Overview

Fluid UI is a web-based mockup and prototyping tool for turning mobile app concepts into interactive demonstrations. It best suits designers and small product teams that need to share ideas and gather feedback. Its mix of prototyping and review tools is useful, though the one-user licenses on Solo and Pro limit how well those plans serve collaborators.

Projects can be created, edited, previewed, shared and exported. Taps, swipes and clicks make prototypes navigable, while built-in components and page effects help convey an interface’s intended look and behavior.

Key features

Component libraries: More than 2,000 components cover Material Design, iOS, Windows and wireframe libraries. That gives designers several starting points for mockups, rather than tying them to a single design system.
Interactive prototyping: Taps, swipes, clicks and other gestures can connect screens in web and mobile prototypes. Effects including pop in, fade in, flip and show add motion to a walkthrough, but the tool’s stated scope is mockups and prototypes rather than finished apps.
Collaboration and review: Cloud-saved work supports real-time collaborative prototyping. Reviewer mode adds shared click-throughs, chat, annotations and comments, and Fluid UI supports remote user-testing sessions. These features make feedback part of the workflow, though access for active collaborators depends on the plan’s user licenses.
Support and project safeguards: Built-in live chat is available 16 hours a day. Fluid UI says it continuously saves projects, backs them up daily, weekly and monthly, and lets users restore a save from the editor. It also says pages use 256-bit encryption for data sent to the service.
Access: The web service runs in Firefox and Chrome, with an installable desktop client and Android and iOS preview apps. Fluid UI lists Android, iOS, Linux, macOS, web and Windows as supported platforms.

Pricing

Fluid UI uses a freemium model, with a free lifetime account and paid plans starting at $8.25/mo. A free trial is offered. The Free plan has no published price and its project and user limits are not given here, so it is harder to judge how far it will take a working project.

Solo — 8.25 USD per month: Includes 5 active projects, 1 user license and unlimited reviewers. It suits a solo designer who needs room for several projects and wants to collect feedback without licensing each reviewer. The single user license makes it a poor fit for a team building together.
Pro — 19.08 USD per month: Includes 10 projects, 1 user license, unlimited reviewers, export, print and comment. It adds practical ways to share or deliver work beyond Solo, but retains the one-user limit; choose it for a solo workflow that needs those capabilities, not for multiple active makers.
Team — 41.58 USD per month: Includes unlimited projects, 5 users, unlimited reviewers, export, print, comment and real-time team collaboration. It is the clearest fit for a small team working together. Teams larger than five users would need another arrangement.

The paid plan summaries give monthly prices and feature limits but do not state billing renewal terms. Fluid UI says Realex Payments processes and stores card details; Fluid UI does not store them on its own servers. Its privacy notice places servers in a Rackspace US data center and says users may request account-data deletion by email.

Platforms

Fluid UI is web-based and works in Firefox and Chrome, with a desktop client and Android and iOS preview apps. Its supported-platform list also includes Linux, macOS and Windows. This combination gives teams several ways to access projects and preview mobile prototypes without making the product a native-only design tool.

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 lower-cost paid plans while keeping reviewer access broad; teams wanting real-time co-authoring are better served by Team’s five user licenses. It is less suitable for a larger group that needs more than five licensed users or for someone seeking only a static mockup tool.

Pros and cons

Pros: A library of more than 2,000 components spans four named design and wireframe systems, giving mockup work a broad set of starting points.
Pros: Interactive prototypes, animations, reviewer comments and remote testing support both demonstration and feedback in one workflow.
Pros: Unlimited reviewers across the paid plans let teams share click-throughs without using active-maker licenses for every reviewer.
Cons: Solo and Pro each include only one user license, so collaborative editing requires the more expensive Team plan.
Cons: Team includes five users; teams needing more licensed collaborators may outgrow its stated allowance.

Alternatives

Fluid UI is one option among Wireframing Software and Prototyping Software; readers focused on broader tool categories can also compare UI design tools or Game UI Design Software.

Justinmind is worth considering for a free starting point with one project, unlimited screens and viewers, plus UI design, wireframing and interactive input forms.
Mockplus offers a free Basic plan with 10 users and 10 active projects, making it a candidate for groups that want more free-plan capacity.
Grapholite is a paid option available on web, Windows, macOS, iOS and Android.
Mokkup.ai has a free plan with one editable project and three screens per project, a narrower starting point for someone who only needs a small amount of dashboard-design work.
Visily has a free Starter plan with 300 AI credits per month and limited boards and elements, while its Pro plan costs 14.00 USD per month and includes 3,000 AI credits per month.
Draftium offers a free plan for up to three prototypes with 50 generic templates and unlimited editing, useful for readers whose immediate need is a small set of template-based prototypes.
Uizard starts with a free plan capped at two projects and five screens per project, and includes three AI generations per month.
Wireflow is a free, open-source option that can be self-hosted and requires no sign-up.

Verdict

Choose Fluid UI if you need interactive mobile mockups, straightforward ways to collect reviewer feedback and, on Team, real-time collaboration for a small group. Its broad component libraries and review workflow are the strongest reasons to pick it. Look elsewhere if you need multiple active makers on a low-cost plan, more than five Team licenses, or clear free-plan capacity before committing work to the tool.

	Fluid UI	Pixso
Free plan	Yes	Yes
Free trial	Yes	Yes
Paid from	$8.25/mo	$4/mo
Open source	No	No
Platforms	Android, iOS, Linux, macOS, Web, Windows	Android, api, macOS, self-hosted, Web, Windows
Free plan	Yes	Yes
Design systems	Yes	—

Fluid UI vs Pixso

Fluid UI

Pixso