Traveller app
BYSIM for iOS
Browse plans by country or region, buy, and install the eSIM from a QR code before the plane doors close.
- Installs
- Live since Oct 2024
- Category
- Travel
- Last update
- v6.9.2, June 2026
Case studies · Travel tech
BYSIM — data in 190+ countries, no plastic
A travel eSIM app on iOS and Android — pick a destination, buy a plan, install the eSIM from a QR code and land connected. Live since October 2024 and shipping ever since.
QRActivation, in seconds
2Plan types — unlimited or GB
24/7Human support, on WhatsApp
v6.9.2Current release
The problem
Where it started.
Roaming is a problem people only remember at the airport. Whatever the app does, it has to work in the ten minutes before a flight, on hotel wifi, on a phone the traveller has not thought about since the last trip — and it has to leave them genuinely connected when they land, not holding a receipt.
That makes an eSIM app unforgiving in a way a shopping app is not. The purchase is the easy half. The hard half is the install: a QR code, a carrier profile, a device that may or may not be unlocked, and a user in another country with no data to look up what went wrong. Every screen after payment exists to make that moment survivable.
In the stores
Three apps.
One order between them.
Each side of the marketplace got its own app, designed and built by the same team so the three never disagree about the state of an order. Install figures and dates are what the listings showed on August 13, 2026.
Traveller app
BYSIM for Android
The same product on the other store — same account, same eSIMs, same plans, installed the same way.
- Installs
- 1K+
- Category
- Entertainment
- Last update
- June 2026
The work
What we built.
Plans by where you are going
Browse by country or by region, with the popular destinations surfaced first, because most people are buying for one trip and not comparing a catalog.
Unlimited or by the gigabyte
Two plan shapes rather than a matrix — enough choice to fit a weekend or a month, not enough to stall the decision.
Install from a QR code
The eSIM profile installs in seconds from a code in the app, with video guides at the point of the install rather than in a help center.
A wallet of your eSIMs
Every plan bought sits in one place with its data balance, so a returning traveller tops up instead of starting over.
24/7 human support on WhatsApp
Because the moment it fails is the moment the user has no data to reach a web form, and WhatsApp is the app they still have.
Coverage in 190+ countries
Local networks negotiated through carrier partners, presented as one catalog the traveller never has to think about.
Gallery
A look at it.
Process
How we ran it.
- 01
Design for the airport
Every flow measured against a traveller in a hurry on a bad connection.
- 02
Make the install the product
The QR install, not the checkout, treated as the screen that decides everything.
- 03
Ship to both stores
iOS and Android released and maintained together.
- 04
Keep shipping
Live since October 2024 and past version 6 — this one never stopped.
Outcome
What changed.
20 monthsLive and still shipping
190+Countries a traveller can land in
v6.9.2Releases since October 2024
The install is the whole product. Anyone can take a payment; getting someone connected in a country they have just landed in, on a phone they have not touched since the last trip, is the hard part. That is the bit they built properly, and it is why we are still shipping two years later.
Wilming Chou, Founder, BYSIM
Stack
Built with.
- iOS
- Android
- eSIM provisioning
- QR install
- Card payments
- WhatsApp support
- Push notifications
Got a problem
shaped like this one?
Thirty minutes on your process. We'll tell you what we'd build first and what we'd leave alone.
Book the call→Or email hello@devjunction.co