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The LLM node invokes language models to process text, images, and documents. It sends prompts to your configured models and captures their responses, supporting structured outputs, context management, and multimodal inputs.
LLM Node Overview

LLM node configuration interface

Configure at least one model provider in System Settings → Model Providers before using LLM nodes. See how to install model plugins for setup instructions.

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Model Selection and Parameters

Choose from any model provider you’ve configured. Different models excel at different tasks - GPT-4 and Claude 3.5 handle complex reasoning well but cost more, while GPT-3.5 Turbo balances capability with affordability. For local deployment, use Ollama, LocalAI, or Xinference.
LLM Node Configuration

Model selection and parameter configuration

Model parameters control response generation. Temperature ranges from 0 (deterministic) to 1 (creative). Top P limits word choices by probability. Frequency Penalty reduces repetition. Presence Penalty encourages new topics. You can also use presets: Precise, Balanced, or Creative.

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Prompt Configuration

Your interface adapts based on model type. Chat models use message roles (System for behavior, User for input, Assistant for examples), while completion models use simple text continuation. Reference workflow variables in prompts using double curly braces: {{variable_name}}. Variables are replaced with actual values before reaching the model. 
System: You are a technical documentation expert.
User: {{user_input}}

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Context Variables

Context variables inject external knowledge while preserving source attribution. This enables RAG applications where LLMs answer questions using your specific documents.
Context Variables

Using context variables for RAG applications

Connect a Knowledge Retrieval node’s output to your LLM node’s context input, then reference it: 
Answer using only this context:
{{knowledge_retrieval.result}}

Question: {{user_question}}
When using context variables from knowledge retrieval, Dify automatically tracks citations so users see information sources.

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Structured Outputs

Force models to return specific data formats like JSON for programmatic use. Configure through three methods:
  • Visual Editor
  • JSON Schema
  • AI Generation
User-friendly interface for simple structures. Add fields with names and types, mark required fields, set descriptions. The editor generates JSON Schema automatically.
Models with native JSON support handle structured outputs reliably. For others, Dify includes the schema in prompts, but results may vary.

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Memory and File Processing

Enable Memory to maintain context across multiple LLM calls within a chatflow conversation. When enabled, previous interactions will be included in subsequent prompts as formatted user - assistant outputs. You can customize what goes into the user prompts by editing the USER template. Memory is node-specific and doesn’t persist between different conversations. For File Processing, add file variables to prompts for multimodal models. GPT-4V handles images, Claude processes PDFs directly, while other models might need preprocessing.

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Vision Configuration

When processing images, you can control the detail level:
  • High detail - Better accuracy for complex images but uses more tokens
  • Low detail - Faster processing with fewer tokens for simple images
The default variable selector for vision is sys.files which automatically picks up files from the Start node.
File Processing

File processing with multimodal LLMs

For conversation history in completion models, insert conversation variables to maintain multi-turn context:
Conversation History

Using conversation history variables

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Jinja2 Template Support

LLM prompts support Jinja2 templating for advanced variable handling. When you use Jinja2 mode (edition_type: "jinja2"), you can: 
{% for item in search_results %}
{{ loop.index }}. {{ item.title }}: {{ item.content }}
{% endfor %}
Jinja2 variables are processed separately from regular variable substitution, allowing for loops, conditionals, and complex data transformations within prompts.

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Streaming Output

LLM nodes support streaming output by default. Each text chunk is yielded as a RunStreamChunkEvent, enabling real-time response display. File outputs (images, documents) are processed and saved automatically during streaming.

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Error Handling

Configure retry behavior for failed LLM calls. Set maximum retry attempts, intervals between retries, and backoff multipliers. Define fallback strategies like default values, error routing, or alternative models when retries aren’t sufficient.