Compare AI models

Specifications
Context window
1M—
API pricing
Input price
$10.00—
Output price
$50.00—
Cached input price
$0.25—
Cheapest input
$10.00Amazon Bedrock—
Cheapest output
$50.00Amazon Bedrock—
Benchmarks
BullshitBench v2
77%50%
Humanity's Last Exam · with tools
65.6%35%
Overview
CompanyAnthropicSpaceXAI
Release dateSep 1 2026Apr 17 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Fable 5.1 leads Grok 4.3 Beta on 2 of the 2 benchmarks they both report (BullshitBench v2, Humanity's Last Exam). Only Claude Fable 5.1 has a verified first-party API price: $10.00 per million input tokens and $50.00 per million output tokens. No pay-as-you-go API rate is tracked for Grok 4.3 Beta. Grok 4.3 Beta shipped 137 days before Claude Fable 5.1, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

On BullshitBench v2, Claude Fable 5.1 leads at 77% vs Grok 4.3 Beta at 50%. On Humanity's Last Exam · with tools, Claude Fable 5.1 leads at 65.6% vs Grok 4.3 Beta at 35%.