Case study — Marketplace

Menstruflow (ONEflow) —
Wearable TENS Device App

Period pain stops too many people in their tracks, and Menstruflow set out to change that. The Berlin-based, woman-founded startup created ONEflow — a discreet, wearable TENS device that eases period pain and endometriosis symptoms with gentle electrical impulses instead of medication. Krify built the mobile app that brings it to life: a Flutter app for iOS and Android that pairs with the ONEflow device over Bluetooth and puts full control — modes, intensity and settings — right in the user’s hand.

Project Snapshot

Client

Menstruflow (Berlin, Germany)

Industry

FemTech / health & wellness — period care

Platforms

Android, iOS & Web

Product

ONEflow — wearable TENS device for drug-free period pain relief

Services

Wearable & Bluetooth App Development · UI/UX · MVP Development

Timeline

~1–1.5 months (MVP)

The Challenge

Menstruflow needed an app that could do two things at once: control a physical device reliably over Bluetooth, and look polished enough to win over stakeholders — many of whom are not technical. As an MVP, it had to prove the concept and make a strong first impression.

Talk to the hardware: The app had to pair with the ONEflow device over Bluetooth and control it in real time.

Make it effortless: People adjust intensity and modes throughout the day, so the controls had to be simple and immediate.

Impress non-technical stakeholders: A refined, professional interface — down to the preloader — mattered as much as the functionality.

Leave room to grow: The MVP had to be a foundation for future features like Shopify integration, a period calendar and gamification.

Our Solution

Krify built a clean, single-purpose app in Flutter — one codebase for iOS and Android — focused on making device control feel instant and reassuring.

Reliable Bluetooth pairing

Connect to the ONEflow device in a couple of taps, with a clear green indicator confirming it is on.

Everything at a glance

Battery status and current settings are shown up front, with a settings overlay for personalising the experience.

Built as a foundation

A polished MVP designed to extend into Shopify, a period calendar and gamification down the line.

Intuitive intensity control

Each mode starts gently at level 1 and scales up to 20 with a simple thumb control.

Flexible sign-in

Key Features

Bluetooth device pairing

with the ONEflow TENS device.

Multiple impulse modes

to choose from.

Intensity control (levels 1–20)

via a simple thumb control

Green on-indicator

for at-a-glance reassurance that the device is active.

Battery and settings display

showing status and current mode up front.

Customisable settings overlay

to personalise the experience.

Shopify and Google login

plus guest access.

Polished MVP interface

with a professional preloader.

Product Experience

One design system across the marketplace experience.

Technology Behind the Build

Built on a reliable mobile and web foundation.

Mobile apps

Flutter

Web & back end

Node Js

Work With Krify

Krify is a mobile app development company that connects apps to the real world:

Specialists in wearable and Bluetooth (IoT) app development, linking mobile apps to physical devices.

Experienced across FemTech and health & wellness products, built with care and discretion.

Cross-platform Flutter development — iOS and Android from a single codebase.

Have a device or app idea of your own? We will build your MVP and grow it with you.

Menstruflow (ONEflow) — Wearable TENS Device App