Overview

Fluid UI is a web-based workspace for turning mobile-app concepts into mockups and interactive prototypes. It suits designers and product teams that need to show how screens connect and gather feedback; its strongest case is combining prototyping, collaboration and review in one service, though user-license caps make the plan choice important.

Projects can be created, edited, previewed, shared and exported. The breadth of supported design systems and gesture-based interactions helps communicate both appearance and flow, while cloud saving keeps work accessible to collaborators.

Key features

Component libraries: More than 2,000 built-in components cover Material Design, iOS, Windows and wireframe libraries. That gives designers multiple starting points for mockups instead of requiring every screen element to be built from scratch.
Interactive prototypes: Taps, swipes, clicks and other gestures can link screens in web and mobile prototypes. Pop-in, fade-in, flip and show effects add motion to a walkthrough, useful for explaining transitions without implying a finished application.
Collaboration and review: Real-time collaborative prototyping works on cloud-saved projects. Reviewer mode supports shared click-throughs, chat, annotations and comments, and remote user-testing sessions are supported. This makes Fluid UI more useful for critique and feedback than a mockup tool limited to static screens.
Preview and support: The service runs in Firefox and Chrome, has an installable desktop client, and offers Android and iOS preview apps. Built-in live chat support is available 16 hours a day.
Data handling: Fluid UI says pages use 256-bit encryption for data sent to the service, and that it continuously saves projects, makes daily, weekly and monthly backups, and allows restoration from a save in the editor. Realex Payments processes and stores card details rather than Fluid UI’s own servers. Its servers run in a Rackspace US data center; the privacy notice describes Rackspace as GDPR compliant and says users can request account-data deletion by email.

Pricing

Fluid UI uses a freemium model, with a free lifetime account and paid plans billed monthly at the stated rates. The Free plan has no price stated. Its project, seat and feature limits are not given, so it is difficult to judge whether it will accommodate ongoing work before upgrading.

Solo — 8.25 USD per month: Five active projects, one user license and unlimited reviewers. This is the clearest fit for an individual who needs to share prototypes for feedback; reviewers do not consume the single editing license.
Pro — 19.08 USD per month: Ten projects, one user license, unlimited reviewers, and export, print and comment. It adds useful output and commenting options over Solo, but remains a single-user plan, so it is not the step up for a team that needs several editors.
Team — 41.58 USD per month: Unlimited projects, five users, unlimited reviewers, export, print and comment, plus real-time team collaboration. It fits small groups that need several licensed users and shared work, but the five-user allowance is still a fixed cap.

The paid plan descriptions give monthly billing rates; check the project and seat allowances against the way your group works before choosing.

Platforms

Fluid UI is web-based and runs in Firefox and Chrome, with an installable desktop client and Android and iOS preview apps. Its listed platform support also includes Linux, macOS and Windows, making it a broad option for teams working across desktop systems and mobile previews.

Who it's for

Fluid UI is aimed at designers, entrepreneurs, developers, product managers, professors and others who need to communicate ideas. Solo designers can use the one-license plans while sharing click-throughs with unlimited reviewers; small teams get real-time collaboration on Team, which includes five user licenses. It is less suitable for a group that needs more than five licensed collaborators on that plan, or for buyers who need project limits clearly defined on the free account before committing.

Pros and cons

Pro: Interactive gestures, page effects and more than 2,000 components help turn screen mockups into demonstrations of product flow.
Pro: Unlimited reviewers on each paid plan, together with chat, annotations and comments, supports feedback without using up editor seats.
Pro: Team combines unlimited projects with five licenses and real-time collaboration, a useful combination for a small group working across multiple concepts.
Con: Solo and Pro each include only one user license, so adding co-editors requires a different plan.
Con: The service’s servers are in the United States, a material consideration for organizations evaluating data location.

Alternatives

Fluid UI is one option among wireframing software, game UI design software, UI design tools and prototyping software. Consider Mockplus instead if its free Basic plan’s stated allowance of 10 users and 10 active projects better suits a larger no-cost group. Justinmind is another freemium alternative, with a free plan covering one project, unlimited screens and viewers, UI design and wireframing.

Draftium may suit web-focused work where a free plan with up to three prototypes and 50 generic templates is a better match. Frame0 is worth considering if you want a desktop-focused option across Windows, macOS and Linux. Visily is a web and extension alternative with a Starter plan that includes 300 AI credits per month. MockFlow offers a freemium option across extension, macOS, web and Windows; MockupTiger offers one across web, Windows, macOS and Linux. Mokkup.ai has a free-forever plan with one editable project and three screens per project.

Verdict

Choose Fluid UI if you want to move from mockup screens to interactive, shareable prototypes and keep review in the same workflow. Solo is the natural starting point for one editor, while Team makes more sense when several people need to collaborate. Look elsewhere if your group needs more than five licensed editors on the stated Team plan, or if you need clear free-tier caps before deciding.

	Fluid UI	Quickmock
Free plan	Yes	Yes
Free trial	Yes	No
Paid from	$8.25/mo	Free
Open source	No	No
Platforms	Android, iOS, Linux, macOS, Web, Windows	Android, api, extension, iOS, Linux, macOS, self-hosted, Web, Windows
Free plan	Yes	Yes
Platform	—	web

Fluid UI vs Quickmock

Fluid UI

Quickmock