ライティング向けAI API比較：ChatGPT、Claude、Gemini、Writesonic

Choosing an AI API or tool for writing (blog posts, product descriptions, SEO content, copywriting) comes down to balancing cost, quality and volume. This comparison helps you decide.

What to look at for writing

- Price per million tokens: most APIs charge by usage (input + output). For long-form writing (articles, briefs), output volume often matters more than input. Compare input/output rates in our table. - Quality and consistency: GPT-4o, Claude and Gemini deliver strong editorial content. Lighter models (GPT-4o mini, Gemini Flash) suit first drafts or high volume at lower cost. - Dedicated tools: Writesonic, Jasper, Copy.ai or Rytr target writing and SEO directly, with templates and workflows. They can be easier than a raw API if you don’t want to build everything yourself.

ChatGPT, Claude, Gemini: ballpark for writing

OpenAI (GPT-4o, GPT-4o mini), Anthropic (Claude Sonnet, Claude Haiku) and Google (Gemini Pro, Gemini Flash) all offer models suited to writing. The right one depends on your monthly budget and token volume. Use the Compare IA comparator filtered by use case “Writing” and max budget to see matching models.

When to choose an API vs a tool like Writesonic

- API: if you already have an app or pipeline (CMS, automation), an API (OpenAI, Anthropic, Google, Mistral) is often more flexible and scalable. - All-in-one tool (Writesonic, Jasper, etc.): if you want to write without coding, with SEO briefs and a ready-made interface, a dedicated tool can be more cost-effective.

In short: define your volume (tokens or words/month), budget and need (API vs tool). Then use the Compare IA comparison table filtered by “Writing” to compare price per million tokens and find the best fit.