GPT-5.5 vs Claude 4 Opus for Writing
Compare GPT-5.5 by OpenAI and Claude 4 Opus by Anthropic for writing tasks - pricing, context windows, and strengths, and see how to put either to work in Appaca.
GPT-5.5
OpenAI's smartest and most capable model yet for agentic coding, knowledge work, and computer use, delivering a new class of intelligence at GPT-5.4 latency.
View GPT-5.5Claude 4 Opus
The flagship model, focused on deep reasoning, large-scale coding and sustained multi-step agentic workflows.
View Claude 4 OpusGPT-5.5 vs Claude 4 Opus at a glance
Specs and pricing side by side, from the Appaca AI models directory.
| Spec | GPT-5.5 | Claude 4 Opus |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Model type | Text | Text |
| Context window | 1M tokens | 200K tokens |
| Input price | $5 / 1M tokens | $15 / 1M tokens |
| Output price | $30 / 1M tokens | $75 / 1M tokens |
| Status | Current | Superseded by Claude 4.1 Opus |
What matters for Writing
Evaluation criteria and how GPT-5.5 and Claude 4 Opus compare on what writing tasks actually require.
Fluency and natural prose quality
Adherence to tone, style, and formatting instructions
Creativity and originality in content generation
Ability to follow detailed writing briefs
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GPT-5.5 is 67% cheaper on input tokens ($5 vs $15 per million), which adds up quickly on high-volume writing workloads.
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GPT-5.5 is 60% cheaper on output tokens ($30 vs $75 per million) - the bigger factor for writing tasks that generate long responses.
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GPT-5.5's 1M tokens context window is roughly 5x larger than Claude 4 Opus's 200K tokens, so it can handle bigger inputs in a single writing pass.
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Claude 4 Opus has been superseded by Claude 4.1 Opus - for new writing builds, consider the newer model first.
Strengths side by side
Where each model shines, according to benchmarks and provider positioning.
GPT-5.5
1. Strongest Agentic Coding Model
- State-of-the-art on Terminal-Bench 2.0 (82.7%), Expert-SWE (73.1%), and SWE-Bench Pro (58.6%), outperforming GPT-5.4 on complex coding tasks.
- Holds context across large systems, reasons through ambiguous failures, and carries changes through surrounding codebases with fewer tokens.
2. Higher Intelligence at GPT-5.4 Latency
- Co-designed, trained, and served on NVIDIA GB200/GB300 NVL72 systems to match GPT-5.4 per-token latency while performing at a significantly higher level.
- Uses fewer tokens to complete the same tasks, making it more efficient as well as more capable.
3. Powerful for Knowledge Work & Computer Use
- Scores 84.9% on GDPval (44 occupations) and 78.7% on OSWorld-Verified for autonomous computer operation.
- Excels at generating documents, spreadsheets, and reports; naturally moves across finding information, using tools, and checking output.
4. Scientific Research Co-Scientist
- Leading performance on GeneBench, BixBench, and FrontierMath; helped discover a new proof about Ramsey numbers verified in Lean.
- Strong enough to meaningfully accelerate progress at the frontiers of biomedical and mathematical research.
Claude 4 Opus
- Highest capability in the family: described as “our most powerful model yet” by Anthropic.
- Exceptional at long-running tasks requiring thousands of steps and sustained focus (e.g., continuous codebase work for hours).
- Excellent performance on benchmarks: e.g., SWE-bench 72.5 % and Terminal-bench 43.2 %.
- Designed for complex agentic workflows, deep reasoning, tool use, and large context windows.
- Placed under a higher safety classification (ASL-3) due to its frontier capability and risk profile.
Use GPT-5.5 or Claude 4 Opus - or both
Appaca is the AI workspace for operators. Build internal writing tools and AI co-workers powered by GPT-5.5 or Claude 4 Opus - connected to your real data and ready for your whole team. No code, no deployment.
Describe it, and it's built
Tell the Appaca agent the internal tool you need for writing and it builds a working app powered by GPT-5.5 or Claude 4 Opus. No code, no API keys, no deployment.
Switch models without rebuilding
Start on GPT-5.5, test the same tool on Claude 4 Opus, and keep whichever performs better for your writing workflow - the rest of your app stays exactly as it is.
Automated for the whole team
Schedule tools to run on autopilot - daily digests, weekly reports, real-time triggers - and share them with your whole team from one workspace.
Describe it, and it's built
Tell the Appaca agent what your team needs for writing and it builds a working app powered by GPT-5.5 or Claude 4 Opus - connected to the tools you already use.
Keep comparing for Writing
More side-by-side model comparisons for writing tasks.
FAQs
GPT-5.5 and Claude 4 Opus lead for writing quality in 2026. GPT-5.5 excels at structured, persuasive content and SEO-aware formatting. Claude 4 Opus produces the most natural, creative prose - with fewer clichés and stronger voice consistency - making it the preferred choice for long-form articles, essays, and narrative content.
GPT-5.5 is generally cheaper: $5 input / $30 output per million tokens, versus $15 / $75 for Claude 4 Opus. Actual cost depends on how many tokens your writing workload reads and writes.
GPT-5.5 has the larger context window at 1M tokens, compared to 200K tokens for Claude 4 Opus. For writing tasks, a larger window means the model can consider more context at once without losing track.
Yes. Appaca is a no-code AI workspace: describe the internal tool your team needs for writing and the Appaca agent builds it as a working app powered by GPT-5.5, Claude 4 Opus, or any other model in the directory - with a built-in database, team access, and integrations. No API keys to wire up and nothing to deploy.
Build Writing tools with GPT-5.5 or Claude 4 Opus
Describe the writing tool your team needs and get a working app powered by the model you choose - with a built-in database, team access, and integrations. No code, no deployment.