Mockingbird is described as 'Online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application' and is a Wireframing tool in the development category. There are more than 50 alternatives to Mockingbird, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and iPhone apps. The best Mockingbird alternative is Penpot, which is both free and Open Source. Other great sites and apps similar to Mockingbird are LibreOffice - Draw, yEd Graph Editor, Dia and Pencil Project.
Lucidchart is a cloud-based platform that promotes teamwork through diagramming, collaboration, and data visualization. It serves millions worldwide, offering flowcharts, UML, real-time collaboration, Visio support, and browser access. Designed for innovation and understanding, it integrates easily into workflows.
Open-source design platform offering web-based and self-hosted workflows, code inspection in HTML and CSS, adaptive layouts with CSS Grid and Flex, real-time collaboration, auto layout features, reusable components, design tokens, layer support, plugins, and no tracking.
Draw lets you produce anything from a quick sketch to a complex plan, and gives you the means to communicate with graphics and diagrams. With a maximum page size of 300cm by 300cm, Draw is a an excellent package for producing technical drawings, general posters, and much else.
yEd is a powerful diagram editor that can be used to quickly create diagrams manually or import external data for analysis and auto-magically arrange even large data sets by just pressing a button. You can use yEd to quickly create flow charts, BPMN and UML diagrams...
Open-source diagram editor supporting Linux, Windows, Unix, and Mac OS X, with features for constructing entity relationship, UML, flowchart, and network diagrams, customizable with XML-defined shapes, extensibility, and a GTK+-based graphical user interface.
Pencil is a standalone app that lets you create diagrams or UI mockups. It doesn't have collaboration/multi-user features.
Lucidchart is a cloud-based platform that promotes teamwork through diagramming, collaboration, and data visualization. It serves millions worldwide, offering flowcharts, UML, real-time collaboration, Visio support, and browser access. Designed for innovation and understanding, it integrates easily into workflows.
PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams. The generator can be run anywhere within JVM and integrated with various application such as wiki, text editor, IDE, programming language, documentation generator, and others.
Low-fidelity UI wireframing tool simulating sketching experience, optimized for speed with Quick Add, built for collaboration, drag-n-drop simplicity, exportable wireframes to PNG/PDF, interactive prototypes via linking, hundreds of UI components, reusable symbols, and more.
Google Drawings, part of Google Drive, allows users to collaborate creating, sharing, and editing images or drawings. It can be used for creating charts, diagrams, designs, flow-charts, etc.
OmniGraffle can help you make eye-popping graphic documents—quickly—by providing powerful styling tools, keeping lines connected to shapes even when they’re moved, and magically organizing diagrams with just one click.
Feature-rich, open-source Wireflow offers a collaborative platform for online creation of complex user flow prototypes. Ideal for team work in UI design, wireframing, and mind mapping, promoting idea sharing in real-time environment aided by modern whiteboard features.
A streamlined web app that helps you create and collaborate in real-time on wireframes, mockups, diagrams and prototypes.
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Mockingbird is purely designed for mockups. Pencil only has a small feature base for generating web-mockups