Responses API vs Chat Completions

RECOMMENDED

Responses API

Stateful, agentic workflows

vs

STABLE

Chat Completions

Stateless, simple requests

Feature Comparison

Feature	Responses API	Chat Completions
State Management	✓ Built-in conversation state	✗ Stateless, manage yourself
Tool Use	✓ Native, multi-turn	✓ Function calling
File Handling	✓ Built-in file attachments	✗ Base64 encoding only
Streaming	✓ Server-Sent Events	✓ Server-Sent Events
Context Caching	✓ Automatic	✓ Manual
Web Search	✓ Built-in tool	✗ Not available
Code Interpreter	✓ Built-in	✗ Use Assistants API
Computer Use	✓ Supported	✗ Not available
OpenAI Compatible	✗ New format	✓ Drop-in replacement

Code Examples

                        Responses API
                    

# Stateful conversation
response = client.responses.create(
    model="mythic-4",
    input="Analyze this data",
    tools=[{"type": "code_interpreter"}],
    attachments=[
        {"file_id": file.id}
    ]
)

# Continue conversation
response2 = client.responses.create(
    model="mythic-4",
    input="Now create a chart",
    previous_response_id=response.id
)
                    

                        Chat Completions
                    

# Stateless, pass full history
messages = [
    {"role": "system", "content": "..."},
    {"role": "user", "content": "Hello"}
]

response = client.chat.completions.create(
    model="mythic-4",
    messages=messages
)

# Continue - append manually
messages.append(response.choices[0].message)
messages.append({"role": "user", ...})
                    

When to Use Each

🚀 Use Responses API when:

Building conversational agents
Using tools like code interpreter
Handling file attachments
Need web search capabilities
Building multi-turn workflows
Want automatic state management

📝 Use Chat Completions when:

Simple, one-off generations
Need OpenAI API compatibility
Migrating from existing code
Custom state management required
Using with existing SDKs
Batch processing pipelines

💡 Recommendation

For new projects, we recommend starting with the Responses API. It's more powerful, handles state for you, and includes built-in tools. Use Chat Completions if you need OpenAI compatibility or have existing integrations.

Get Started

Explore the full documentation for each API.

Responses API → Chat Completions →