What is Grok, exactly?
Grok is a family of large language models built by xAI, the AI lab Elon Musk founded in July 2023. The name is taken from Robert Heinlein's 1961 novel Stranger in a Strange Land, where "to grok" means to understand something so completely it becomes part of you. xAI's first public release, Grok-1, shipped in November 2023 as a mid-size model with an 8,192-token context. The family has grown fast since.
By the April 17, 2026 release of Grok 4.3 Beta, the lineup had scaled to a 2-million-token context window, a 16-agent "Heavy" multi-agent system, and native video input. That context is the largest of any Western closed-weight model — more than four times GPT-5's and ten times Claude Opus 4.6's public limits, according to xAI's public model docs.
The branding decisions matter. Where most labs tune hard toward caution, xAI tuned Grok toward directness and humor. Musk, at the July 2025 Grok 4 livestream, told viewers the model was designed to be "maximally truth-seeking, even when that is uncomfortable." Independent reviewers at Tom's Guide and Zapier consistently note Grok as the fastest-responding and least-hedged of the four frontier chatbots in 2026.
Every Grok generation, compared.
The six generations currently in public use, with context window, price, and availability. Numbers pulled from xAI docs, OpenRouter, and Artificial Analysis as of April 2026.
| Model | Released | Context | API price | Availability | Best for |
|---|---|---|---|---|---|
| Grok 2 | Aug 2024 | 128K | legacy | Deprecated on xAI API | Historical reference — early xAI benchmark baseline |
| Grok 3 | Feb 2025 | 131K | $3.00 / M in | xAI API, OpenRouter, ZeroTwo | Proven workhorse — everyday chat, coding, general analysis |
| Grok 4 | Jul 2025 | 256K | $3.00 / M in · $15 / M out | xAI API, OpenRouter, ZeroTwo, X Premium+ | Complex reasoning, long-form analysis, flagship quality |
| Grok 4.1 Fast | Nov 2025 | 2,000K | $0.20 / M in · $0.50 / M out | xAI API, OpenRouter, ZeroTwo | Cheapest frontier tier + longest context — RAG, agents, bulk jobs |
| Grok 4.20 | Mar 2026 | 2,000K | $2.00 / M in · $6 / M out | xAI API, ZeroTwo | Healthcare/legal reasoning — Intelligence Index 49 (median 32) |
| Grok 4.3 Beta | Apr 2026 | 2,000K | SuperGrok Heavy ($300/mo) | xAI beta · rolling out mid-May 2026 | Native video input, downloadable PDF/slide generation |
Sources: xAI developer docs, OpenRouter model listings, Artificial Analysis benchmarks. Prices represent standard-tier API rates, not consumer plans.
How does Grok compare to ChatGPT, Claude, and Gemini?
Grok 4.1 Thinking currently holds the #1 slot on LMArena's Text leaderboard at 1483 Elo, narrowly ahead of Claude Opus 4.6 and GPT-5.4. That's a genuine shift: twelve months earlier Grok models didn't crack the top ten. On the Artificial Analysis Intelligence Index, Grok 4.20 scores 49 versus a 32 median for reasoning models at similar price points.
But leaderboards hide the texture. Claude Opus 4.6 still wins expert coding tasks — it scores 1606 Elo on expert-task evaluations and remains the engine behind Cursor, Windsurf, and Claude Code. GPT-5.4 is the first model to beat humans on computer-use benchmarks and ships the deepest integration catalog. Gemini 2.5 Pro and Gemini 3 Pro remain the multimodal and math standouts.
The practical rule four years into the post-GPT-4 era: Grok for real-time context, speed, and contrarian framing; Claude for careful code and long-form writing; GPT-5 for general-purpose work with tools and integrations; Gemini for whole-document multimodal reasoning. For older xAI generations, see our Grok 3 deep-dive. Inside ZeroTwo's multi-model chat, you don't have to choose — run the same prompt against two models and compare answers side by side.
How to prompt Grok well.
A four-step recipe that leans into Grok's strengths — directness, live context, contrarian framing — and hedges its weakness, which is the same directness overshooting on ambiguous inputs.
- 1 · Frame
Tell Grok the domain and the stakes: 'You're helping a B2B founder decide on infra. Be direct — no hedging.'
- 2 · Anchor
Give it live context Grok does well with: link to an X post, paste a news excerpt, or drop a long doc (use Grok 4.1 Fast for 2M-token files).
- 3 · Pressure-test
Ask for the strongest counter-argument, then the one thing most people get wrong. Grok leans into contrarian framing more than GPT or Claude.
- 4 · Cross-check
Send the same prompt to Claude or GPT-5 in ZeroTwo's side-by-side view. Where they converge is usually real; where they diverge is where to dig.
How to try Grok (without X Premium+).
Three paths. The fastest is ZeroTwo: sign in with Google or email, open the chat interface, pick any Grok model from the selector, and start prompting. The free trial includes Grok 4 and Grok 4.1 Fast; Pro unlocks every model including Grok 4.20 for $29.99/month — less than X Premium+, with Claude, GPT-5, and Gemini included.
The second path is grok.com, xAI's standalone product. It has a free daily-limited tier and mirrors Grok on X with native image generation. The third is the xAI API (or OpenRouter) if you're building — Grok 4.1 Fast at $0.20 per million input tokens is the cheapest frontier-class rate on the market.
For comparison shopping, see our deeper dives on using Grok free on ZeroTwo, the broader model catalog, and the ChatGPT-alternative landscape.
Key takeaways
- Grok is xAI's frontier model family — Grok 4.3 Beta is the latest, released April 17, 2026.
- Grok 4.1 Fast delivers a 2,000,000-token context at $0.20 per million input tokens — the cheapest frontier rate in the market.
- Grok 4.1 Thinking currently holds the #1 slot on LMArena's Text leaderboard at 1483 Elo.
- Grok's edge is real-time X data, a less-hedged tone, and the largest context window of any Western closed model.
- The fastest way to try Grok without an X Premium+ subscription is ZeroTwo, which bundles every Grok model alongside Claude, GPT-5, and Gemini.
- Use Grok for contrarian framing and live-context tasks; cross-check with Claude or GPT-5 for critical code and long-form writing.
Frequently asked about Grok.
Eight direct answers, sourced from xAI docs, LMArena, and Artificial Analysis.
What is Grok?
Grok is a family of large language models built by xAI, the AI company Elon Musk founded in 2023. The name comes from Robert Heinlein's 1961 novel Stranger in a Strange Land and means to understand something so deeply it becomes part of you. The Grok series now spans Grok 2, Grok 3, Grok 4, Grok 4.1 Fast, Grok 4.20, and the Grok 4.3 Beta released on April 17, 2026. Grok is notable for a 2-million-token context window on its latest generations, real-time access to posts on X, and a deliberately less-hedged personality than ChatGPT or Claude.
How does Grok compare to ChatGPT and Claude?
Each frontier model wins different tasks. Grok 4.1 Thinking currently holds the #1 Text leaderboard slot on LMArena with 1483 Elo, and Grok 4.20 scores 49 on the Artificial Analysis Intelligence Index versus a 32 median for reasoning models at its price point. Claude Opus 4.6 still leads on expert coding tasks and produces the most natural long-form prose. ChatGPT GPT-5.4 is the first model to beat humans at computer-use benchmarks and has the broadest integration ecosystem. Practical rule: Grok for real-time context and speed, Claude for code and careful writing, ChatGPT for general-purpose integrations.
What is the context window of Grok?
Grok 4.1 Fast, Grok 4.20, and Grok 4.3 Beta all ship a 2,000,000-token context window, the largest of any Western closed-weight model as of April 2026. Grok 3 and Grok 3 Mini run at 131,072 tokens, and Grok 4 sits at 256,000. At 2M tokens you can paste an entire codebase, a 1,500-page PDF, or several hours of transcripts into a single prompt without chunking.
How much does Grok cost?
Three tiers. API: Grok 4.1 Fast is the cheapest frontier rate in the market at $0.20 per million input tokens and $0.50 per million output — undercutting GPT-5 mini, Gemini Flash, and every Anthropic model while shipping a larger context than any of them. Consumer: X Premium+ starts at $22/month and includes Grok 4 plus image generation. SuperGrok Heavy, the tier with Grok 4.3 Beta and the 16-agent Heavy system, is $300/month. On ZeroTwo, Grok 4, Grok 4.1 Fast, Grok 4.20, and the older Grok 3 family are included free on the trial and unlimited on Pro ($29.99/mo) alongside 60+ other models.
Is Grok free to try?
Yes. The fastest free path is ZeroTwo: sign in, open chat, and pick any Grok model from the selector — no X Premium+ required. Grok also exposes a free tier on grok.com with limited daily messages, and xAI occasionally runs API credit programs. For heavy builders, OpenRouter resells Grok 4.1 Fast at the $0.20/M rate with pay-as-you-go billing.
What makes Grok different from other AI models?
Three things. First, real-time access to public X posts, which no other major model has — it pulls live discourse, not a stale crawl. Second, a deliberately less-moderated tone: Grok answers questions other chatbots refuse and adds humor where GPT/Claude would add disclaimers. Third, the 2M-token context window combined with aggressive API pricing, which makes it the only frontier model usable for million-token single-call workloads at commodity prices.
Can I try every Grok model in one place?
Yes — that's what ZeroTwo is for. Instead of juggling X Premium+, the xAI API, and OpenRouter, you can pick Grok 4, Grok 4.1 Fast, Grok 4.20, or Grok 3 from ZeroTwo's model selector and switch mid-conversation. You can also run Grok side-by-side with Claude Sonnet 4.6, GPT-5, and Gemini 3 Pro on the same prompt — the most reliable way to catch a model's blind spots.
Is Grok good for coding?
Grok 4 scores roughly 75% on SWE-bench Verified according to xAI's published numbers — competitive with GPT-5 and Claude Opus 4.6, though Claude still wins most real-world coding-agent benchmarks. The bigger practical win for coders is context: a 2M-token window means you can hand Grok 4.1 Fast an entire monorepo and ask for cross-file refactors without chunking. For day-to-day Copilot-style autocomplete, Claude and GPT-5 remain the default.
Who built Grok and where can I read the source?
Grok is built by xAI, a San Francisco–based research lab founded by Elon Musk in 2023. Primary sources: the official xAI docs at docs.x.ai list every current model, context size, and API price; xAI's release notes at grok.com/release-notes log version-by-version capability changes; and independent benchmarks from Artificial Analysis and LMArena publish elo scores and Intelligence Index numbers updated weekly.
The ZeroTwo editorial team tracks every frontier model release, runs benchmark comparisons across our 60+ model catalog, and updates these pages with primary-source numbers — never marketing copy.
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