Mon Garage

Buy, repair, sell on: the books of a car enthusiast.

  • Android

2026

My father-in-law is a car enthusiast. He never stops talking about his old red 205 GTI, the one on the icon. He buys Peugeots, repairs them and sells them on, and his whole activity lived in a phone note he could no longer make sense of: what he had paid, what he had replaced, what he hoped to get back.

In September 2026 I made him an app to organise it: his cars and their status, from spotted to sold; what was done on each and what it cost; his tasks and his next appointments; and a dashboard that takes stock of the whole activity. It runs on his Android phone, with no server and no account: everything stays with him, with a backup and, if he wishes, his own Google Drive.

He uses it every day: the captures on this page come from his phone, with his 206 CC under repair.

The card of a 2007 Peugeot 206 CC Roland Garros, with its photo: bought for €500, €770 in expenses, €1,270 invested, and a resale target of €3,500.
The same car’s history, month by month: a soft top repaired, a starter motor bought then fitted by hand, a car radio.
The car’s spec sheet: Peugeot 206 CC Roland Garros, 2007, 215,000 km, petrol, manual gearbox, Grand Chelem green, bought on 1 April 2026.
The list of cars, with their status (in repair, for sale), the amount invested and the resale target.
A car being repaired: purchase, expenses, invested, target, and the task list.
A car’s history: finished tasks, work done and expenses, month by month.
The summary: capital tied up, total profit, margin, average duration, hourly earnings and best deals.

What was done

  1. 01

    The app

    An Android app for a single user, designed and built alone, from the screen to the database: the garage, each car’s page, its tasks, its history, its appointments, the summary and the settings, light or dark.

    Expo · React Native · TypeScript

  2. 02

    The local database

    All the data on the phone, in a SQLite database: cars, tasks, history entries, appointments and photos, amounts kept to the cent. The app works offline.

    SQLite

  3. 03

    The computations

    Each car’s and the garage’s accounts, invested, profit, margin, days tied up, hourly pay, best and worst deal, written as pure functions and recomputed at every change.

    TypeScript

  4. 04

    The reminders

    One reminder per appointment, from a quarter of an hour to a week before, scheduled as a local notification and recomputed at every launch, after every change and after every sync.

    Local notifications

  5. 05

    The backup

    A complete backup in one file, photos included, exported through the share sheet and imported back by merging: the latest version of each item wins, nothing is deleted.

    JSON

  6. 06

    The sync

    An optional sync through the user’s own Google Drive, in a private folder only the app reads: data merged, deletions propagated, photos as separate files.

    Google Drive

Isometric drawing of a Peugeot 205 GTI, the one on the icon, and a phone lying beside it. The phone’s screen changes with each step: a car’s page with its photo, a list of tasks to tick, a dated history, an agenda with its reminder bell, a car’s accounts as bars, the list of cars, the summary as bars, then a small database on the phone, and a crossed-out cloud. At the history step, the car is taken apart as during a repair: body lifted, engine visible, wheels pulled out.

How it works

  1. Scroll: the drawing follows.

  2. 01 / 08

    Register a car

    The make is enough to start; the model, the year, a nickname, the mileage or the plate come when you have them. Its status follows its path: spotted, bought, under repair, for sale, sold. Its photos, taken on the spot or picked from the gallery, come next, the first one as its cover.

  3. 02 / 08

    List what is left to do

    Call the mechanic about the gearbox, order a spare part: each task has its name and an estimated cost, and moves in one tap from “to do” to “in progress” to “done”. The car’s page adds up the estimates of what is left to do.

  4. 03 / 08

    Trace what has been done

    A part bought, a job done yourself, a visit to the garage, paperwork or a simple note: each entry is dated, with its amount, its supplier and the hours spent. The history reads month by month, with each month’s total, and a finished task writes itself in.

  5. 04 / 08

    Never miss an appointment

    A buyer’s visit, the garage, the roadworthiness test: each appointment has its time, its place and its contact, and a reminder, from a quarter of an hour to a week before. The agenda gathers those of every car, overdue ones first, and a button calls the contact.

  6. 05 / 08

    Keep a car’s accounts

    Its page shows the purchase, the expenses and the total invested, then the target price and the profit aimed at. When the time comes to sell, the profit and the margin are computed before you confirm, and the spec sheet gives how long the car tied up money, from purchase to sale.

  7. 06 / 08

    See every car at a glance

    The garage lists them with their status, what they have cost, and their target or their profit. You filter by status, search by name, plate or serial number, and sort by date, name, amount invested or profit. Sold cars leave the list without disappearing.

  8. 07 / 08

    Take stock of the whole activity

    The summary does the books for the whole activity: the capital tied up in the cars in progress, the total profit and this year’s, the average profit and duration of a deal, what an hour of work brings in, and the best and the worst deal.

  9. 08 / 08

    Keep hold of your data

    Everything stays on the phone: the app works in the garage, with no network. A complete backup, photos included, exports to one file and imports back without overwriting anything. If you wish, the data syncs through your own Google Drive.

Specifications

Collection
Personal products
Date
2026
Context
A personal project, for my father-in-law, a Peugeot 205 GTI enthusiast: that’s the car on the app’s icon.
Role
Design and development
Built with
Expo · SQLite
Platforms
Android