Claude Sonnet 4.5
Anthropic's mid-tier frontier model — elite coding, agentic tool use, computer control, and reasoning with vision input.
Overview
What is Claude Sonnet 4.5
Claude Sonnet 4.5 is Anthropic's mid-tier frontier model released in September 2025, optimized for coding, agentic workflows, computer use, and reasoning. It accepts text, code, and image inputs with a large context window and is widely regarded as a top-performing model for complex development tasks.
Running it privately on Venice
On Venice, Claude Sonnet 4.5 runs under an anonymized privacy tier — your prompts are not stored, profiled, or used for training. You get the same Anthropic frontier model with vision, reasoning, tool use, and web search capabilities, but without the surveillance footprint of Big-Tech platforms.
Assessment
Strengths and limitations
- Elite coding and agentic performance: Anthropic's top Sonnet release for software development and complex agents.
- Supports vision, multiple image inputs, function calling, structured JSON output, reasoning, and web search for versatile automation.
- Strong computer-use capabilities and long-context handling for multi-step workflows.
- Substantial gains in reasoning and mathematics compared to earlier Claude versions.
- Proprietary closed weights: cannot be self-hosted, fine-tuned, or audited.
- Not uncensored: retains Anthropic's safety alignment and content policies.
- Premium per-token pricing compared to open-weight alternatives on Venice.
- No open-source transparency into architecture, training data, or parameter count.
Capabilities
What it supports
- Tool use / function calling
- Vision (image input)
- Reasoning
- Web search
- Code-optimized
- Structured output (JSON schema)
- Audio input
- Video input
- Multiple image inputs
- Log probabilities
Specifications
Datasheet
- Maker
- Anthropic
- Released
- September 29, 2025
- Open weights
- No — proprietary
- Context window
- 198K tokens
- Max output
- 64K tokens
- Capabilities
- Vision, Function calling, Reasoning, Web search, Code-optimized
- Privacy on Venice
- Anonymized — prompts not stored
- Available on Venice since
- Jan 2025
API
Call it from your code
Venice exposes an OpenAI-compatible API. Point your base URL at Venice and pass the model id.
curl https://api.venice.ai/api/v1/chat/completions \
-H "Authorization: Bearer $VENICE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "claude-sonnet-4-5",
"messages": [{ "role": "user", "content": "Explain quantum tunneling simply." }]
}'Pricing
What it costs on Venice
Billed per token on Venice: $3.75 per 1M input tokens and $18.75 per 1M output tokens.
New Venice accounts include a free daily allowance and 500 welcome credits — no credit card required.
Alternatives
How it compares
| Model | Context window | Strongest at | Open weights | Price (Venice) |
|---|---|---|---|---|
| Claude Sonnet 4.5 | 198K tokens | Coding, agents & computer use | No | $3.75 in · $18.75 out / 1M |
| Claude Sonnet 4.6 | 1M tokens | Coding & real-time agents | No | $3.60 in · $18 out / 1M |
| Claude Opus 4.8 | 1M tokens | Deep reasoning & analysis | No | $6 in · $30 out / 1M |
| DeepSeek V3.2 | 160K tokens | General reasoning | Yes | $0.33 in · $0.48 out / 1M |
Balanced frontier performance with elite coding and agentic capabilities.
Use cases
What it is good for
- 01Complex software development, debugging, and multi-file coding projects.
- 02Agentic automation with tool use, function calling, and structured output.
- 03Visual analysis of screenshots, diagrams, and documents with multiple image inputs.
- 04Cybersecurity analysis, financial modeling, and long-form reasoning tasks.
Prompting
Getting better results
Use structured JSON schema output when building agents that consume model responses programmatically.
Upload screenshots or documents alongside text prompts to leverage vision capabilities for context-rich analysis.
Place key instructions near the start and end of long prompts to improve recall across the 198K context window.
Version history
Prior generation with improved coding over Sonnet 3.7.
Current — elite coding, agents, computer use, and reasoning.
Successor with 1M context and hybrid reasoning.
FAQ
Frequently asked questions
Claude Sonnet 4.5 is Anthropic's mid-tier frontier model released in September 2025. It is optimized for coding, agentic workflows, computer use, reasoning, and vision tasks, offering a balance of capability and speed.
On Venice, Claude Sonnet 4.5 costs $3.75 per million input tokens and $18.75 per million output tokens. Cached input is billed at $0.38 per million tokens.
On Venice, Claude Sonnet 4.5 is billed per token with no subscription required. You pay $3.75 per million input tokens and $18.75 per million output tokens, so costs scale directly with usage.
No. Claude Sonnet 4.5 is a proprietary closed-weight model from Anthropic and cannot be self-hosted or fine-tuned. Open-weight alternatives on Venice include DeepSeek V3.2 and Kimi K2.6.
Yes. On Venice, Claude Sonnet 4.5 supports function calling, structured JSON output, reasoning, web search, and multiple image inputs, making it well-suited for building agents and automated workflows.
Claude Opus 4.8 is Anthropic's flagship tier and generally stronger on deep reasoning and analysis, but it costs roughly twice as much. Sonnet 4.5 is the better value for coding, agents, and high-volume production work.
Yes. It supports vision with multiple image inputs, allowing you to upload screenshots, documents, and photos for analysis alongside text prompts.
Venice runs Claude Sonnet 4.5 under an anonymized privacy tier. Your prompts are not stored, profiled, or used for model training, and no personal account history is tied to your generations.
Run Claude Sonnet 4.5 privately
No prompt logging. No data used for training.