer. Developers can enable this feature using a specific reasoning parameter in the API request. This allows users to access the model's internal deliberation through a reasoning details array, which is useful for debugging and steering complex agentic tasks.

GPT-5.5 Pro features a massive 1,050,000 token context window, which is split into approximately 922,000 input tokens and a maximum of 128,000 output tokens. This large window enables the model to process entire codebases, long documents, or complex multimodal data within a single interaction without losing track of the broader context.

While both models are designed for complex professional workloads, GPT-5.5 is positioned as the state-of-the-art standard for long-running work across code, data, and tools. GPT-5.5 Pro is a more advanced variant specifically optimized for deeper reasoning, higher accuracy in high-stakes scenarios, and more complex analysis compared to the standard GPT-5.5 model.

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