GPT-5.4 vs Claude 4 Sonnet for Legal
Compare GPT-5.4 by OpenAI and Claude 4 Sonnet by Anthropic for legal tasks - pricing, context windows, and strengths, and see how to put either to work in Appaca.
GPT-5.4
OpenAI's frontier model for complex professional work with best intelligence at scale for agentic, coding, and professional workflows.
View GPT-5.4Claude 4 Sonnet
A balanced-hybrid reasoning model tuned for everyday assistant and high-volume tasks.
View Claude 4 SonnetGPT-5.4 vs Claude 4 Sonnet at a glance
Specs and pricing side by side, from the Appaca AI models directory.
| Spec | GPT-5.4 | Claude 4 Sonnet |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Model type | Text | Text |
| Context window | 1.05M tokens | 1M tokens |
| Input price | $2.5 / 1M tokens | $3 / 1M tokens |
| Output price | $15 / 1M tokens | $15 / 1M tokens |
| Status | Current | Superseded by Claude 4.5 Sonnet |
What matters for Legal
Evaluation criteria and how GPT-5.4 and Claude 4 Sonnet compare on what legal tasks actually require.
Precision and accuracy in legal language
Ability to identify risks and ambiguous clauses
Appropriate caveats and professional disclaimers
Handling long documents within context window
-
GPT-5.4 is 17% cheaper on input tokens ($2.5 vs $3 per million), which adds up quickly on high-volume legal workloads.
-
Context windows are close: GPT-5.4 handles 1.05M tokens and Claude 4 Sonnet handles 1M tokens.
-
Claude 4 Sonnet has been superseded by Claude 4.5 Sonnet - for new legal builds, consider the newer model first.
Strengths side by side
Where each model shines, according to benchmarks and provider positioning.
GPT-5.4
1. Best Intelligence at Scale
- OpenAI positions GPT-5.4 as its frontier model for agentic, coding, and professional workflows.
- Built for complex professional work where stronger reasoning and higher answer quality matter.
2. Configurable Reasoning + Multimodal Input
- Supports configurable reasoning effort from none to xhigh, letting teams balance speed and depth.
- Accepts both text and image inputs while producing text output.
3. Massive Context for Long-Running Work
- 1.05M token context window supports very large codebases, documents, and multi-step workflows.
- Allows up to 128 k output tokens for long-form answers and larger generations.
4. Updated Knowledge & Broad Tool Support
- Knowledge cut-off of Aug 31 2025 keeps it current for newer frameworks and business context.
- Supports tools like web search, file search, code interpreter, hosted shell, computer use, and MCP in the Responses API.
Claude 4 Sonnet
- Hybrid reasoning: supports both fast (“near-instant”) and extended thinking modes.
- Optimised for responsiveness, cost and high-volume production workloads.
- Strong coding performance relative to prior Sonnet versions (improved over Sonnet 3.7).
- Available even in free tiers (alongside paid plans).
- Better suited for general-purpose use and agents where speed + cost-efficiency matter.
Use GPT-5.4 or Claude 4 Sonnet - or both
Appaca is the AI workspace for operators. Build internal legal tools and AI co-workers powered by GPT-5.4 or Claude 4 Sonnet - 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 legal and it builds a working app powered by GPT-5.4 or Claude 4 Sonnet. No code, no API keys, no deployment.
Switch models without rebuilding
Start on GPT-5.4, test the same tool on Claude 4 Sonnet, and keep whichever performs better for your legal 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 legal and it builds a working app powered by GPT-5.4 or Claude 4 Sonnet - connected to the tools you already use.
Keep comparing for Legal
More side-by-side model comparisons for legal tasks.
FAQs
Claude 4 Opus and GPT-5.5 are the top legal LLMs in 2026. Claude 4 Opus excels at identifying ambiguous clauses, drafting precise contract language, and handling nuanced legal reasoning with appropriate disclaimers. GPT-5.5 is preferred for structured document output and legal research synthesis. Both offer the large context windows needed for full contract review.
GPT-5.4 is generally cheaper: $2.5 input / $15 output per million tokens, versus $3 / $15 for Claude 4 Sonnet. Actual cost depends on how many tokens your legal workload reads and writes.
GPT-5.4 has the larger context window at 1.05M tokens, compared to 1M tokens for Claude 4 Sonnet. For legal 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 legal and the Appaca agent builds it as a working app powered by GPT-5.4, Claude 4 Sonnet, 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 Legal tools with GPT-5.4 or Claude 4 Sonnet
Describe the legal 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.