Question 1

What is Claude Sonnet 4?

Accepted Answer

Claude Sonnet 4 is a model from Anthropic, released on May 22, 2025. Claude Sonnet 4 significantly enhances the capabilities of its predecessor, Sonnet 3.7, excelling in both coding and reasoning tasks with improved precision and controllability. Achieving state-of-the-art performance on SWE-bench (72.7%), Sonnet 4 balances capability and computational efficiency, making it suitable for a broad range of applications from routine coding tasks to complex software development projects. Key enhancements include improved autonomous codebase navigation, reduced error rates in agent-driven workflows, and increased reliability in following intricate instructions. Sonnet 4 is optimized for practical everyday use, providing advanced reasoning capabilities while maintaining efficiency and responsiveness in diverse internal and external scenarios. Read more at the blog post here.

Question 2

How much does Claude Sonnet 4 cost?

Accepted Answer

On the Respan gateway, input starts at $3.00 per 1M tokens on OpenRouter, and output starts at $15.00 per 1M tokens on OpenRouter, after gateway discounts.

Question 3

Which providers serve Claude Sonnet 4 on Respan?

Accepted Answer

Claude Sonnet 4 is served by OpenRouter.

Question 4

What is Claude Sonnet 4's context window?

Accepted Answer

Claude Sonnet 4 accepts up to 200K tokens of context.

Question 5

How do I use Claude Sonnet 4 with the Respan gateway?

Accepted Answer

Point any OpenAI-compatible SDK at https://api.respan.ai/api/ with your Respan API key and set the model to "claude-sonnet-4". To set it up with a coding agent, copy the agent setup prompt at the top of this page.

Question 6

How fast is Claude Sonnet 4?

Accepted Answer

Over the last 30 days of requests through the Respan gateway, the fastest provider was OpenRouter at 25 tokens per second, and the lowest response latency was 0.8 seconds on OpenRouter. Speed varies with request size and provider.

Question 7

Where does Claude Sonnet 4 rank on the Respan Index?

Accepted Answer

Claude Sonnet 4 scores 18.7 out of 100 on the Respan Index v1.1, ranking #99 of 138 models. By category: Coding 8.4, Agents 18.2, Reasoning 14.0, Knowledge & language 17.7 (estimated), and Human preference 44.9. The Respan Index combines independent and lab-reported benchmark results into one score, using benchmark data collected by llmmetric.com.

Question 8

How does Claude Sonnet 4 score on benchmarks?

Accepted Answer

Claude Sonnet 4 has 12 published benchmark scores, including SWE-bench Verified 72.7%, OSWorld-Verified 41.4%, and GPQA Diamond 79.2%. Each score links to where it was published; the data is collected by llmmetric.com.

Claude Sonnet 4

Providers

Certified where it counts.

Pricing

Cost by volume

Throughput and latency

Output speed

Response latency

Benchmarks

Respan Indexv1.1

Coding3

Apps

Claude Sonnet 4 FAQ

Works with your entire stack

Built for AI agents.
Break less.
Ship more.

Agents1

Reasoning2

Math3

Arena2

Other1