claude-sonnet-4-5-20250929 · claude-sonnet-5-5Both Claude Sonnet 4.5 (20250929) and Claude Sonnet 5.5 are accessible through a single Newton’s API key using standard OpenAI SDKs.
Live per-million-token pricing served through Newton’s unified OpenAI-compatible gateway.
| Metric | Anthropic: Claude Sonnet 4.5 (20250929) | Anthropic: Claude Sonnet 5.5 |
|---|---|---|
| API Model ID | claude-sonnet-4-5-20250929 | claude-sonnet-5-5 |
| Provider Lab | Anthropic | Anthropic |
| Gateway Status | Catalog | Available |
| Input / 1M tokens | — | $0.20 |
| Cached Input / 1M tokens | — | $0.01 |
| Output / 1M tokens | — | $1.00 |
| Context Window | 128K+ | 128K+ |
Estimated spend for typical coding and autonomous agent workloads based on published per-token rates:
Because Newton’s exposes both claude-sonnet-4-5-20250929 and claude-sonnet-5-5 behind the same API key and base URL, engineering teams frequently combine both models in the same workflow:
Point the official OpenAI SDK, Cursor, or Claude Code at https://newtons.dev/api/v1 and swap the model string on demand:
import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.NEWTONS_API_KEY,
baseURL: "https://newtons.dev/api/v1",
});
// Switch between Claude Sonnet 4.5 (20250929) and Claude Sonnet 5.5 with 1 line:
const response = await client.chat.completions.create({
model: "claude-sonnet-4-5-20250929", // or "claude-sonnet-5-5"
messages: [{ role: "user", content: "Compare architecture trade-offs." }],
});