Cross-platform app agencies: shared code, dual-store shipping

Choose cross-platform when both stores matter early, your UX is mostly shared product flows (not platform-exclusive gestures or bleeding-edge APIs), and one team will own the client codebase. Stay native when performance, offline sync, camera/AR, or OS-deep features would force large native bridges anyway — or when you already staff separate Swift and Kotlin teams. A good agency recommends against your constraints; a weak one sells one stack for every brief.

Usually not. You often save duplicate UI and a chunk of client feature work versus two native apps, but discovery, design, backend, integrations, QA, and store submission still cost. Plan for meaningful shared-surface savings plus contingency for native modules and platform polish — not a 50% sticker price.

Pick from hiring plan and product constraints. React Native often fits TypeScript-heavy orgs that want web-adjacent talent; Flutter often fits greenfield UIs where consistent cross-platform visuals matter more than sharing code with a web app. Demand shipped dual-store proof on the proposed stack and a clear plan for native modules when shared layers run out.

Agencies typically own client architecture, shared UI implementation, CI for both platforms, and store-ready builds per SOW. You should keep product priorities, store accounts, cloud/API keys, analytics, and long-term repo ownership under your org. Write who handles review rejections, certificates, and post-launch hotfixes into the contract so offboarding is not a hostage situation.

Name min OS versions, must-have device capabilities, MVP vs later scope, backend ownership, analytics/crash tooling, and who submits to App Store and Play. Include offline, payments, and auth edge cases explicitly. Vague “ship on both platforms” briefs produce optimistic timelines and Android-as-afterthought delivery.