fx vs Google Stitch: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of fx and Google Stitch — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
fx
Vercel Labs
Vercel Labs' tiny open-source coding agent — a ~6 MB native CLI written in Zig, built for speed, embeddability and Unix-style ergonomics.
Key features
- Tiny Native Binary: The whole agent ships as a roughly 6 MB executable designed for instant installation and for embedding in resource-constrained environments and agent sandboxes.
- Instant Time to Prompt: fx cold starts in about 10 microseconds and performs no unnecessary work or I/O before accepting user input, which matters for programmatic invocation.
- Minimal Memory Footprint: A single-digit-megabyte memory baseline lets you pack many concurrent instances onto one machine.
- Shell-Like Ergonomics: Scroll history is preserved by default and output is deliberately sparse, so the CLI composes like a Unix tool instead of taking over the terminal.
- Context Efficiency: A minimal system prompt and tool surface reduce token spend and improve time-to-first-token performance.
- WebAssembly Builds: Optimal fx.wasm builds from the Zig toolchain shrink the binary further and make the network stack pluggable, enabling the in-browser demo.
- Model and Provider Agnostic: Works with local models, LLM gateways, direct provider API access or existing subscriptions rather than locking you to one vendor.
- Extensible Small Core: Capabilities are added through skills, plugins and MCPs, following a Unix-like philosophy of a small core with composable extensions.
Best for
- Sandboxed Agent Execution: Ship a full coding agent inside a container or sandbox where a large runtime would not fit.
- Embedding in Larger Systems: Use fx as the agent harness inside your own product or internal platform rather than building a loop from scratch.
- CI and Scripted Automation: Invoke a coding agent from pipelines and scripts where fast cold starts and quiet output matter more than an interactive UI.
- Agent Harness Research: Experiment with system prompt and tool design on a deliberately minimal, readable Apache-2.0 codebase.
- Local-Model Coding: Run agentic coding against a locally hosted model without any dependency on a specific cloud provider.
- Browser-Based Demos and Playgrounds: Compile to WebAssembly and run the agent client-side with networking delegated to browser fetch.
Google Stitch
Google LLC
Generates UI designs for mobile and web from prompts, sketches, or images to speed design ideation and prototyping.
Key features
- Prompt-to-UI Generation: Produces UI screens for mobile and web from natural-language prompts, sketches, or images to accelerate ideation and mockup creation.
- Sketch and Image Import: Accepts user sketches or images as input and converts them into UI layouts and visual designs to jumpstart the design process.
- Gemini CLI Extension: Provides a Gemini CLI extension enabling natural-language interaction with a Stitch MCP server for generating UIs and managing requests from the terminal.
- MCP Server & Proxy Tooling: Offers an MCP (Managed Control Plane) workflow and proxy utilities to host a Stitch MCP server, route requests, and facilitate local development/testing.
- GCP Integration & Authentication: Integrates with Google Cloud tooling (gcloud) for authentication, Application Default Credentials, project selection, and IAM role setup required to enable the Stitch API.
- CLI-based Setup & Diagnostics: Includes command-line installers and setup commands (e.g., npx @_davideast/stitch-mcp init) that automate installation, enable APIs, configure credentials, and diagnose setup issues.
- Generates UI designs for mobile and web from prompts, sketches, or images
- Hosted Stitch web application for interactive design ideation
- Stitch MCP API for programmatic access and server integration
- Gemini CLI extension to interact with Stitch via natural language commands
- MCP proxy server capability for local/dev proxying of Stitch MCP
- CLI-driven setup and provisioning (npx init, gemini extensions install)
- Google Cloud authentication support (gcloud auth, Application Default Credentials)
- IAM-based access control requirements and project-level service enablement
Best for
- Rapid Design Ideation: Quickly generate multiple UI concepts from a brief or sketch to explore interface directions during early-stage product design.
- Sketch-to-Prototypes: Convert hand-drawn sketches or screenshots into digital UI screens that designers can refine and iterate on.
- Developer Handoff Automation: Produce consistent UI outputs that designers can export or hand off to developers along with configuration for Stitch MCP to streamline implementation.
- CLI-driven Design Workflows: Integrate UI generation into terminal-driven workflows using the Gemini CLI extension for teams that prefer code/CLI environments.
- Enterprise Self-hosting & Control: Deploy and run a Stitch MCP server with GCP integration and IAM controls to maintain access governance and combine Stitch with internal toolchains.
- Local Development & Testing: Use the MCP proxy and diagnostic commands to test Stitch-generated UIs and API interactions in local or staging environments before production rollout.
- Rapid design ideation and exploration of mobile/web UI concepts
- Convert sketches or screenshots into polished UI screens for prototyping
- Automated UI generation in developer workflows via CLI or API
- Integrating AI-driven UI generation into a Google Cloud-based toolchain
- Local development and testing using an MCP proxy server
- CI/CD automation to generate or refresh design assets programmatically