Anthropic-compatible API

Create a Vani key, then give the Anthropic SDK Vani's origin as its base URL. max_tokens is required, as on Anthropic's API.

import os
from anthropic import Anthropic

client = Anthropic(base_url="https://api.vani.ai", api_key=os.environ["VANI_API_KEY"])

message = client.messages.create(
    model="anthropic/claude-sonnet-5.5",  # any id from GET /models
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}],
)
print(message.content)

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({ baseURL: "https://api.vani.ai", apiKey: process.env.VANI_API_KEY });

const message = await client.messages.create({
  model: "openai/gpt-6-sol", // any id from GET /models
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello" }],
});
console.log(message.content);

curl "https://api.vani.ai/v1/messages" \
  -H "x-api-key: $VANI_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-sonnet-5.5","max_tokens":256,"messages":[{"role":"user","content":"Hello"}]}'

• Text and system blocks, tool_use and tool_result, tool definitions and tool_choice, max_tokens, stop_sequences, and streaming and non-streaming answers.
• MCP servers: mcp_servers with the anthropic-beta header mcp-client-2025-11-20 (mcp-client-2026-09-15 and mcp-client-2025-04-04 are accepted too).
• thinking sets the reasoning effort unless output_config.effort does. Thinking blocks are not returned; usage.output_tokens_details.thinking_tokens says how much of the output was reasoning.
• cache_control hints on system and user text blocks are passed to the model's provider where it takes them (x-vani-cache-hints: forwarded); a cache hit is never guaranteed, and usage.cache_read_input_tokens shows what was billed as cached.
• POST /messages/count_tokens returns a local estimate (x-vani-token-count: local-estimate); billing uses the provider's usage.

MCP tools on the API

Claude Code talks to the Messages endpoint. Set ANTHROPIC_BASE_URL to Vani's origin without /v1 and ANTHROPIC_API_KEY to your Vani key (never an Anthropic key), choose any model id, and keep your normal permission settings. These are the settings tested in the Claude Code guide:

export ANTHROPIC_BASE_URL='https://api.vani.ai'
export ANTHROPIC_API_KEY='vani_YOUR_VANI_API_KEY'
export ANTHROPIC_MODEL='openai/gpt-6-sol'
export CLAUDE_CODE_DISABLE_THINKING=1
export CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1
export DISABLE_PROMPT_CACHING=1
export ENABLE_TOOL_SEARCH=false

Claude Code and other client guides

• Model ids name their maker, for example anthropic/claude-sonnet-5.5 or openai/gpt-6-sol. Anthropic's own ids, such as claude-haiku-4-5, are accepted when they name exactly one model your key can use.
• Text only: image and document blocks, hosted server tools and unsupported beta features are refused with 400 before a model runs, so nothing is billed.
• top_k is accepted and ignored.

Model ids, limits, headers and usageAPI prices per model