Mobile4 weeks2026

Kostra

Car expense tracker for iOS and Android — fuel, servicing, insurance and trips for every car in the household, with the statistics that show what each one really costs.

Interface languages

Expense categories

iOS + Android

From one codebase

Free

To start — and no advertising

Kostra home screen with two vehicles, their odometer readings and this month’s spending

Kostra expense list grouped by month, with category filters and an all-time total

Kostra statistics screen showing total spent, cost per kilometre and a breakdown by category

Kostra vehicle screen with total spent, cost per kilometre and that car’s expense history

Kostra form for adding a fuel expense, with category, vehicle, amount, currency and a full-tank switch

Project Overview

Kostra records what a car costs its owner. Every expense goes in under a category — fuel, servicing, repairs, insurance, tax, parking, tolls, car wash — against the vehicle it belongs to, and the app turns that history into the figures drivers actually ask for: spend this month, cost per kilometre, fuel consumption over time. One account holds as many vehicles as needed, each with its own odometer and history, and a trip log covers anyone who has to account for their mileage. React Native and Expo on the surface; behind it a NestJS API on PostgreSQL, with request and response shapes shared by both sides so the phone and the server cannot drift apart.

The Challenge

An expense tracker is easy to start and hard to keep up: one skipped fill-up and the statistics stop being true. A record had to take seconds — category, amount, done, with the vehicle already filled in — while still capturing enough underneath (odometer, litres, whether the tank was filled) to work out consumption and cost per kilometre honestly. All of it had to read as native in eight languages, in light and dark, on both platforms, from a single codebase.

The Result

A complete app for iOS and Android, now going through store submission: free to start with one vehicle and three records, and a subscription that opens the statistics, reports, trip log and categories of your own.

What We Built

Every cost in one place — fuel, servicing, repairs, insurance, tax, parking, tolls, car wash

Statistics that answer the real question: spend per month, cost per kilometre, fuel consumption over time

Several vehicles in one account, each with its own odometer and expense history

Trip log with export, for anyone who claims mileage back

Eight languages, multiple currencies, light and dark — the app follows the phone

Timeline

4 weeks

Related Projects

VONZI Start Pack landing page hero section with a 3D render of the starter kit box and a pre-order call to action

View Project

Web

Start Pack Tattoo

Landing page for VONZI Start Pack — a professional starter kit that sells everything a beginner tattoo artist needs in one box.

ReactNext.jsTypeScriptTailwind CSS+1

Cashflow Helper player list showing win rate and game stats

View Project

Mobile

Cashflow 101, 202, 303 Helper

iOS companion app for Robert Kiyosaki's Cashflow board games — real-time financial statement tracking for 101, 202, and 303.

React NativeExpoTypeScriptAsyncStorage

AquaMinder Goals Apple Watch screen for logging water intake with quick-add buttons

View Project

Mobile

AquaMinder Goals

Native Apple Watch app for daily water intake tracking — set goals, log drinks with one tap, and stay hydrated with smart reminders.

SwiftUIWatchKitHealthKitCloudKit

Have a similar project?

Let us talk about your idea. We will help you turn it into a product that delivers real results.

Start a Conversation

View All Work