---
title: From altitude sickness to the app store with Expo Router, ElysiaJS, and Nativewind
authors: Josep Vidal
published: June 19, 2025
categories: Users, React Native
tags: Expo Router, NativeWind, ElysiaJS, DrizzleORM
---

Last summer I failed.

I set out to conquer my first 5,000m mountain. But at 4,000m, waiting for sunrise, altitude sickness hit me hard. I had to turn back. My group summited, I didn’t.

That failure stuck with me. So I started climbing more. Getting stronger. And as a software developer I decided to over-engineer a solution to track my summits.

That’s how **100cims** was born: a personal app that became a passion project.

## What Is 100cims?

100cims is a mobile app for mountain lovers. It lets users:

- Track mountain summits across challenges ( 🇺🇸 US top 150 mountains, 🇪🇸 Catalonia’s 100 cims, 🇫🇷 GR-20 Corsica, 🇪🇺 European Alps…).
- Earn scores based on mountain difficulty and elevation.
- See summit history with a visual collage of photos.
- View a public ranking and compare with friends.
- Create and join **hiking plans** with built-in **chat 💬.**

In under 4 months, 100cims has grown to over 200+ users with 1,000+ summits logged — all 100% organic.

- 🤖 [On Android](https://play.google.com/store/apps/details?id=app.x100cims.x100cims).
- 🍏 [On iOS](https://apps.apple.com/us/app/100cims-mountain-challenges/id6740161401?platform=iphone).
- ⭐ [On GitHub](https://github.com/expofast/100cims).

![app screenshots](https://cdn.sanity.io/images/9r24npb8/production/48621e18159bc6d2b89c6bbe4e5738d6f522da8c-2048x1152.png)

## Expo at the core

The app is built entirely in **React Native**, powered by **Expo.**

On the app:

- [`expo-router` powers navigation](https://expo.dev/router) — bringing file-based routing to React Native with nested layouts, dynamic routes, and modals that just work.
- `nativewind` lets me use Tailwind-style utilities directly in React Native. It makes styling fast, scalable, and developer-friendly.
- A suite of Expo SDKs powers native interactions: `expo-store-review`, `expo-image-picker`, `expo-haptics`, `expo-clipboard`, `expo-device`, and more.

The experience across platforms (iOS and Android) is seamless — and thanks to `expo-dev-client`, development is smooth and blazing fast.

## API architecture with ElysiaJS + Eden

Under the hood, the backend runs a typed, minimal setup using [**Elysia.js**](https://elysiajs.com/), a modern Bun framework that feels like Fastify meets tRPC. It’s built around composability, types, and performance.

- API routes are organized into `public` and `protected` groups
- Auth is handled with a JWT + Bearer strategy, using `@elysiajs/jwt` and `@elysiajs/bearer`
- Database access is powered by [**Drizzle ORM**](https://orm.drizzle.team/), giving me schema-safe queries with type inference on a PostgreSQL DB hosted on Supabase.
- All API routes are mounted via `expo-router`, similar to next.js api routes.

To fetch data on the client, I use **React Query** (`@tanstack/react-query`) together with **Eden**, an Elysia companion from which I get full end-to-end type safety between the API and the app — no manual types or duplication. One repo, fully typed, from database to UI.

![API Architecture with Elysia.js + Eden](https://cdn.sanity.io/images/9r24npb8/production/481131f6b0d901db6cb59739951cd804fa9f84cd-2048x1152.png)

## What’s next?

100cims continues to grow — the new "**Plans"** feature (with internal chat per group) is already helping hikers organize their adventures together. And the next update will bring a fully interactive **map view** for discovering mountains near you.

Future updates will focus on:

- Gamification features (badges, titles, awards).
- Challenge creation by the community.

![app chat](https://cdn.sanity.io/images/9r24npb8/production/65faa00c1897c738ee6671626cb1f0f5cf8807a6-2048x1152.png)

## Try the app

If you love hiking, climbing, or just want to follow the journey:

- 🤖 [On Android](https://play.google.com/store/apps/details?id=app.x100cims.x100cims).
- 🍏 [On iOS](https://apps.apple.com/us/app/100cims-mountain-challenges/id6740161401?platform=iphone).

Explore the solution:

- ⭐ [On GitHub](https://github.com/expofast/100cims).

This app started as a way to fix a personal failure. But now it’s something that others use, love, and build real memories with. If you’ve ever wanted to build something from scratch with Expo — you can.  
  
This summer I'll reach the summit. And I hope some of you will get there with me.