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Grok 4.3

xAI · Grok

xAI's lower-cost 1M-context route for general reasoning and agentic work, now sitting behind the Grok 4.5 flagship.

Part of Grok family · Other versions: Grok 4.5 , Grok Build 0.1 , Grok 4.20 , Grok 4.1 Fast , Grok Code Fast 1 , Grok 4
Type
multimodal
Context
1M tokens
Max Output
N/A
Status
current
Input
$1.25/1M tok
Output
$2.5/1M tok
API Access
Yes
License
proprietary
reasoning tool-use agentic multimodal long-context cost-efficient coding
Released April 2026 · Updated July 10, 2026

Overview

Freshness note: Model capabilities, limits, and pricing can change quickly. This profile is a point-in-time snapshot last verified on July 10, 2026.

Grok 4.3 is xAI’s lower-cost current route for general reasoning, non-reasoning, and agentic workloads. It first appeared in the consumer Grok product in mid-April 2026 and rolled out across xAI’s API and partner integrations through the end of that month. Its 1M context window is larger than the newer Grok 4.5 flagship’s 500K window, while its published token rates are lower.

Grok 4.3 remains the migration target for retired Grok 4, Grok 4.1 Fast, and Grok 3 callers. Old Grok Code Fast configurations map to Grok Build 0.1. For new difficult coding and knowledge-work agents, compare both routes with Grok 4.5 rather than assuming the retirement-era migration target is still the strongest option.

Capabilities

Grok 4.3 is a reasoning model with extended chain-of-thought and a 1M-token context window. xAI emphasizes three capability areas in its current materials:

  • Agentic reasoning across long-context tool loops, including web search, X search, code execution, connectors, and MCP-style tool flows.
  • Multimodal input: text and image are first-class, and recent updates extended Grok’s input handling toward richer document and video understanding in product surfaces.
  • Document and presentation synthesis in product mode, with downloadable PDFs, spreadsheets, and slide decks coming out of conversation rather than as a separate generation step.
  • General coding help inside broader assistant workflows, while demanding coding agents should also evaluate Grok 4.5.

For developers, the practical value is now route diversity. Grok 4.3 offers a larger context window and lower token price than 4.5, while 4.5 is the newer flagship for coding, technical reasoning, and agentic knowledge work.

Technical Details

xAI’s developer documentation lists Grok 4.3 with a 1M-token context window, configurable reasoning, and support for non-reasoning mode. The migration guide documents four reasoning effort levels for this transition: none, low, medium, and high. The guide recommends Grok 4.3 directly for reasoning workloads and Grok 4.3 with reasoning_effort set to none for older non-reasoning Grok 4.1 Fast callers.

xAI does not publish a separate maximum output-token value on the current model page. Here, maxOutput: 0 means “not separately published,” not a literal output limit. Applications should set explicit per-request output and timeout budgets.

Pricing & Access

Listed API pricing (per 1M tokens):

  • Input: $1.25
  • Output: $2.50

This is substantially cheaper than the published Grok 4.5 rates of $2 input and $6 output per million tokens. Cached input is discounted, tool calls are billed separately, and very large requests can use different pricing.

Access options:

  • xAI API
  • Grok consumer apps and X ecosystem surfaces
  • xAI enterprise integrations
  • Partner inference and gateway providers where enabled

Best Use Cases

Use Grok 4.3 for:

  • General agentic and reasoning workloads where price and the 1M context window matter.
  • Long-context retrieval-heavy assistants that previously hit Grok 4 only for difficulty reasons.
  • Tool-using research workflows that benefit from xAI search, code execution, and MCP integrations.
  • Cost-sensitive production traffic that still needs strong reasoning behavior.
  • Assistant workflows that include some coding help but do not need the newer Grok 4.5 flagship.

Use reasoning effort deliberately instead of routing new work through deprecated slugs. none is the migration path for old non-reasoning callers, low is the default redirect for old reasoning slugs, and medium or high should be set explicitly when a workload benefits from deeper reasoning. For old grok-code-fast-1 style agentic coding workloads, use Grok Build 0.1 explicitly.

Comparisons

  • Grok 4 (xAI): Deprecated older reasoning route; 4.3 is the recommended replacement and post-retirement redirect target.
  • Grok 4.5 (xAI): Newer flagship for coding and agentic knowledge work, with a smaller 500K context window and higher token price.
  • Grok Build 0.1 (xAI): Cheaper public-beta coding API route and the xAI migration target for old Grok Code Fast workloads.
  • Claude Opus 4.7 (Anthropic): More expensive premium frontier route with stronger governance and platform breadth, while Grok 4.3 leans on tighter xAI ecosystem alignment and aggressive pricing.
  • GPT-5.5 (OpenAI): Comparable generalist flagship, with broader enterprise documentation and tooling ecosystem, while Grok 4.3 is the more cost-competitive tool-using reasoning option.