Claude Sonnet 5 - AI Model API and Pricing

Long-form writing with a voice that holds

Sonnet 5 is listed with the best style in longer forms. It holds a brand voice across many paragraphs. That matters for editorial articles, about pages, homepage sections and chapter-length drafts. In those, weaker models start to repeat themselves or drift into a generic tone halfway through.

The trade-off is price. Its listed limit is a higher rate, so you spend more per word than with the light models. Use it where the reader will notice the writing.

Article Generator or Ebook Generator

In the AI Article Generator, pick SEO article or Blog post for web content. Newsletter suits a longer issue, and Product description fits a flagship item that deserves a crafted page. Ad copy and Video script work too, though cheaper models cover short pieces well. The AI Ebook Generator has no presets and suits multi-chapter guides and lead magnets. Neither tool takes uploads, so paste your brand notes into the prompt.

Example prompts: "Write a 1,200-word feature on why small coffee roasters publish their sourcing. Tone: curious, dry humor, no jargon. Open with a scene." Or "Homepage hero and three sections for an accounting app for freelancers. Voice: calm, direct, a little warm."

Feeding it a brand voice

The engine reads only your prompt. Put a short voice guide at the top. Name the reader, give three words for the tone, and add a sentence you like and one you hate. The tool caps each response at a fixed length, so a very long piece can stop short. Ask for an outline first, approve it, then request the full draft section by section.

Credits for a typical piece

An 800-word blog post rounds up to 1k words and costs 16 credits, about $0.17 at the best pack. A 2,000-word article costs 32 credits, about $0.34. It ranks No. 8 from the cheapest of 10 text models, which span 1 to 47 credits per 1k words.

Picking against GPT-5.5, Gemini 2.5 Pro and Haiku

GPT-5.5 costs 47 credits per 1k words and has the best brief adherence. It is listed for copy that needs little editing before it goes to a client. Gemini 2.5 Pro sits at the same 16 credits. It is stronger when you write from long documents and research. Claude Haiku 4.5 costs 8 credits and is the sensible choice for captions, headlines and ad variants.

Where to actually run it

Claude Sonnet 5 API

curl -X POST https://ugesi.com/api/generate \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5",
    "prompt": "a product shot on white marble"
  }'

<?php
$ch = curl_init('https://ugesi.com/api/generate');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer YOUR_API_KEY',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode([
        'model' => 'claude-sonnet-5',
        'prompt' => 'a product shot on white marble',
    ]),
]);
$response = json_decode(curl_exec($ch), true);
curl_close($ch);
print_r($response);

type GenerateRequest = {
  model: string;
  prompt: string;
};
type GenerateResponse = {
  job_id: number;
  job_token: string;
  credits_held: number;
  status: "queued" | "succeeded";
  output_text?: string;
};

const body: GenerateRequest = {
  model: "claude-sonnet-5",
  prompt: "a product shot on white marble",
};

const resp = await fetch("https://ugesi.com/api/generate", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.UGESI_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify(body),
});
if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
const job = (await resp.json()) as GenerateResponse;
console.log(job.job_id, job.status);

import requests

resp = requests.post(
    "https://ugesi.com/api/generate",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
        "model": "claude-sonnet-5",
        "prompt": "a product shot on white marble",
    },
    timeout=60,
)
resp.raise_for_status()
print(resp.json())

{
  "model": "claude-sonnet-5",
  "prompt": "a product shot on white marble"
}

The API comes with every credit pack, from Lite to Enterprise, and uses the same balance as the website. API documentation and access →

License and terms of use

Outputs made with paid credits can be used commercially. The maker's own rules for Claude Sonnet 5 also apply (Anthropic Usage Policy). The full rules are in our Terms of service.

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