Diego Ferreira

Diego Ferreira · Mobile developer in Ireland

Native apps for iPhone and Android.

I design, build and ship my own apps end to end, in Swift and Kotlin. Fast, focused and private by default: no account to sign up for, and your data stays on your device wherever it can.

See the appsEmail me
  • Budget Calendar
  • Take Home Pay
  • LED Banner
  • Koin
  • Calcly
  • Unseen
Apps
6
Live on Google Play
4
Coming to the App Store
2

iOS, iPadOS and macOS

Swift · SwiftUI

Budget Calendar

Budget Calendar & Cash Flow

See every day's balance before it happens.

  • A day-by-day balance forecast, 3 to 12 months ahead
  • "Can I afford it?" simulator with safer dates and installments
  • Bills, cards and debts in one plan, imported from bank statements
  • No ads, no account: your budget stays on your device
  • Swift
  • SwiftUI
  • SwiftData
  • Swift Charts

Coming soon to the App Store

More about Budget Calendar
  • Calendar view: every coming day coloured by your safety buffer
  • Home screen: how much is safe to spend until payday
  • Can I afford it? Your forecast with and without a purchase, side by side
  • Plan: bills, installments and debts in one place
  • Budget Calendar in dark mode

Take Home Pay

Take Home Pay Ireland

Your Irish salary after tax, in seconds.

  • Income tax, USC and PRSI broken down band by band
  • This year and the next Budget compared, in your monthly pay
  • Work backwards from the take-home pay you want
  • No ads, no tracking, on iPhone, iPad and Mac
  • Swift
  • SwiftUI
  • Swift Packages
  • macOS

Coming soon to the App Store

More about Take Home Pay
  • Your take-home pay with income tax, USC and PRSI worked out
  • Your full PAYE breakdown: bands, credits, USC, PRSI and pension
  • Budget 2027 compared with 2026 in your monthly pay
  • Target pay: find the salary for the take-home pay you want
  • Take Home Pay in dark mode

Android

Kotlin · Android SDK

LED Banner

LED Banner - LED Scroller Text

Turn your phone into a scrolling LED sign.

  • Scrolling text in any direction and speed, with real LED dots
  • Neon glow, rainbow, gradients and 8 display fonts
  • Templates for concerts, airports, birthdays and more
  • GIF and video export, no ads, no account
  • Kotlin
  • Room
  • Coroutines
  • Video encoding
Get LED Banner on Google PlayMore about LED Banner
  • Editor: type a message and style it as an LED sign
  • Bright scrolling text shown full screen
  • Neon glow and rainbow text effects
  • Templates for concerts, airports, birthdays and more
  • Export your banner as a GIF or video

Koin

Koin: Currency Converter Rates

Every currency you need, at once.

  • 140+ currencies, converted all at once
  • Rate charts for 7 days up to a year
  • A calculator built into the amount field
  • Works offline, with a home-screen widget
  • Kotlin
  • Room
  • WorkManager
  • App widgets
Get Koin on Google PlayMore about Koin
  • All your currencies converted at once
  • Rate history charts for 7 days, 30 days, 90 days and 1 year
  • Calculate as you convert: add, subtract, multiply and divide in the amount
  • 140+ currencies in your own order
  • Your own rate or fee, in the light theme

Calcly

Calcly: Calculator & Converter

A calculator that gets the maths right.

  • Exact decimal maths and correct order of operations
  • A full scientific keypad: rotate to landscape
  • Unit converter with 14 categories and 100+ units
  • History you can review, restore and copy
  • Kotlin
  • Room
  • Coroutines
  • Big-decimal maths
Get Calcly on Google PlayMore about Calcly
  • Fast, clean calculator with correct order of operations
  • Scientific mode: trigonometry, logarithms, powers and memory
  • Unit converter with 14 categories and 100+ units
  • History: review, restore and copy past calculations
  • Calcly in the light theme

Unseen

Unseen - No Last Seen

Read your messages without being seen.

  • Read messages even after the sender deletes them
  • Read new messages without showing them as read
  • Choose which messaging apps to save
  • Received images, videos and audio in one place
  • Message text never leaves your phone
  • Kotlin
  • Room
  • Notification listener
  • Play Billing
Get Unseen on Google PlayMore about Unseen
  • Read a message even after the sender deleted it
  • The Unseen inbox: every message you received, saved
  • Your privacy above all: read new messages without the read mark
  • Messages saved from your favourite messaging apps
  • The images, videos and audio you received
  • Settings: choose which apps to save notifications from

About

I'm Diego, an independent mobile developer based in Ireland. I take each app from idea to store: product and design, native code, tests, localisation, store listings and releases.

My apps do one job well. They work offline wherever they can, keep personal data on the device, and are translated into up to 15 languages. Everything ships under DF Dev Apps.

What I work with

  • Swift
  • SwiftUI
  • SwiftData
  • Kotlin
  • Android SDK
  • Room
  • Coroutines
  • Firebase
  • fastlane
  • TypeScript

Questions, feedback or an idea?

Write to me. I read every message.