Claude Sonnet 5.5 API: rates and integration example

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Published: Oct 24, 2026, 3:47 AM UTC · Updated: Oct 24, 2026, 3:47 AM UTC

Exact ID: claude-sonnet-5-5. Check access for your key using GET /v1/models; a published model does not guarantee access for every account.

Prices and billing units

Workload budget: input and output

Specifications and compatibility boundaries

The manufacturer specifies a context window of 1,000,000 and a maximum output of 128,000 tokens for its own API (specification: Anthropic, checked Oct 24, 2026). These are not verified effective API429 limits: the current public catalog does not publish them. Confirm the required volume and mode before migrating your workload.

API429 capabilities published for this exact ID: chat function_calling reasoning structured_output vision . A missing property does not mean a prohibition, but it does not establish support. Check input format, tools, JSON/schema, reasoning and streaming separately for the selected method.

Public model observations

Over the last 24 hours: mean successful response time — 6.2 s; service error rate — 0%. Data as of Oct 24, 2026, 5:38 AM UTC.

Source: public 24-hour statistics. The mean is neither a median nor a response time guarantee; the error rate and observation window refer to the API429 service. Model quality is not measured here.

First request: curl, Python, JavaScript

Create a key, check your balance and set API429_API_KEY on the server. The generation example incurs a charge. It does not retry automatically; a timeout does not prove the operation was not charged. Inspect the content and actual usage after receiving a response. Python and JavaScript first check the available model list.

curl

Before generation, check the exact ID in the response from GET https://gateway.api429.com/v1/models using the same Bearer key.

curl --fail-with-body https://gateway.api429.com/v1/chat/completions \
  -H "Authorization: Bearer $API429_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-sonnet-5-5","messages":[{"role":"user","content":"For the task “add CSV export”, suggest a brief implementation plan and three verifiable acceptance criteria. Do not perform any actions."}],"max_tokens":512,"stream":false}'

Python 3

import json
import os
import urllib.request

key = os.environ["API429_API_KEY"]
base = "https://gateway.api429.com/v1"
headers = {"Authorization": "Bearer " + key, "Content-Type": "application/json"}
models_request = urllib.request.Request(base + "/models", headers=headers)
with urllib.request.urlopen(models_request, timeout=30) as response:
    available = {item["id"] for item in json.load(response)["data"]}
model = "claude-sonnet-5-5"
if model not in available:
    raise ValueError("Model is unavailable to this key")
payload = json.loads("{\"model\":\"claude-sonnet-5-5\",\"messages\":[{\"role\":\"user\",\"content\":\"For the task “add CSV export”, suggest a brief implementation plan and three verifiable acceptance criteria. Do not perform any actions.\"}],\"max_tokens\":512,\"stream\":false}")
request = urllib.request.Request(base + "/chat/completions",
    data=json.dumps(payload).encode("utf-8"), headers=headers, method="POST")
with urllib.request.urlopen(request, timeout=60) as response:
    result = json.load(response)
choice = result["choices"][0]
if choice.get("finish_reason") != "stop" or not choice.get("message", {}).get("content"):
    raise ValueError("Incomplete or empty response")
print(choice["message"]["content"])
print(result.get("usage"))

JavaScript: Node.js 18+

const key = process.env.API429_API_KEY;
if (!key) throw new Error("Set API429_API_KEY");
const base = "https://gateway.api429.com/v1";
const headers = { Authorization: "Bearer " + key, "Content-Type": "application/json" };
const model = "claude-sonnet-5-5";
const available = await fetch(base + "/models", { headers, signal: AbortSignal.timeout(30000) });
if (!available.ok) throw new Error("Models HTTP " + available.status);
if (!(await available.json()).data.some(item => item.id === model)) throw new Error("Model unavailable to this key");
const response = await fetch(base + "/chat/completions", {
  method: "POST", headers, signal: AbortSignal.timeout(60000),
  body: JSON.stringify({"model":"claude-sonnet-5-5","messages":[{"role":"user","content":"For the task “add CSV export”, suggest a brief implementation plan and three verifiable acceptance criteria. Do not perform any actions."}],"max_tokens":512,"stream":false})
});
if (!response.ok) throw new Error("Generation HTTP " + response.status);
const result = await response.json();
const choice = result.choices?.[0];
if (choice?.finish_reason !== "stop" || !choice?.message?.content) throw new Error("Incomplete or empty response");
console.log(choice.message.content);
console.log(result.usage);

The examples use basic fields from the published API contract. They are checked offline; no successful paid execution or output accuracy is claimed.

n8n: minimal HTTP Request

1. Create an HTTP Request with method POST and URL https://gateway.api429.com/v1/chat/completions.
2. Store the Bearer key in credentials; add Content-Type: application/json. Do not put the key in an exported workflow example.
3. Send the JSON from curl: the exact model claude-sonnet-5-5, messages, max_tokens and stream=false.
4. After the HTTP node, check choices, finish_reason and the response content before writing the result to your production system.

HTTP Request documentation. This recipe describes HTTP Request. Compatibility with specific Agent nodes, SDKs and other API methods needs separate verification.

Three models for your own comparison

These are options for a controlled comparison on the same task, rather than a quality ranking. Base rates apply to a short text request; see the catalog for full pricing.

Version and release date

Manufacturer API release date, Anthropic: Sep 28, 2026. Previous generation: Claude Sonnet 5; this does not automatically replace the ID in your integration. The date of addition to API429 is unknown. Current availability is determined by the catalog and key permissions, rather than the manufacturer’s historical release date.

Frequently asked questions

Sources and review

• platform.claude.com/docs/en/models/sonnet-5-5/overview
• platform.claude.com/docs/en/models/sonnet-5-5/whats-new-sonnet-5-5
• gateway.api429.com/api/public/openapi.json
• docs.n8n.io/integrations/builtin/core-nodes/n8n-nodes-base.httprequest/

Editorial review: Oct 23, 2026, 10:02 PM UTC. Pricing and general calculator · Getting started · Compare the family: Claude