Claude 4.0 Sonnet (API)

The new standard for enterprise AI. The Claude 4.0 Sonnet API delivers hybrid reasoning capabilities, enabling developers to toggle between instant responses and extended thinking for complex workflows.

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Claude 4.0 Sonnet API — Intelligent Hybrid Reasoning

Deploy the Claude 4.0 Sonnet API to build agents that think before they act. Achieve Opus-level logic at mid-tier latency with the new extended thinking mode.

What can you build with the Claude 4.0 Sonnet API?

Agentic customer support

Create empathetic, context-aware bots using the Claude 4.0 Sonnet API. Handle multi-turn queries with reduced latency.

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Data extraction pipelines

Turn unstructured documents into deterministic JSON. The API excels at complex schema adherence for automated reporting.

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Coding & dev assistants

Leverage state-of-the-art coding logic. Claude 4.0 Sonnet powers background bug-fixing and multi-file architecture planning.

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Why developers choose the Claude 4.0 Sonnet API

The definitive balance of cost, speed, and 'extended thinking' intelligence for scaled applications.

Hybrid Reasoning

Dynamically switch the Claude 4.0 Sonnet API between fast chat and deep 'extended thinking' modes.

Parallel Tool Use

Execute multiple API calls simultaneously, drastically reducing wait times for complex agent tasks.

Enterprise Safety

Built on Anthropic's Constitutional AI, ensuring safe, brand-aligned outputs for production.

How to integrate the Claude 4.0 Sonnet API

From API key to production-ready agent in three steps.

Step 1 — Configure Context

Initialize the Claude 4.0 Sonnet API with system prompts and relevant retrieval (RAG) data chunks.

Step 2 — Enable Tools

Define function definitions or JSON schemas. Enable 'extended thinking' if the task requires deep planning.

Step 3 — Execute & Cache

Run your prompts. Use prompt caching to reduce latency and costs by up to 90% for repetitive contexts.

Open API Playground

Key Capabilities of Sonnet 4.0

Engineered for the next generation of AI apps

Context

Extended Context

Process vast amounts of data (200k+) seamlessly.

Tools

Robust Tool Use

Reliable function calling for complex orchestrations.

Cost

Competitive Pricing

$3/$15 pricing makes the Claude 4.0 Sonnet API scalable.

Speed

Low Latency

Faster time-to-first-token compared to Opus models.

Safety

Safety Filters

Enterprise-grade guardrails against jailbreaks.

Language

Multilingual Mastery

Native fluency in major languages for global apps.

Claude 4.0 Sonnet vs. The Claude Family

Select the right intelligence level for your workload

Model	Duration	Resolution	Price	Strength
Claude 4.0 Sonnet	N/A	Hybrid	Mid-tier	Balanced reasoning, extended thinking, best for agents.
Claude 4.1 Opus	N/A	Deepest	Premium	Maximum reasoning depth for scientific research.
Claude 4.5 Haiku	N/A	Fast	Economy	Lowest latency for high-volume simple tasks.

Frequently Asked Questions

Everything you need to know about the product and billing.

The main upgrade is 'Hybrid Reasoning,' allowing the model to pause and think deeply for complex tasks, or respond instantly for simple chat, all controllable via API.

It maintains mid-tier pricing (approx. $3 input / $15 output per million tokens), making it significantly cheaper than Opus 4.1.

Yes, the Claude 4.0 Sonnet API allows agents to invoke multiple tools at once, speeding up complex workflows.

Yes, prompt caching is supported, helping developers save on costs and reduce latency for static context data.

Absolutely. It is optimized for coding and architecture planning, often outperforming previous generations in bug detection.

The model supports a 200k token context window, perfect for analyzing large documents or maintaining long conversation history.

Haiku is faster and cheaper for simple tasks, while the Claude 4.0 Sonnet API offers superior reasoning and logic for complex applications.