Question 1

What is Claude Sonnet 5.5?

Accepted Answer

Claude Sonnet 5.5 is a model from Anthropic, released on Sep 28, 2026. Claude Sonnet 5.5 is Anthropic's model offering the best combination of speed and intelligence, with a 1M-token context window, 128K max output, and adaptive thinking.

Question 2

How much does Claude Sonnet 5.5 cost?

Accepted Answer

On the Respan gateway, input starts at $2.00 per 1M tokens on every provider, and output starts at $10.00 per 1M tokens on every provider, after gateway discounts.

Question 3

Which providers serve Claude Sonnet 5.5 on Respan?

Accepted Answer

5 providers serve Claude Sonnet 5.5: Anthropic, DeepInfra, OpenRouter, Perplexity, and Google Vertex AI. Perplexity and Google Vertex AI require your own provider API key (BYOK).

Question 4

What is Claude Sonnet 5.5's context window?

Accepted Answer

Claude Sonnet 5.5 accepts up to 1M tokens of context on its largest provider route.

Question 5

How do I use Claude Sonnet 5.5 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 "anthropic/claude-sonnet-5-5". 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 5.5?

Accepted Answer

Over the last 30 days of requests through the Respan gateway, the fastest provider was Anthropic at 10 tokens per second, and the lowest response latency was 1.0 seconds on Anthropic. Speed varies with request size and provider.

Question 7

Where does Claude Sonnet 5.5 rank on the Respan Index?

Accepted Answer

Claude Sonnet 5.5 scores 68.5 out of 100 on the Respan Index v1.1, ranking #6 of 138 models. By category: Coding 70.1, Agents 78.1, Reasoning 70.7, Knowledge & language 48.4, and Human preference 59.5. 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 5.5 score on benchmarks?

Accepted Answer

Claude Sonnet 5.5 has 29 published benchmark scores, including LiveBench Coding 91.4%, OSWorld 2.1 (partial) 80.1%, and GPQA Diamond 95.6%. Each score links to where it was published; the data is collected by llmmetric.com.

Provider	Context	Input	Output
Anthropic`anthropic/claude-sonnet-5-5`	1M	$2.00/M	$10.00/M
DeepInfra`deepinfra/anthropic/claude-sonnet-5-5`	1M	$2.00/M	$10.00/M
OpenRouter`openrouter/anthropic/claude-sonnet-5.5`	1M	$2.00/M	$10.00/M
PerplexityBYOK only`perplexity/anthropic/claude-sonnet-5-5`	1M	$2.00/M	$10.00/M
Google Vertex AIBYOK only`vertex_ai/claude-sonnet-5-5@default`	1M	$2.00/M	$10.00/M

Claude Sonnet 5.5

Providers

Certified where it counts.

Pricing

Cost by volume

Throughput and latency

Output speed

Response latency

Benchmarks

Respan Indexv1.1

Coding6

Apps

Claude Sonnet 5.5 FAQ

Works with your entire stack

Built for AI agents.
Break less.
Ship more.

Agents3

Reasoning6

Math4

Knowledge3

Multimodal2

Arena4

Other1