Rheo

Rheo is a mobile experimentation platform for building and revising in-app journeys from a visual canvas. It is most suitable for indie developers and growth teams focused on onboarding, monetization, and retention flows. Native rendering and immediate publishing are strong advantages, while audience caps and currently limited SDK coverage should determine whether it fits your stack.

Overview

Rheo lets teams design, test, and iterate app flows without waiting for App Store reviews. Its canvas covers onboarding, paywalls, win-back journeys, and upsells, with branching and targeting for different audience paths. After the SDK is integrated, a published flow can be picked up immediately, shortening the loop between a change and its appearance in the app.

The product is aimed at fast-moving indie developers, with higher plans addressing growth teams and enterprise customers. It supports iOS and Android apps, and the supported SDK is React Native. Swift, Flutter, and Kotlin support are marked as coming soon, so teams on those stacks should treat the current integration choice as a significant limitation.

Key features

The visual builder combines interactive prototypes, reusable flow templates, and version history. Those features are useful when a team needs to sketch a journey, compare revisions, or return to an earlier version rather than manage every change as a separate release.

Experimentation supports holdouts and variants across flow structure, copy, and timing. Rheo reports conversion and revenue results, while its dashboard measures flow completion and supplies funnel and cohort views. This gives growth teams a way to connect a specific journey change with downstream outcomes. The free plan has no experiments, however, so variant testing starts with a paid subscription.

Rheo says flow inputs, layouts, animations, and system moments render natively on iOS and Android instead of inside a WebView. That approach is better suited to product teams that need app-native presentation. Named integrations include RevenueCat, AppsFlyer, Adjust, and Superwall; the developer guide specifically covers RevenueCat and Superwall paywall nodes and AppsFlyer attribution.

Rheo Engage adds broadcasts and automations, using the customer's own SES, Resend, Postmark, or SendGrid account. The privacy policy describes administrative, technical, and organizational safeguards, while acknowledging that absolute security cannot be guaranteed. Rheo says it does not sell personal information or store full payment card numbers. OAuth tokens and passwords remain with the host app and are omitted from Rheo terminal snapshots and analytics field maps.

Pricing

The freemium structure makes Rheo easy to start, but the free tier is primarily for a small single-app setup rather than experimentation.

Exceeding the included MAU quota pauses the SDK until the next month or a plan upgrade. On Indie, sending pauses after 2,000 marketing emails; Grow and Scale instead charge for excess sends. The one-seat Indie limit and absence of experiments make it a poor choice for collaborative optimization, while Grow is the first practical tier for a testing team.

Platforms

Rheo supports iOS, Android, and React Native. Native rendering is offered for iOS and Android flows, but teams building with Swift, Flutter, or Kotlin must wait for those SDKs to arrive.

Who it's for

Choose Rheo if your team needs to change onboarding, paywalls, win-back, or upsell journeys quickly and evaluate them with conversion, revenue, funnel, and cohort measures. Indie developers can use the free tier for a small app and modest email automation; teams that need experiments, more seats, or higher MAU capacity should budget for Grow or Scale. Enterprise buyers gain implementation support, SSO, and a custom SLA, making that tier the appropriate route for contractual requirements.

Pros and cons

Pros

• Native flow presentation: Rheo says layouts, animations, inputs, and system moments render natively instead of through a WebView.
• Focused experimentation: Holdouts and variants cover structure, copy, and timing, with conversion and revenue review.
• Useful growth integrations: RevenueCat, Superwall, AppsFlyer, and Adjust connect monetization and attribution workflows.
• Immediate publishing: Integrated SDKs can pick up flows after they are published from the canvas.

Cons

• Free tier excludes testing: Indie has no experiments and only one seat.
• Hard audience stops: Exceeding MAU pauses the SDK until renewal of the monthly allowance or an upgrade.
• SDK coverage is narrow today: React Native is supported, while Swift, Flutter, and Kotlin are still forthcoming.
• Email overages add cost: Grow and Scale charge $1 per 1,000 messages beyond their monthly allocations.

Alternatives

User Flow Software is the broader category starting point when you want to compare flow-design tools rather than commit to Rheo's mobile experimentation approach.

FlowMapp is a better fit for web, desktop, or Linux planning, with a free one-project tier and a $15 monthly Pro plan; it does not match Rheo's stated mobile flow experimentation focus.

Marvel suits teams wanting cross-platform prototyping, including web and API support, with a free one-user project and a $12 monthly Pro plan billed yearly.

Software Ideas Modeler is the alternative for UML and diagram work, including free non-commercial use, rather than mobile conversion experiments.

Zeplin Flows is preferable when design handoff and screen organization matter most; its free plan allows one project and 100 screens but has no Flow Boards.

FlowSnap offers a free canvas for up to three projects with watermarked PNG export.

BenchCanvas is aimed at browser-based flow review with comments, annotations, AI analyses, and export options.

Cairn is a macOS choice for scenario mapping, with a free project limited to two scenarios.

EVONX is a web-based option centered on repository scans, connected repositories, previews, and workspace credits.

Verdict

Rheo is a strong choice for React Native teams that need native-looking mobile flows, rapid publishing, and structured experimentation around conversion journeys. Its main reason to look elsewhere is equally clear: teams on Swift, Flutter, or Kotlin, or apps likely to exceed the MAU limits, face a constrained rollout until broader SDK support or a larger contracted allowance is available.