Penpot - The Open-Source design & prototyping platform

Collection of custom elements that appear hand drawn. Great for wireframes or a fun look.

The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.

Design and prototype customized UI, interaction, navigation, transition and animation for App Store ready Apps in Interface Builder with IBAnimatable.

Mockoon is the easiest and quickest way to run mock APIs locally. No remote deployment, no account required, open source.

🎨 React application prototyping tool for developers and designers 🏗️

🐣 vue GUI generator

🧪 Prototyping Tool for exporting React/Typescript Applications!

Turn Python scripts into handouts with Markdown and figures

DEPRECATED: Multiplatform GUI Prototyping/Wireframing

Quickly try out any Swift pod or framework in a playground

A Ruby DSL for prototyping card games.

✔️ Mock data for your prototypes and demos. Remote deployments to Zeit now.

Browser-based MDX editor

Business database for non-programmers. Universal UI, simple-code logic, automatic actions, access rules, logging, API and more. Quickly create a complex internal apps using the database as an interface.

Mmock is an HTTP mocking application for testing and fast prototyping

🚧 Build web pages with Vuse, the next-gen interactive page builder powered with Vue.js.

Charm: A Framework for Rapidly Prototyping Cryptosystems

IBM TJBot

PHONK is a coding playground for new and old Android devices