Providers

llmist supports multiple LLM providers out of the box.

Supported Providers

Provider	Env Variable	Prefix
OpenAI	OPENAI_API_KEY	openai:
Anthropic	ANTHROPIC_API_KEY	anthropic:
Google Gemini	GEMINI_API_KEY	gemini:

Auto-Discovery

llmist automatically discovers providers based on environment variables:

export OPENAI_API_KEY="sk-..."
export ANTHROPIC_API_KEY="sk-ant-..."
export GEMINI_API_KEY="..."

const client = new LLMist();

.withModel('gpt-5')              // OpenAI (auto-detected)
.withModel('claude-sonnet-4-5')  // Anthropic (auto-detected)
.withModel('gemini-2.5-flash')   // Gemini (auto-detected)

Explicit Provider Prefix

Use provider:model format:

.withModel('openai:gpt-5')
.withModel('anthropic:claude-sonnet-4-5-20250929')
.withModel('gemini:gemini-2.5-flash')

Manual Provider Setup

import { LLMist, OpenAIChatProvider, AnthropicMessagesProvider } from 'llmist';

const client = new LLMist({
  autoDiscoverProviders: false,
  adapters: [
    new OpenAIChatProvider({ apiKey: 'sk-...' }),
    new AnthropicMessagesProvider({ apiKey: 'sk-ant-...' }),
  ],
  defaultProvider: 'openai',
});

Creating Custom Providers

interface ProviderAdapter {
  readonly providerId: string;
  readonly priority?: number;

  supports(model: ModelDescriptor): boolean;
  stream(options: LLMGenerationOptions, descriptor: ModelDescriptor): LLMStream;
  getModelSpecs?(): ModelSpec[];
  countTokens?(messages: LLMMessage[], descriptor: ModelDescriptor): Promise<number>;
}

See Also

• Model Catalog - Query available models
• Custom Models - Register fine-tuned models