xAI's Grok 4.3 Lands on Amazon Bedrock With 1M-Token Context

Grok 4.3 is now available on Amazon Bedrock, marking xAI's formal debut as a model provider on AWS's managed AI platform. With this launch, xAI joins Amazon Bedrock as a model provider, giving developers more choice as they build generative AI applications across reasoning, agentic, and enterprise workflows. On the surface, it's a straightforward distribution deal. Under the hood, it's a window into a much larger strategic chess match.

What You're Actually Getting

Grok 4.3 is a reasoning-first model with always-on and configurable reasoning effort, offering strong tool use and instruction-following capabilities for building multi-step agents, along with token efficiency for high-volume inference. The model's headline numbers are competitive:

• A 1-million-token context window and support for configurable reasoning efforts: none, low, medium, or high.
• Pricing on Bedrock's on-demand tier comes in at $1.25 per million input tokens and $2.50 per million output tokens, with cached input at $0.20 per million.
• The context window sits at 1 million tokens with a maximum output of 30,000 tokens, which puts it in range for long-document workloads like contract review, case law research, and financial document analysis.
• Beyond text, the model supports native video input and can generate PDFs, spreadsheets, and slide decks , capabilities that push it toward enterprise automation use cases rather than simple chat.

Grok 4.3 runs on Mantle, a new inference engine in Amazon Bedrock designed for price performance, with support for tool calling, structured output, and response streaming. Mantle is worth understanding on its own: Project Mantle simplifies and expedites onboarding of new models onto Amazon Bedrock, provides highly performant and reliable serverless inference with sophisticated quality of service controls, unlocks higher default customer quotas with automated capacity management, and provides out-of-the-box compatibility with OpenAI API specifications. That last point matters a lot for migration , you can point your existing OpenAI SDK calls at Bedrock with minimal changes.