Grok 4.20 Reasoning
Grok 4.20 Reasoning is SpaceXAI's reasoning model in the Grok 4.20 beta generation, supporting extended thinking for complex problem-solving with low hallucination rates and strict prompt adherence.
View API reference- Input and output price
- Prices from: Input $1.25, Output $2.50, Per 1M tokens
- 24h uptime
- Loading AI Gateway uptime
import { streamText } from 'ai'
const result = streamText({ model: 'spacexai/grok-4.20-reasoning', prompt: 'Why is the sky blue?'})Copy link to headingPlayground
Try out Grok 4.20 Reasoning by SpaceXAI. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
Grok 4.20 Reasoning
Grok 4.20 Reasoning
Copy link to headingProviders
Route requests across multiple providers. Copy a provider slug to set your preference. Visit the docs for more info. Using a provider means you agree to their terms, listed under Legal.
Copy link to headingUptime24 hours
Direct request success rate on AI Gateway and per-provider. Visit the docs for more info.
Copy link to headingThroughput24 hours
P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
Copy link to headingLatency24 hours
P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.
Getting started
Call Grok 4.20 Reasoning through AI Gateway with the AI SDK generateText and streamText functions, or through the OpenAI Chat Completions, OpenAI Responses, and Anthropic Messages APIs by changing the base URL. AI Gateway authenticates the request and routes it to an available provider.
Install the AI SDK (pnpm add ai dotenv), create an API key from the API Keys page, and set it as AI_GATEWAY_API_KEY in your environment. Full setup is covered in the text generation quickstart.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', prompt: 'Why is the sky blue?', });
console.log(result.text);}
main().catch(console.error);Top-level parameters
The same Grok 4.20 Reasoning request in each API format AI Gateway supports.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', system: 'You are a concise technical assistant.', prompt: 'Summarize the tradeoffs between static generation and SSR.', maxOutputTokens: 1024, });
console.log(result.text);}
main().catch(console.error);Standard parameters like prompt, messages, temperature, and tools work as documented in the AI SDK docs. These are the parameters with model-specific behavior.
| Parameter | Type | Required | Description |
|---|---|---|---|
model | string | Yes | Model ID in the form creator/model, e.g. spacexai/grok-4.20-reasoning. AI Gateway routes the request to an available provider. |
maxOutputTokens | number | No | Hard cap on generated tokens. Grok 4.20 Reasoning supports up to 2,000,000 output tokens. Reasoning tokens count toward this limit. |
reasoning | 'provider-default' | 'none' | 'minimal' | 'low' | 'medium' | 'high' | 'xhigh' | No | Provider-agnostic reasoning effort, available in AI SDK 7 or later. Maps to the provider’s native reasoning configuration; reasoning settings under providerOptions take precedence when both are set. See the Reasoning section below. |
providerOptions | Record<string, JSONValue> | No | AI Gateway routing options under gateway, plus any provider-native options under the provider’s own namespace — see the table below. |
Input limits
| Input | Formats | Sources | Max count | Max size | Limits |
|---|---|---|---|---|---|
| Text | — | — | — | — | Prompt and response share the 2M-token context window |
| Image | — | URL, base64, Uint8Array | — | — | Sent as image parts in messages; counts as input tokens |
| — | URL, base64, Uint8Array | — | — | Sent as file parts in messages; counts as input tokens |
Provider options
Set AI Gateway routing options under providerOptions.gateway. For provider-specific options, pass them under the provider’s namespace as documented by the AI SDK.
Learn more in the AI SDK xai provider docs.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', prompt: 'Why is the sky blue?', providerOptions: { gateway: { only: ['xai', 'vertex'], }, }, });
console.log(result.text);}
main().catch(console.error);These AI Gateway routing options apply to every model. Provider-specific options pass through under the provider’s own namespace (for example providerOptions.anthropic) exactly as documented by the AI SDK.
| Parameter | Type | Required | Description |
|---|---|---|---|
providerOptions.gateway.only | string[] | No | Restrict routing to these provider slugs. Requests fail over only within the listed providers. |
providerOptions.gateway.order | string[] | No | Preferred provider order. Listed providers are tried first; unlisted providers remain available as fallbacks. |
providerOptions.gateway.sort | 'cost' | 'ttft' | 'tps' | No | Rank candidate providers by price, time to first token, or tokens per second instead of the default routing order. |
providerOptions.gateway.zeroDataRetention | boolean | No | Route only to providers with a zero-data-retention policy for this model. |
Routing across providers
AI Gateway serves the same model through multiple providers and fails over automatically. order expresses a preference while keeping every provider eligible; only is a hard allowlist — if none of the listed providers are available the request fails instead of falling back.
Options under a provider's own namespace (for example providerOptions.anthropic) are forwarded to that provider with the request. Providers ignore option namespaces that don't apply to them, so it is safe to set provider options alongside gateway routing options.
Reasoning
AI Gateway bridges reasoning across every API format. The AI SDK exposes a provider-agnostic top-level reasoning level (none, minimal, low, medium, high, or xhigh); the Chat Completions and Responses formats take the same effort under reasoning.effort; and the Anthropic Messages format uses a native thinking token budget. Whichever you send, the gateway maps it to the target model’s native configuration, converting between effort levels and token budgets as needed. Reasoning-related settings under providerOptions take full precedence over the top-level reasoning value and are never merged. Reasoning tokens typically count toward your output-token usage, though how they’re reported and billed varies by provider.
Learn more in the AI Gateway reasoning guide.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', prompt: 'Explain the Monty Hall problem step by step.', reasoning: 'high', });
console.log(result.text);}
main().catch(console.error);Image input
Send images alongside text as message parts. Images count as input tokens.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', messages: [ { role: 'user', content: [ { type: 'text', text: 'Describe this image.' }, { type: 'image', image: 'https://example.com/photo.jpg' }, ], }, ], });
console.log(result.text);}
main().catch(console.error);PDF input
Attach PDFs as file parts. Their contents count as input tokens.
import { generateText } from 'ai';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', messages: [ { role: 'user', content: [ { type: 'text', text: 'Summarize this document.' }, { type: 'file', mediaType: 'application/pdf', data: 'https://example.com/document.pdf', }, ], }, ], });
console.log(result.text);}
main().catch(console.error);Tool calling
Expose tools the model can call. Define each tool’s inputs with a Zod schema.
import { generateText, tool } from 'ai';import { z } from 'zod';import 'dotenv/config';
async function main() { const result = await generateText({ model: 'spacexai/grok-4.20-reasoning', prompt: 'What is the weather in San Francisco?', tools: { getWeather: tool({ description: 'Get the current weather for a location', inputSchema: z.object({ location: z.string() }), execute: async ({ location }) => ({ location, temperatureC: 18 }), }), }, });
console.log(result.text);}
main().catch(console.error);Copy link to headingMore models by SpaceXAI
| Model |
|---|
| 500K | $2/M+1 more | $6/M+1 more | Read$0.50/M | $5/K | +1 | | 08/12/2026 | |||||||
| 500K | $2/M+1 more | $6/M+1 more | Read$0.30/M | $5/K | +3 | | 07/08/2026 | |||||||
| 1M | $1.25/M+1 more | $2.50/M+1 more | Read$0.20/M | $5/K | +3 |  | 04/30/2026 | |||||||
| 2M | $1.25/M+1 more | $2.50/M+1 more | Read$0.20/M | $5/K | +2 | | 03/10/2026 | |||||||
| 1M | $0.20/M | $0.50/M | Read$0.05/M | — | +2 | | 11/19/2025 | |||||||
| 1M | $0.20/M | $0.50/M | Read$0.05/M | — | +1 | | 11/19/2025 |
Copy link to headingAbout Grok 4.20 Reasoning
Grok 4.20 Reasoning was released March 10, 2026 as the reasoning-enabled variant of SpaceXAI's Grok 4.20 beta generation. It supports extended thinking for complex problem-solving tasks, generating chain-of-thought reasoning traces before producing final answers. The model maintains the low hallucination rates and strict prompt adherence from the Grok 4.20 foundation.
The reasoning capability improves accuracy on tasks that benefit from structured thinking: mathematical problem solving, code debugging, logical analysis, and multi-step planning. Reasoning traces are visible in the API response, providing transparency you can use for debugging and auditing.
This model is currently in beta.
Copy link to headingWhat To Consider When Choosing a Provider
- Configuration: Grok 4.20 Reasoning is in beta. Expect potential changes before general availability.
- Configuration: Extended thinking adds tokens and latency to each response. For tasks that don't benefit from structured reasoning, the non-reasoning variant is faster and cheaper.
- Zero Data Retention: Zero Data Retention is available for this model. It is offered on a per-provider and model basis. See the documentation for details.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
Copy link to headingWhen to Use Grok 4.20 Reasoning
Best for
- Complex problem solving: Requiring multi-step reasoning and extended thinking
- Mathematical and scientific analysis: Structured chain-of-thought improves accuracy
- Code debugging and review: That benefits from step-by-step logical analysis
- High-stakes decisions: Low hallucination rates and traceable reasoning are critical
- Research and analysis tasks: Operating over large document collections within the context of 2M tokens
Consider alternatives when
- Speed-focused tasks: The Grok 4.20 Non-Reasoning variant delivers faster responses at lower cost
- Multi-agent orchestration: The Grok 4.20 Multi-Agent variant is purpose-built for agent collaboration
- Stable production deployments: Beta models introduce risk. Use Grok 4.1 Fast Reasoning or the full Grok 4 instead
- Simple direct-response tasks: Reasoning overhead adds cost without improving quality
Copy link to headingConclusion
Grok 4.20 Reasoning brings extended thinking to the Grok 4.20 beta generation. Its combination of chain-of-thought reasoning, low hallucination rates, and strict prompt adherence makes it suitable for complex analytical tasks where accuracy and transparency matter. Consider the beta status when planning production use.
Copy link to headingFrequently Asked Questions
What does 'reasoning' mean for Grok 4.20 Reasoning?
Grok 4.20 Reasoning generates chain-of-thought reasoning traces before producing final answers. This extended thinking improves accuracy on complex tasks at the cost of additional latency and tokens.
What is the context window for Grok 4.20 Reasoning?
2M tokens.
Is Grok 4.20 Reasoning in beta?
Yes. Grok 4.20 Reasoning is currently in beta. Behavior, pricing, or availability may change before general availability.
What does Grok 4.20 Reasoning cost?
Rates are listed on this page. They reflect the providers routing through AI Gateway and shift when providers update their pricing.
How do I authenticate with Grok 4.20 Reasoning through Vercel AI Gateway?
Use your Vercel AI Gateway API key with
spacexai/grok-4.20-reasoningas the model identifier. AI Gateway manages routing and authentication automatically.Can I see the reasoning traces?
Yes. Chain-of-thought traces are included in the API response. You can inspect and log them for debugging and auditing.
Does Vercel AI Gateway support Zero Data Retention for Grok 4.20 Reasoning?
Yes, Zero Data Retention is available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.