> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/nullclaw/nullclaw/llms.txt
> Use this file to discover all available pages before exploring further.

# Providers Overview

> AI provider system architecture and 50+ supported services

NullClaw supports **50+ AI providers** through a unified vtable-based interface. This enables seamless model switching without changing your agent configuration.

## Provider Interface

All providers implement the `Provider` vtable interface defined in `src/providers/root.zig`:

```zig theme={null}
pub const Provider = struct {
    ptr: *anyopaque,
    vtable: *const VTable,

    pub const VTable = struct {
        chatWithSystem: *const fn (...) anyerror![]const u8,
        chat: *const fn (...) anyerror!ChatResponse,
        supportsNativeTools: *const fn (ptr: *anyopaque) bool,
        getName: *const fn (ptr: *anyopaque) []const u8,
        deinit: *const fn (ptr: *anyopaque) void,
        warmup: ?*const fn (ptr: *anyopaque) void = null,
        supports_streaming: ?*const fn (ptr: *anyopaque) bool = null,
        supports_vision: ?*const fn (ptr: *anyopaque) bool = null,
        stream_chat: ?*const fn (...) anyerror!StreamChatResult = null,
    };
};
```

## Core Providers

NullClaw includes dedicated implementations for these major providers:

* **[OpenAI](/providers/openai)** — GPT-4o, GPT-5, o1, o3, o4
* **[Anthropic](/providers/anthropic)** — Claude 4, Sonnet, Opus
* **[OpenRouter](/providers/openrouter)** — 200+ model aggregator
* **[Ollama](/providers/ollama)** — Local LLMs (Llama, Mistral, Qwen)
* **[Gemini](/providers/gemini)** — Google Gemini 2.0, 1.5 Pro
* **Claude CLI** — Reuses `~/.claude/` credentials
* **Codex CLI** — GitHub Copilot integration
* **OpenAI Codex** — Legacy Codex models

## Compatible Providers (41)

These providers use the OpenAI-compatible API format:

### Major Cloud Providers

* Groq, Mistral, DeepSeek, xAI, Cerebras, Perplexity, Cohere

### Gateways & Aggregators

* Venice, Vercel AI Gateway, Together AI, Fireworks AI, Hugging Face
* AIHubMix, SiliconFlow, Chutes, Synthetic, Poe

### China Providers

* Moonshot (Kimi), GLM (Zhipu), Z.AI, MiniMax, Qwen, Qianfan, Doubao

### Infrastructure

* Amazon Bedrock, Cloudflare AI Gateway, GitHub Copilot, NVIDIA NIM, OVHcloud

### Local Servers

* LM Studio, vLLM, llama.cpp, SGLang, Osaurus, LiteLLM

## Provider Selection

Select a provider in `~/.nullclaw/config.json`:

```json theme={null}
{
  "provider": "anthropic",
  "model": "claude-sonnet-4",
  "api_key": "sk-ant-..."
}
```

For OpenRouter:

```json theme={null}
{
  "provider": "openrouter",
  "model": "openrouter/anthropic/claude-sonnet-4",
  "api_key": "sk-or-..."
}
```

For local Ollama:

```json theme={null}
{
  "provider": "ollama",
  "model": "llama3.2",
  "base_url": "http://localhost:11434"
}
```

## Custom Endpoints

Use `custom:` prefix for arbitrary OpenAI-compatible endpoints:

```json theme={null}
{
  "provider": "custom:https://api.example.com/v1",
  "model": "my-model",
  "api_key": "..."
}
```

Use `anthropic-custom:` for Anthropic-format endpoints:

```json theme={null}
{
  "provider": "anthropic-custom:https://proxy.example.com",
  "model": "claude-sonnet-4"
}
```

## Capabilities

| Capability              | Description                 |
| ----------------------- | --------------------------- |
| `supportsNativeTools()` | Function calling / tool use |
| `supportsStreaming()`   | SSE streaming responses     |
| `supportsVision()`      | Image/multimodal input      |
| `warmup()`              | Pre-warm TLS connections    |

## Provider-Specific Notes

* **OpenAI**: Supports reasoning models (o1, o3, gpt-5) with `reasoning_effort` parameter
* **Anthropic**: OAuth tokens (`sk-ant-oat01-`) use Bearer auth instead of x-api-key
* **Gemini**: Supports API keys, OAuth, and Gemini CLI (`~/.gemini/oauth_creds.json`)
* **Ollama**: No authentication required for local servers
* **OpenRouter**: Requires `HTTP-Referer` and `X-Title` headers

## Next Steps

* [OpenAI Configuration](/providers/openai)
* [Anthropic Configuration](/providers/anthropic)
* [OpenRouter Configuration](/providers/openrouter)
* [Ollama Local Setup](/providers/ollama)
* [Gemini Configuration](/providers/gemini)