Measured on Composite
This model has not carried enough traffic on Composite yet to publish a success rate, a latency figure or a traffic rank. The numbers appear here once it has.
AI model
SpaceXAI: Grok 4.3 (fast) (Reasoning)
x-ai/grok-4.3:fast-reasoning
SpaceXAI: Grok 4.3 (fast) (Reasoning) is a 1,000,000-token model served on Composite at $1.56 per million tokens in and $3.13 per million tokens out.
Try in PlaygroundSpecifications
| Model ID | x-ai/grok-4.3:fast-reasoning |
|---|---|
| Provider | xAI |
| Context window | 1,000,000 tokens |
| Accepts | text, image, file |
| Returns | text |
| Input price | $1.56 per million tokens |
| Output price | $3.13 per million tokens |
| Prompt caching | Supported — cached input is billed at the provider's cache rate, on credits and plans alike |
| Web search | $0.0063 per result |
| Thinking | Optional - see "SpaceXAI: Grok 4.3 (fast) (Reasoning) (Reasoning)" in the catalog to turn it on by default |
| Moderated | No |
| Cost on a monthly plan | About 13 plan credits per typical call (8k in, 1k out) |
| Routing endpoints | 1 |
Pricing
$1.56 per million tokens input · $3.13 per million tokens output
Credits pay the provider’s price plus 25%; cache hits cost less.
On a monthly plan, a typical call (8k tokens in, 1k out) uses about 13 plan credits, at the provider's own price.
Provider
xAI
Roleplay fit
Grok models lean toward a more direct, less filtered writing style than many alternatives.
Context behavior
With a 1,000,000-token context window, it can hold a long-running roleplay or a full lorebook in memory without losing earlier plot details, so it suits multi-session campaigns and character cards with heavy backstory.
Cost for regular use
It sits in the mid-range on price, a reasonable pick for regular roleplay use without going for the cheapest option available.
From the provider
Grok 4.3 is a reasoning model from SpaceXAI. It accepts text and image inputs with text output, and is suited for agentic workflows, instruction-following tasks, and applications requiring high factual...
Supplied by xAI, not written by Composite.
Related models
SpaceXAI: Grok 4.7 · SpaceXAI: Grok 4.6 · SpaceXAI: Grok 4.5