# Claude Sonnet 4

> Claude Sonnet 4 is a proprietary language model from Anthropic, released on 22 May 2025. It accepts images, text and PDFs and generates text, with a 200K-token context window and up to 64K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $3 per million input tokens and $15 per million output tokens (OpenRouter), across 2 providers we track.

Source page: https://www.aimodel.directory/models/claude-sonnet-4
Last verified: 4 Oct 2026

## Specifications

- **Developer:** Anthropic
- **Release date:** 22 May 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Weights:** Proprietary (API only) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Context window:** 200K (200,000 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Max output:** 64K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Knowledge cutoff:** 31 Jan 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Input:** Images, text and PDFs (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Reasoning mode:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)
- **Structured output:** No (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/openrouter/models/anthropic/claude-sonnet-4.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| OpenRouter | $3 | $15 | $0.30 | 200K |
| Vercel AI Gateway | $3 | $15 | $0.30 | 1M |

## FAQ

### What is the context window of Claude Sonnet 4?

Claude Sonnet 4 has a context window of 200,000 tokens (200K) and can generate up to 64,000 tokens in a single response, according to models.dev.

### How much does the Claude Sonnet 4 API cost?

Claude Sonnet 4 is listed from $3 per million input tokens and $15 per million output tokens (OpenRouter). Prices last verified 4 Oct 2026.

### Is Claude Sonnet 4 open source?

No. Claude Sonnet 4 is a proprietary model; Anthropic has not released its weights. It is available through APIs including OpenRouter, Vercel AI Gateway.

### When was Claude Sonnet 4 released?

Anthropic released Claude Sonnet 4 on 22 May 2025, according to models.dev.

### Which providers offer Claude Sonnet 4?

We track Claude Sonnet 4 on 2 providers: OpenRouter, Vercel AI Gateway.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "Claude Sonnet 4", https://www.aimodel.directory/models/claude-sonnet-4