---
title: "Grok API — Variants, pricing & model skill"
url: "https://runapi.ai/models/grok.md"
canonical: "https://runapi.ai/models/grok.md"
locale: "en"
model: "Grok"
provider: "xAI"
modality: "text"
variant_count: 2
price_from_cents: 3
---

# Grok API

xAI Grok 4.3 and 4.5 API access through RunAPI Responses and Chat Completions for reasoning, tools, and structured output.

**Provider:** xAI
**Modality:** Text
**Catalog:** 2 variants

Grok 4.3 and Grok 4.5 are xAI language models for reasoning, function tools, and structured output. Use the exact model ids grok-4.3 and grok-4.5 through RunAPI Responses; Grok 4.5 also supports Chat Completions.

## Variants

| Version | Variant | Pricing | Billing | URL |
|---|---|---|---|---|
| grok-4.3 | `4.3` | $0.030 | 1K tokens | https://runapi.ai/models/grok/4.3.md |
| grok-4.5 | `4.5` | $0.060 | 1K tokens | https://runapi.ai/models/grok/4.5.md |


## API endpoints

Base URL: `https://runapi.ai`

- `POST /v1/chat/completions`
- `POST /v1/responses`
- `POST /v1/messages`
- `POST /v1beta/models/{model}:generateContent`
- `POST /v1beta/models/{model}:streamGenerateContent`

Use the OpenAI or Anthropic SDK with your RunAPI API key. No extra SDK required.

## Context

Grok 4.3 and 4.5 serve conversational, coding, and agentic workloads through RunAPI with one API key, synchronous or streaming responses, and terminal usage reporting.

## FAQ

### Which variant should I start with?

Pick the cheapest variant that meets your quality bar. Most teams start on the fast variant and graduate to pro for production.

### Is there a free tier?

New accounts get free first calls on every model. After that, pay per call.

### Do you stream results?

Where streaming is available, RunAPI streams end-to-end.

### How are failures billed?

Failed generations are not charged.

### Are outputs cached?

Generated outputs are stored and retrievable by task ID. Inputs are not cached.

### Can I use commercially?

Yes — commercial use is included for every variant unless a model license explicitly restricts it, which is called out on the variant page.

### What about rate limits?

Per-key rate limits scale with usage tier. See pricing page for current limits.

### Where can I report issues?

Open an issue on the public GitHub repo or email support.