GPT-5.5 vs Claude Fable 5.1
Compare GPT-5.5 and Claude Fable 5.1 side-by-side. See comparisons of price, response speed, accuracy, and file support to choose the best model for your task.
Overview
GPT-5.5 vs Claude Fable 5.1 Overview
Everything you need to know about these AI models, including capabilities, performance, pricing, and technical details.
OpenAI / GPT-5.5
maxDescription
OpenAI's frontier model is built for complex professional work. GPT-5.5 takes on demanding coding, deep reasoning, and analysis across very large inputs. It reads text and images, searches the web for current information, and lets you dial its reasoning effort up or down depending on how hard the problem is. Priced at the premium end of OpenAI's range, and built to earn it.
Anthropic / Claude Fable 5.1
maxDescription
Anthropic's most capable generally available model, sitting above the Opus line. Fable 5.1 is built for long, unsupervised work: multi-day coding, agentic research, and tasks that run across dozens of tool calls. It reads text and images, maintains a very large context, and reasons before every answer at an adjustable depth. Its knowledge is the most recent of any Claude model. Anthropic positions Opus 5 as the starting point for most work, and Fable 5.1 for teams whose evaluations demand a higher ceiling.
About
About
Capabilities
Capabilities
Comparison
Why Use GPT-5.5 and Claude Fable 5.1?
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OpenAI / GPT-5.5
maxFrontier-Level Coding
OpenAI positions this as its model for the most complex professional work, with coding as the headline use. Handles large codebases, multi-step engineering tasks, and production-quality output.
Highest-Rated Reasoning
OpenAI's own model documentation rates its reasoning Highest, the top of the scale. Reasoning tokens are supported, so the model thinks before it answers, and you control how much thinking it does.
Large Context Window
1,050,000 tokens, among the largest available anywhere. Load an entire codebase, a full research corpus, or a large document set and ask questions across all of it. Prompts above 272,000 input tokens are billed at a higher rate.
Long-Form Professional Writing
Built for output that ships, not quick drafts. Writes up to 128,000 tokens in a single response, which covers long reports, full documentation sets, and extended technical writing without splitting the job up.
Live Web Research
Web search is a supported tool, so it can pull current information into an answer rather than working only from what it was trained on. Its knowledge cutoff is 1 December 2025, so anything more recent needs that search.
Text & Image Input
Reads text and images. OpenAI's documentation lists image as input-only and states that audio and video are not supported. File search is supported, so it can work across uploaded documents.
Anthropic / Claude Fable 5.1
maxLong-Running Coding
Anthropic's strongest model for multi-day coding sessions and codebase research. Built to sustain complex software engineering across many steps and tool calls without a human checking in at each one.
Adaptive Thinking Always On
Reasoning is always on, with adjustable effort rather than an on-off switch. Steer depth up for the hardest problems or down for lighter work, without restructuring the prompt each time.
Room For Whole Projects
A very large context window, among the largest available. Load an entire codebase, a long research corpus, or a large document set and work across all of it in a single session.
Document-Heavy Analysis
Built for document-heavy analysis and multi-step automation alongside coding. Suited to work that reads across large, mixed source material and produces structured, reviewable output.
Long-Horizon Agent Work
Its defining strength. Retains context, uses tools, evaluates results, and works on a task through many steps. Built for agents who run for a long time with little supervision.
Text And Image Input
Reads text and images in the same prompt, so you can send screenshots, diagrams, or scanned pages alongside your question. Output is text only. Audio and video are not accepted.
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Why chat with GPT-5.5 and Claude Fable 5.1 on Aymo AI?
Aymo gives you more than access to GPT-5.5 and Claude Fable 5.1—it provides a complete multi-model AI workspace designed for productivity.
Compare Responses
See how GPT-5.5 and Claude Fable 5.1 performs alongside Claude, Gemini, Grok, and other leading AI models.
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