Free open source alternative app list of Proto.io :

Figma

Figma is the leading collaborative design tool for building meaningful products. Seamlessly design, prototype, develop, and collect feedback in a single platform.

FreemiumWindowsmacOSAndroidiOS

Zeplin

Bring harmony to design delivery. Version control, user flows, design systems, sign-offs, and more. Zeplin unites your product team to accelerate design delivery at scale.

FreemiumWindowsmacOS

Origami Studio 3

Origami Studio is a free design tool created by Meta and available for Mac. It allows designers to rapidly build and share interactive interfaces. With a new canvas interface, dynamic layout, Figma & Sketch support and a ton of peformance improvements and new patches.

FreemacOS

Pixso

Pixso is an all-in-one design collaboration tool that helps production and research teams create prototypes, ui/ux design, visual design, and low-code delivery for a more streamlined work experience, making team collaboration more efficient. sketch and figma formats are supported.

FreemiumWindowsmacOSAndroid

Justinmind

Easily create web and mobile app prototypes and wireframes with Justinmind UI prototyping tool. It's FREE. Start prototyping now!

FreemiumWindowsmacOS

Marvel

The collaborative design platform. Wireframe, prototype, user test, design and inspect designs in one place, for free! Or create an integration with our API.

FreemiumWindowsmacOSAndroidiOS

UXPin

Design tool like no other. Prototypes that feel real, with powers of code components, logic, states, and design systems. Join for free!

FreemiumWindowsmacOS

Framer

Framer is where teams design and publish stunning sites. Use powerful yet familiar tools to create your ultimate website design. Import your designs from Figma.

FreemiumWindowsmacOS

Webflow

Create custom, responsive websites with the power of code — visually. Design and build your site with a flexible CMS and top-tier hosting. Try Webflow for free.

FreemiumWindowsmacOS

Others are looking for free open source alternatives of following apps:

AdGuard

AdGuard is a cross-platform ad blocker that filters web content and protects privacy.

AI & Machine Learning

Free open-source AI & machine learning tools.

Acorn 7

Acorn 7 is a Mac image editor for editing photos and creating graphics.

AdGuard DNS

AdGuard DNS is a DNS-based service that blocks ads, trackers, and malicious websites.

Adobe Premiere Pro

Adobe Premiere Pro is a professional video editing software for film, TV, and web.

Ad Blocker

Ad Blocker is a browser tool that removes intrusive ads and pop-ups from web pages.