Grok 4.1 Fast Reasoning was released in November 2025 as xAI's high-throughput reasoning model, pairing extended chain-of-thought with the 2 million token context window and fast inference of the Grok 4.1 Fast line. It generates reasoning before responding, improving accuracy on math, code, and multi-step logic while keeping practical throughput. Compared to the non-reasoning variant, it trades some latency for higher accuracy on harder tasks, making it a fit for problem-solving applications that need both capability and long context. It supports vision, tool use, structured outputs, and function calling across multimodal inputs. Reasoning can be toggled through the API, so the same model line can serve fast direct replies or deeper deliberation depending on the request. It was trained with long-horizon reinforcement learning focused on multi-turn, tool-using scenarios.
Grok 4.1 Fast Reasoning runs on 2 different routes through the Opper gateway. Compare residency, ZDR, and training posture at a glance β full data-handling detail per route below.
| Provider | Region | Zero data retention | Training | Input | Output |
|---|---|---|---|---|---|
| Google Cloud | Multi | Enterprise | No | $0.20 | $0.50 |
| Google Cloud | US | Enterprise | No | $0.20 | $0.50 |
Training posture across routes: No training on prompts by default.
Each route hosting Grok 4.1 Fast Reasoning has its own privacy posture, residency, and GDPR terms. Postures are maintained by Opper with a last-verification timestamp.
Zero data retention is available via Opper Enterprise contract. No training on customer data. US; SCCs; DPA available.
Zero data retention is available via Opper Enterprise contract. No training on customer data. US; SCCs; DPA available.
Independent benchmark scores β composite indices for reasoning, coding, and math, plus individual eval scores where available.
Call Grok 4.1 Fast Reasoning through the Opper gateway with one API key. Let your coding agent set it up, or call it directly β Opper is drop-in compatible with the OpenAI, Anthropic, and Google AI SDKs.
Copy this and paste it into your coding agent β Claude Code, Cursor, Codex, and more β and it'll wire up Opper for you.
import OpenAI from "openai";const client = new OpenAI({apiKey: process.env.OPPER_API_KEY,baseURL: "https://api.opper.ai/v3/compat",});const completion = await client.chat.completions.create({model: "vertexai/grok-4-1-fast-reasoning",messages: [{ role: "user", content: "Hello" }],});console.log(completion.choices[0].message.content);
Side-by-side on privacy, EU hosting, pricing, and benchmarks.
