Struktur is built on the Vercel AI SDK, which provides a unified interface to multiple LLM providers. This architecture makes it straightforward to use any model from supported providers—or add new ones.

Supported Providers

Struktur currently supports the following providers out of the box:

Provider	Environment Variable	Package
OpenAI	`OPENAI_API_KEY`	`@ai-sdk/openai`
Anthropic	`ANTHROPIC_API_KEY`	`@ai-sdk/anthropic`
Google	`GOOGLE_GENERATIVE_AI_API_KEY`	`@ai-sdk/google`
OpenCode	`OPENCODE_API_KEY`	`@ai-sdk/openai`*
OpenRouter	`OPENROUTER_API_KEY`	`@openrouter/ai-sdk-provider`

*OpenCode uses the OpenAI-compatible API via the Vercel SDK's OpenAI provider.

Model names change frequently. Rather than document specific models, Struktur focuses on provider integration. Check your provider's documentation for available models and their capabilities.

Specifying Models

Models are specified using the format provider/model-name:

import { extract } from "@struktur/sdk";

// OpenAI
const result = await extract({
  artifacts,
  schema,
  strategy: { type: "simple", model: "openai/gpt-4o" }
});

// Anthropic
const result = await extract({
  artifacts,
  schema,
  strategy: { type: "simple", model: "anthropic/claude-3-5-sonnet" }
});

// Google
const result = await extract({
  artifacts,
  schema,
  strategy: { type: "simple", model: "google/gemini-1.5-pro" }
});

Authentication

Struktur supports two authentication methods:

Environment Variables

Set the appropriate API key for your provider:

export OPENAI_API_KEY="sk-..."
export ANTHROPIC_API_KEY="sk-ant-..."
export GOOGLE_GENERATIVE_AI_API_KEY="..."
export OPENCODE_API_KEY="..."
export OPENROUTER_API_KEY="..."

Secure Token Storage

For CLI usage, Struktur can store tokens securely:

# Store in macOS Keychain (preferred on macOS)
struktur auth set --provider openai --token "sk-..."

# Or store in file
struktur auth set --provider openai --token "sk-..." --storage file

On macOS, Struktur defaults to the system Keychain. On other platforms, tokens are stored in ~/.config/struktur/tokens.json with strict permissions (0o600).

Special Providers

OpenCode (PyCoding Agent)

OpenCode provides access to multiple model families through a single API:

// OpenAI-compatible models
"opencode/gpt-5.2"
"opencode/gpt-5.1"

// Anthropic-compatible models
"opencode/claude-opus-4-6"
"opencode/claude-sonnet-4-5"

// Google-compatible models
"opencode/gemini-3.1-pro"
"opencode/gemini-3-flash"

// Other providers
"opencode/kimi-k2.5"
"opencode/glm-5"

Struktur automatically routes OpenCode requests to the correct Vercel SDK provider based on the model prefix (gpt-, claude-, gemini-).

OpenRouter

OpenRouter provides access to models from multiple providers through a unified API. You can also specify a preferred upstream provider:

// Basic usage
"openrouter/anthropic/claude-3.5-sonnet"

// With preferred provider (using hashtag syntax)
"openrouter/anthropic/claude-3.5-sonnet#octoai"

Adding New Providers

Because Struktur uses the Vercel AI SDK, adding support for new providers is straightforward:

Check if Vercel AI SDK supports the provider

The Vercel AI SDK has a growing ecosystem of community providers. If your provider is listed there, integration is simple.

Create a provider resolver

Add a case to resolveModel in packages/sdk/src/llm/resolveModel.ts:

case "newprovider": {
  const { createNewProvider } = await import("@ai-sdk/newprovider");
  return createNewProvider({ apiKey })(modelName);
}

Add environment variable mapping

Update resolveProviderEnvVar in packages/sdk/src/auth/tokens.ts:
```
case "newprovider":
  return "NEWPROVIDER_API_KEY";
```
(Optional) Add model listing support

If the provider has a models API, add support in packages/sdk/src/llm/models.ts.

Model Capabilities

When selecting a model, consider:

Capability	Considerations
Structured Output	All supported providers support JSON schema output
Vision/Multimodal	Check if the model supports image input for PDF/image extraction
Context Window	Larger documents require models with larger context windows
Rate Limits	Consider provider rate limits for batch processing
Cost	Different models have vastly different pricing

Not all models support image inputs. If you're extracting from PDFs or images with visual content, use a vision-capable model (e.g., GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 Pro).

Listing Available Models

The CLI can list available models from configured providers:

# List models for a specific provider
struktur models --provider openai

# List models for all configured providers
struktur models

# Pick the cheapest available model
struktur extract --model cheapest --provider openai

Models and Providers