fx (by Vercel) vs Grok Build CLI

Feature	fx (by Vercel)	Grok Build CLI

Tagline	Tiny, open, embeddable, native coding agent by Vercel.	Bring Grok into your terminal
Website	https://fx.sh	https://x.ai/cli
Language	zig	rust
Release Date	August 17, 2026	May 14, 2026
Last Updated	August 19, 2026	August 19, 2026
Provider Type	Independent	AI Lab
MCP Support	Yes	Yes
Multi-Agent Support	No	Yes
Git Integration	basic	deep
Multi-File Editing	Yes	Yes
Auto Test Running	No	Yes
Sandbox / Permissions	Yes	Yes
Image / Multimodal Input	Yes	Yes
Voice Mode	No	No
IDE Integration	None - Terminal only	None - Terminal only
Hooks / Extensions	No	Yes
Web Search	Yes	Yes
Local Model Support	Yes	Yes
Context Window	Model-dependent	Model-dependent
Terminal Bench		#9 · 20.3% ±3.1 (Terminal-Bench 4.0) ²
AA Coding Agent Index	-	47% · Grok 4.6 (xhigh)
Supported Models	All Vercel AI Gateway supported models, including OpenAI, Anthropic, Google, DeepSeek, z.AI, Moonshot, etc	SuperGrok Heavy, Grok 4.5, 4.20, Grok 4, Grok Build 0.1, custom models including OpenAI compatible models
Supported Subscriptions	-	SuperGrok X Premium
Pricing Model	Free, BYOK, Usage Based	Subscription
Free Tier	No	Yes
Price Range	0 - $20 / mo / Custom (Vercel AI Gateway)	$0 (3 Day Trial) / $30 monthly (SuperGrok) / $300 monthly (SuperGrok Heavy)
Source Code Availability	Open Source (Apache-2.0)	Open Source (EULA)
Source Code	https://github.com/vercel-labs/fx	https://github.com/xai-org/grok-build
Development State	active	active