fx (by Vercel) vs. zerostack

Feature	fx (by Vercel)	zerostack

Tagline	Tiny, open, embeddable, native coding agent by Vercel.	Minimal Rust coding agent optimized for memory footprint
Website	https://fx.sh	https://gi-dellav.github.io/zerostack/
Language	zig	rust
Release Date	August 17, 2026	May 12, 2026
Last Updated	August 19, 2026	September 4, 2026
Provider Type	Independent	Independent
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	Zed (via ACP), Neovim (via CodeCompanion.nvim + ACP)
Hooks / Extensions	No	Yes
Web Search	Yes	Yes
Local Model Support	Yes	Yes
Context Window	Model-dependent	Model-dependent; auto-compaction
Supported Models	All Vercel AI Gateway supported models, including OpenAI, Anthropic, Google, DeepSeek, z.AI, Moonshot, etc	OpenRouter (default), OpenAI, Anthropic, Gemini, Ollama, plus unlimited custom OpenAI-compatible endpoints (vLLM, LiteLLM, enterprise gateways)
Pricing Model	Free, BYOK, Usage Based	Free, BYOK
Free Tier	No	Yes
Price Range	0 - $20 / mo / Custom (Vercel AI Gateway)	Free (BYOK)
Source Code Availability	Open Source (Apache-2.0)	Open Source (GPL-3.0)
Source Code	https://github.com/vercel-labs/fx	https://github.com/gi-dellav/zerostack
Development State	active	active