GPT OSS 120B vs Claude Opus 5.5
Compare GPT OSS 120B and Claude Opus 5.5 side-by-side. See comparisons of price, response speed, accuracy, and file support to choose the best model for your task.
Overview
GPT OSS 120B vs Claude Opus 5.5 Overview
Everything you need to know about these AI models, including capabilities, performance, pricing, and technical details.
OpenAI / GPT OSS 120B
lightDescription
OpenAI's open-weight reasoning model, and its first open release since GPT-2. GPT OSS 120B is built for agentic work, tool use, and configurable reasoning, activating only a small fraction of its parameters per token, thereby running efficiently. It exposes its full chain of thought, which most closed models hide. Text only, with a moderate context window. Apache 2.0 licensed, so the weights are public and freely deployable. Free to start on Aymo.
Anthropic / Claude Opus 5.5
maxDescription
Anthropic's newest flagship, and the first in its Claude 5.5 family. Anthropic positions Opus 5.5 to perform at the level of its most capable model on most work, while costing meaningfully less to run than the previous Opus. It reads text and images, holds a very large context, and reasons before every answer with adjustable effort. Anthropic calls it their daily driver for serious coding, computer use, and knowledge work, with its knowledge current to mid-2026.
About
About
Capabilities
Capabilities
Comparison
Why Use GPT OSS 120B and Claude Opus 5.5?
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OpenAI / GPT OSS 120B
lightAgentic Coding And Tools
OpenAI built it for agentic workflows with strong instruction following and native tool use, including web search and Python execution. Suited to multi-step development work rather than the hardest frontier engineering.
Reasoning
Configurable reasoning at low, medium, and high effort, with full chain-of-thought exposed rather than hidden. You can follow how it reached an answer, which helps debugging and trust. OpenAI reports it near o4-mini on core reasoning.
A Moderate Context Window
Handles a moderate context window, roughly 96,000 words. Enough for long documents, multi-turn conversations, and substantial codebases, though well short of the million-token frontier models.
Structured Output
Supports structured outputs and a JSON schema, so it slots into applications and agent pipelines rather than only chat. Built for developer workflows that need predictable, parseable responses.
Analysis Through Tools
Reasons for what you supply, and you can browse or run code when tools are connected. It has no built-in knowledge of current events beyond training, so live data comes through the tools you attach.
Text Only Input
Reads and writes text. No image, audio, or video input. Screenshots, diagrams, and scanned pages are outside what it reads, so it works only from text and code.
Anthropic / Claude Opus 5.5
maxDaily-Driver Coding
Anthropic positions it as its everyday model for serious coding and agentic work, reaching its most capable model's level on most tasks. Built for real software engineering across many steps rather than isolated snippets.
Adaptive Thinking Always On
Reasoning is always on, with an effort dial rather than an off switch, defaulting to medium. Anthropic reports medium effort here, matching the previous Opus at high, so it thinks efficiently rather than at length.
Room For Whole Projects
A very large context window with no smaller default. Anthropic reports stronger long-context management, so instruction following and reasoning hold across a full codebase or a long agent run.
Precise Document Work
Anthropic's strongest Opus for vision and document work: dense filings, charts, screenshots, and diagrams read at high fidelity. It also writes more concisely than the previous Opus, a deliberate change.
Deep Computer Use
Anthropic reports that its best Opus is for computer use, handling multi-step tasks that span several applications and require planning and judgment. Suited to agentic work that operates real software, not just answering questions.
Text And Image Input
Reads text, images, and PDFs in the same prompt, so you can send screenshots, filings, diagrams, or charts alongside your question. Output is text only. Audio and video are not accepted.
Why Aymo
Why chat with GPT OSS 120B and Claude Opus 5.5 on Aymo AI?
Aymo gives you more than access to GPT OSS 120B and Claude Opus 5.5—it provides a complete multi-model AI workspace designed for productivity.
Compare Responses
See how GPT OSS 120B and Claude Opus 5.5 performs alongside Claude, Gemini, Grok, and other leading AI models.
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