Cheap Claude Sonnet 5 API

What a top-up buys on Claude Sonnet 5

Output-token count only; input tokens are cheaper. First top-up is at least 2.5×.

When to pick Claude Sonnet 5

Claude Sonnet 5 costs $0.0080 per 1,500-in/500-out request at list price, $0.0040 effective. It sits in the mid price range — a good default for production apps.

Claude Sonnet 5 vs similarly priced models

Nearest models to Claude Sonnet 5 by blended price (3 input : 1 output). All run on one Somnus key.

Getting the most out of Claude Sonnet 5 for less

• Input is 5.0× cheaper than output on Claude Sonnet 5, so long context with short answers is the cheapest pattern.
• A $200 top-up gives $500 credit — about 125M blended Claude Sonnet 5 tokens.
• Mix models: send easy steps to DeepSeek V4 Flash and keep Claude Sonnet 5 for the steps that need it.

Other Claude models on Somnus

Every Anthropic model shares the same key and balance.

Use Claude Sonnet 5

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.SOMNUS_API_KEY,
  baseURL: "https://gateway-production-c837.up.railway.app/v1",
});

const resp = await client.chat.completions.create({
  model: "claude-sonnet-5",
  messages: [
    {"role": "user", "content": "Summarise this in one line"}
  ],
});
console.log(resp.choices[0].message.content);

Model id: "claude-sonnet-5".

Questions

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