✨ Multi-Format API

Use OpenAI, Anthropic, or Gemini formats with a single API key

Overview

LemonData supports three native API formats with a single API key. Choose the format that best fits your use case - no configuration changes needed.

OpenAI Format

/v1/chat/completions Standard format, widest compatibility

Anthropic Format

/v1/messages Extended thinking, native Claude features

Gemini Format

/v1beta/models/:model:generateContent Google ecosystem integration

Why Multi-Format?

Benefit	Description
No SDK switching	Use any model with your preferred SDK
Native features	Access format-specific capabilities
Native-first migration	Keep native provider routes when behavior matters; use /v1 OpenAI compatibility for existing OpenAI-style clients
Single billing	One account, one API key, all formats

Format Comparison

Feature	OpenAI	Anthropic	Gemini
Endpoint	/v1/chat/completions	/v1/messages	/v1beta/models/:model:generateContent
Auth Header	Authorization: Bearer	x-api-key	Authorization: Bearer
System Prompt	In messages array	Separate system field	In systemInstruction
Extended Thinking	❌	✅	❌
Streaming	✅ SSE	✅ SSE	✅ SSE
Tool Calling	✅	✅	✅
Vision	✅	✅	✅

OpenAI Format

Use this compatibility route for existing OpenAI SDK integrations and portable chat or embedding flows. For Claude or Gemini native behavior, use the Anthropic or Gemini format below.

from openai import OpenAI

client = OpenAI(
    api_key="sk-your-lemondata-key",
    base_url="https://api.lemondata.cc/v1"
)

# Portable chat works across many models
response = client.chat.completions.create(
    model="claude-sonnet-4-6",  # Claude via OpenAI format
    messages=[
        {"role": "system", "content": "You are a helpful assistant."},
        {"role": "user", "content": "Hello!"}
    ]
)

Best for:

• General use
• Existing OpenAI SDK integrations
• Maximum compatibility

Anthropic Format

Native Anthropic Messages API. Required for Claude-specific features like extended thinking.

from anthropic import Anthropic

client = Anthropic(
    api_key="sk-your-lemondata-key",
    base_url="https://api.lemondata.cc"  # No /v1 suffix!
)

message = client.messages.create(
    model="claude-sonnet-4-6",
    max_tokens=1024,
    system="You are a helpful assistant.",  # Separate system field
    messages=[
        {"role": "user", "content": "Hello!"}
    ]
)

Extended Thinking (Claude Opus 4.6)

Only available in Anthropic format:

message = client.messages.create(
    model="claude-opus-4-6",
    max_tokens=16000,
    thinking={
        "type": "enabled",
        "budget_tokens": 10000
    },
    messages=[{"role": "user", "content": "Solve this complex problem..."}]
)

# Access thinking process
for block in message.content:
    if block.type == "thinking":
        print(f"Thinking: {block.thinking}")
    elif block.type == "text":
        print(f"Answer: {block.text}")

Best for:

• Claude-specific features
• Extended thinking mode
• Native Anthropic SDK users

Gemini Format

Native Google Gemini API format for Google ecosystem integration.

curl "https://api.lemondata.cc/v1beta/models/gemini-2.5-flash:generateContent" \
  -H "Authorization: Bearer sk-your-lemondata-key" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [{
      "parts": [{"text": "Hello!"}]
    }],
    "systemInstruction": {
      "parts": [{"text": "You are a helpful assistant."}]
    }
  }'

Streaming

curl "https://api.lemondata.cc/v1beta/models/gemini-2.5-flash:streamGenerateContent?alt=sse" \
  -H "Authorization: Bearer sk-your-lemondata-key" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [{"parts": [{"text": "Write a story"}]}]
  }'

Best for:

• Google Cloud integrations
• Existing Gemini SDK code
• Native Gemini features

Gemini Files and Cache: /upload/v1beta/files, /v1beta/files, /v1beta/files:register, and /v1beta/cachedContents are available on the native Gemini route. Files use Gemini File API-compatible upstream channels; explicit cache resources can also route through Vertex AI channels. Resources created through LemonData are bound to the same upstream channel/key for later generateContent calls.

Tool Compatibility Boundary

Function tools can be converted between formats when the target route supports them. Provider-native tools must stay on their native route:

• OpenAI Responses hosted and native tools such as tool_search, web_search, file_search, code_interpreter, MCP, shell/apply_patch, and computer-use tools require /v1/responses.
• Anthropic server/native tools such as web_search_*, web_fetch_*, code_execution_*, tool_search_*, bash, computer-use, and text-editor tools require /v1/messages.
• Gemini built-in tools such as googleSearch, codeExecution, urlContext, computerUse, and similar tools fields require /v1beta.

If LemonData cannot route a request with native tools to a native-capable upstream path, it returns an explicit unsupported-field error instead of dropping the tool or pretending it is a Chat Completions function. User-defined function tools remain the portable path.

Choosing the Right Format

Migration Guides

From OpenAI Official API

# Before (OpenAI)
client = OpenAI(api_key="sk-openai-key")

# After (LemonData)
client = OpenAI(
    api_key="sk-lemondata-key",
    base_url="https://api.lemondata.cc/v1"  # Add this line
)
# That's it! Same code works

From Anthropic Official API

# Before (Anthropic)
client = Anthropic(api_key="sk-ant-key")

# After (LemonData)
client = Anthropic(
    api_key="sk-lemondata-key",
    base_url="https://api.lemondata.cc"  # Add this line (no /v1!)
)

From Google AI Studio

# Before (Google)
import google.generativeai as genai
genai.configure(api_key="google-api-key")

# After (LemonData) - Use REST API
import requests

response = requests.post(
    "https://api.lemondata.cc/v1beta/models/gemini-2.5-flash:generateContent",
    headers={"Authorization": "Bearer sk-lemondata-key"},
    json={"contents": [{"parts": [{"text": "Hello"}]}]}
)

Cross-Model Compatibility

LemonData supports cross-format conversion for portable chat workflows. Use native routes when provider-specific features matter.

Compatibility SDK → Portable Chat

# Anthropic SDK with GPT-4o (auto-converts to OpenAI format)
from anthropic import Anthropic

client = Anthropic(
    api_key="sk-lemondata-key",
    base_url="https://api.lemondata.cc"
)

response = client.messages.create(
    model="gpt-4o",  # ✅ Works! Auto-converted
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}]
)

# Same compatibility SDK for portable chat; native-only features still need native routes
response = client.messages.create(model="gemini-2.5-flash", ...)  # ✅ Works!
response = client.messages.create(model="deepseek-r1", ...)       # ✅ Works!

OpenAI SDK → Portable Chat Models

from openai import OpenAI

client = OpenAI(base_url="https://api.lemondata.cc/v1", api_key="sk-...")

# These portable chat calls use the same /v1 compatibility SDK:
response = client.chat.completions.create(model="gpt-4o", ...)
response = client.chat.completions.create(model="claude-sonnet-4-6", ...)
response = client.chat.completions.create(model="gemini-2.5-flash", ...)

Industry Comparison

Platform	OpenAI Format	Anthropic Format	Gemini Format	Responses API
LemonData	✅ All models	✅ All models	✅ All models	✅ All models
OpenRouter	✅ All models	❌	❌	❌
Together AI	✅ All models	❌	❌	❌
Fireworks	✅ All models	❌	❌	❌

While cross-format works for most features, format-specific features (like Anthropic extended thinking) require the native format.