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AI API Documentation Reference

ChatGPT API (OpenAI)​

Overview​

OpenAI provides access to ChatGPT models through their API, allowing developers to integrate conversational AI capabilities into applications, websites, and services.

Key Features​

  • Multiple GPT models with different capabilities and price points
  • Function calling for structured outputs
  • Image generation and analysis
  • Fine-tuning options
  • Embeddings for semantic search

Main Endpoints​

  • /chat/completions - For chat-based interactions
  • /images/generations - For DALL-E image generation
  • /embeddings - For creating vector embeddings
  • /audio/speech - For text-to-speech generation
  • /audio/transcriptions - For speech-to-text conversion

Documentation Resources​

Pricing and Token Information​

  • https://openai.com/pricing
  • Pricing is based on token usage (input and output tokens)
  • Token conversion is the same as Claude (1 token ≈ 3/4 of a word)

GPT-4o Pricing:​

  • Input: $5/MTok ($0.005 per 1K tokens)
  • Output: $15/MTok ($0.015 per 1K tokens)
  • Context window: 128K tokens

GPT-4 Turbo Pricing:​

  • Input: $10/MTok ($0.01 per 1K tokens)
  • Output: $30/MTok ($0.03 per 1K tokens)
  • Context window: 128K tokens

GPT-3.5 Turbo Pricing:​

  • Input: $0.50/MTok ($0.0005 per 1K tokens)
  • Output: $1.50/MTok ($0.0015 per 1K tokens)
  • Context window: 16K tokens

Examples:​

  • 1,000 word document input with GPT-4o: ~1,333 tokens = $0.0067
  • 1,000 word response with GPT-4o: ~1,333 tokens = $0.02
  • Full conversation (5,000 words) with GPT-3.5 Turbo: ~$0.01

Anthropic Claude API​

Overview​

Anthropic provides access to Claude models through their API, enabling developers to integrate Claude's natural language understanding and generation capabilities into applications.

Key Features​

  • Multiple Claude model options (Claude 3 Opus, Sonnet, Haiku)
  • Long context windows (up to 200K tokens)
  • Structured tool use capabilities
  • Prompt caching for cost efficiency
  • Multi-modal capabilities (text and images)

Main Endpoints​

  • /v1/messages - For message-based interactions
  • /v1/completions - Legacy API for text completions

Documentation Resources​

Pricing and Token Information​

Claude 3.7 Sonnet Pricing:​

  • Input: $3/MTok ($0.003 per 1K tokens)
  • Output: $15/MTok ($0.015 per 1K tokens)
  • Prompt caching: $3.75/MTok write, $0.30/MTok read
  • Context window: 200K tokens

Claude 3 Opus Pricing:​

  • Input: $15/MTok ($0.015 per 1K tokens)
  • Output: $75/MTok ($0.075 per 1K tokens)
  • Context window: 200K tokens

Claude 3.5 Haiku Pricing:​

  • Input: $0.25/MTok ($0.00025 per 1K tokens)
  • Output: $1.25/MTok ($0.00125 per 1K tokens)
  • Context window: 200K tokens

Examples:​

  • 1,000 word document input with Claude 3.7 Sonnet: ~1,333 tokens = $0.004
  • 1,000 word response with Claude 3.7 Sonnet: ~1,333 tokens = $0.02
  • Full conversation (5,000 words) with Claude 3.5 Haiku: ~$0.008

Token Conversion Guide​

Understanding Tokens vs. Words​

Tokens are the basic units that AI models process text. Here's how to convert between tokens and words:

General Conversion Rules​

  • 1 token ≈ 4 characters in English
  • 1 token ≈ 3/4 of an English word
  • 1,000 tokens ≈ 750 words
  • 1 million tokens (1 MTok) ≈ 750,000 words

Word Count Examples​

  • Short email (100 words) ≈ 133 tokens
  • 1-page document (500 words) ≈ 667 tokens
  • 10-page report (5,000 words) ≈ 6,667 tokens
  • Novel (80,000 words) ≈ 106,667 tokens

Calculating Costs​

For Claude 3.7 Sonnet:

  • 1,000 word input ≈ 1,333 tokens ≈ $0.004 (at $3/MTok)
  • 1,000 word output ≈ 1,333 tokens ≈ $0.02 (at $15/MTok)
  • A typical conversation with 5,000 words total ≈ $0.10

For GPT-4o:

  • 1,000 word input ≈ 1,333 tokens ≈ $0.0067 (at $5/MTok)
  • 1,000 word output ≈ 1,333 tokens ≈ $0.02 (at $15/MTok)
  • A typical conversation with 5,000 words total ≈ $0.13

API Cost Comparison (for processing 100,000 words)​

ModelInput CostOutput CostTotal (50/50 split)
GPT-3.5 Turbo$0.07$0.20$0.27
Claude 3.5 Haiku$0.03$0.17$0.20
Claude 3.7 Sonnet$0.40$2.00$2.40
GPT-4o$0.67$2.00$2.67
Claude 3 Opus$2.00$10.00$12.00
GPT-4 Turbo$1.33$4.00$5.33

Other Considerations​

  • Code, technical content, and non-English languages may have different token-to-word ratios
  • Spaces, punctuation, and special characters also count as tokens
  • Shorter words take fewer tokens (e.g., "I" is 1 token, "indubitably" might be 4 tokens)

Integration Code Examples​

OpenAI ChatGPT Example​

from openai import OpenAI
client = OpenAI(api_key="your-api-key")

response = client.chat.completions.create(
  model="gpt-4o",
  messages=[
    {"role": "system", "content": "You are a helpful assistant."},
    {"role": "user", "content": "Tell me about AI APIs"}
  ],
  max_tokens=100
)

print(response.choices[0].message.content)

Anthropic Claude Example​

import anthropic

client = anthropic.Anthropic(api_key="your-api-key")

message = client.messages.create(
    model="claude-3-7-sonnet-20250219",
    system="You are a helpful assistant.",
    messages=[
        {"role": "user", "content": "Tell me about AI APIs"}
    ],
    max_tokens=100
)

print(message.content[0].text)

Important Considerations​

Rate Limits​

  • Both APIs have rate limits based on requests per minute and tokens per minute
  • OpenAI has different rate limits based on spend
  • Anthropic has different rate limits based on organization tier

Authentication​

  • Both require API keys for authentication
  • Should be kept secure and not exposed in client-side code
  • Environment variables are recommended for storing API keys

Tokens​

  • Both APIs measure usage in tokens (~4 characters or ~3/4 of a word)
  • Consider token usage carefully for cost efficiency
  • Both charge separately for input and output tokens

Data Privacy​