Quick answer
UXPin - UXPin wins for most builders because its free tier is closer to an ongoing starter plan, while Proto.io is really a short trial with a small post-trial ceiling.
How the free tiers compare
These two products both help you prototype, but they serve different moments in a workflow. Proto.io gives you a brief, no-card trial that is useful for testing the editor and sharing a tiny prototype, then moves into a set of low-cost flat plans. It is straightforward if you want a simple handoff-friendly mockup tool with clear project and user caps. UXPin’s free tier is more of an entry point into a broader product that mixes prototyping with coded libraries, AI credits, and design-system-aware workflows. Its free tier is limited to 2 prototypes and 7 days of history, but the paid path starts at the same $29/month as Proto.io’s cheapest plan and adds more room to grow in both prototype count and workflow sophistication. If you need to keep using the product after evaluation, UXPin is the more usable free starting point.
Proto.io vs UXPin free tier, side by side
| Proto.ioFTV 42 | UXPinFTV 59 | |
|---|---|---|
| Free access shapeA is time-limited; B is an ongoing capped free tier. | 15-day trial, then limited free account | Free tier |
| Free projects / prototypesDifferent units, but both are tightly capped. | 1 active project | Up to 2 prototypes |
| Free screens / library sizeUXPin’s free tier includes a starter coded library rather than a screen cap. | 5 prototype screens | MUI with 20 components |
| Free storage / historyApples-to-oranges limits, but both constrain small-team use. | 10 MB storage | 7 days of version history |
| Free reviewers / sharingProto.io’s sharing is more limited on the free offer. | No additional reviewers | Password-protected preview |
| Free card requirementBoth fields are explicitly provided. | No credit card required | No credit card required |
After you outgrow the free tier
Proto.io uses flat monthly pricing after the trial, starting at $29/month and scaling by users and active projects up to $199/month. UXPin also starts at $29/month, then moves to $40/month for Growth, with Enterprise by custom quote. For most small teams, the cost diverges when you need more collaboration features and higher prototype counts: UXPin adds more workflow depth at the $40 tier, while Proto.io stays focused on bigger project and user limits at each flat step. Neither product provides usage-based rates here, so there are no per-usage cost calculations to work from.
When to pick each one
Pick Proto.io when…
- You want to try a prototyping tool quickly and only need a short evaluation window.
- You are making a small clickable demo with up to 5 screens and 1 active project.
- You mainly need exports to HTML, PNG, or PDF for sharing with stakeholders.
- You want a simple flat-priced upgrade path with user and project caps that are easy to understand.
Pick UXPin when…
- You want a free tier you can keep using instead of a short trial.
- You need interactive prototypes with states, variables, or conditional logic.
- You want built-in coded libraries and design-system-aware workflows.
- You expect to move into features like Storybook integration, SSO, or longer version history later.
- You are comparing paid entry plans and want a $29/month starting point that unlocks unlimited prototypes.
Bottom line
For the most common builder use case, UXPin is the better free-tier pick because you can keep working in it without hitting a trial wall, and the paid path stays close to the entry price while adding more serious prototyping and workflow features. Proto.io makes sense if you mainly want a short evaluation of a simpler prototype tool and are comfortable with a small, capped handoff-oriented plan afterward. If you are choosing one to start with and may outgrow it, UXPin is the safer default.
Read the full listings: Proto.io and UXPin. Scores use the FTV methodology at /ftv. Browse more head-to-heads on /compare, or see the top-ranked free tiers on /top.