Gemini 3.5 Flash vs Sonar Reasoning Pro: side-by-side summary

Gemini 3.5 Flash and Sonar Reasoning Pro are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

Gemini 3.5 Flash, from Google, has a 1,048,576-token context window and is priced at $1.50/M tokens input, $9/M tokens output on OpenRouter.

Sonar Reasoning Pro, from Perplexity, has a 128,000-token context window and is priced at $2/M tokens input, $8/M tokens output on OpenRouter.

Context window

• Gemini 3.5 Flash: 1,048,576 tokens
• Sonar Reasoning Pro: 128,000 tokens

Price

• Gemini 3.5 Flash: $1.50/M tokens input, $9/M tokens output
• Sonar Reasoning Pro: $2/M tokens input, $8/M tokens output

Provided by

• Gemini 3.5 Flash: Google
• Sonar Reasoning Pro: Perplexity

• Gemini 3.5 Flash model details, providers and pricing
• Sonar Reasoning Pro model details, providers and pricing