Karol Grülling

iOS coder / developer

Swift, iPhone, iPad, Apple Watch
- Code Lines Every Day -

My Projects

My Books

Released 09/19

My Books is one of the most used book apps in the App Store. This public domain ebook reader and audiobook player is simply the easiest way how you can read or listen to thousands of classics that were proven over time. Download your favourite book and have it available at any time even if you are offline. Change the appearance of the reader so the book is perfectly readable even in the dark. Listen to your audiobooks while the app is in the background so you can use your phone freely without interrupting the playback.

EPUBKit, Lottie, JavaScript, WebKit, AVFoundation/MediaPlayer, Firebase, Realm, REST API, StoreKit - Consumable purchases/Subscriptions, Push notifications.

Facts App

Released 06/19

Open the app and find out something you didn't know about your location. Or just browse through dozens of facts from all around the world and become smarter every day.

REST API, CoreLocation, AirTable, Lottie, Push notifications


Released 01/19

Dohliadac is a sale price search engine which allows visitors to browse through product discounts in 18 retail chains that operate in Slovakia. With this app they can browse and search between them, see all the current discount catalogues or add products into shopping list that shows how much money was saved. Products can be set as watched so the app is able to inform every time they go on sale. Map feature shows locations of all the stores with ability to navigate to them or get a taxi by deeplinking into Uber app.

REST API, OAUTH 2.0. Push notifications, CoreLocation, Lottie, Facebook SDK

Milch Concept

Released 07/18

Milch Concept is an industrial app for renters of milk dispensing machines which offers detailed information about the current state of every milk dispenser and delivers notification every time a particular machine is out of service, or running out of milk. Simple, but handy application providing a lot of value for customers of this service.

REST API, Push notifications


Roofus is a digital service book app offering its users a way to keep track of every reconstruction and repair that occurred to the property they own. On top of that, Roofus is also a marketplace for home renovation, connecting skilled craftsmen with property owners. Register your property, configure its inventory and keep track of all the events that occurred to it. Upload floor plans, electricity plans or any kind of documentation so you make it digital and available at any time to you in your phone. Share this documentation with craftsmen, to make sure they know exactly every detail needed about your property required to get their job done properly.

REST API, CloudKit, Firebase, CoreLocation, Push Notifications, FacebookSDK, Google+ SDK


Released 12/2017

Companion app for Kuberg's electric motorbikes. Pair your iPhone with your bike's Wi-Fi network and use the app as a way to setup bike's behaviour. Set bike's top speed and maximum torque or use it as a speedometer. Control the riding perimeter and limit how far can your child ride. Monitor your riding stats and update bike's firmware.
App transmits custom packets adhering to communication protocol provided by bike's manufacturer. The whole data communication is encapsulated into standalone iOS framework allowing it to be integrated in any other app.

Custom data packet generation, SystemConfiguration

Salt or Sweet

Released 01/17

Have your say and rate the movie you've recently watched. Browse through user reviews in amazing "Tinder-like" user interface and find a movie to watch today! Move recommendation app at its best.

REST API, OMDB, Firebase database


Released 11/2017

KINGL is a digital postcard creator. Create a beautiful postcard with your message in it and share it with your loved ones. Choose one of the thousands of designs in the gallery and hundreds of fonts to make your message stand out. Or create your own postcard from the photo you've taken.

CoreImage, CoreData, ContactsUI, StoreKit - In App Purchases, Facebook SDK, REST API


Released 05/16

App developed for Slovak band Kontrafakt serves as its social media hub displaying content from multiple social media accounts. Allows its fans to ask questions directly or purchase merchandise from the online store. Music player offers whole discography and handy controls situated in menu allow to browse through app and control the music at the same time.

REST API, AVFoundation/MediaPlayer, Facebook SDK, Instagram SDK


Footshop is one of the biggest online sneaker stores in central Europe. This notification driven app informs its users about upcomming releases and allows them to shop directly from it.

Push notifications, REST API, Facebook SDK.


Content consumer app for the biggest lifestyle magazine in Slovakia. Allows you to browse, search and read all the articles, comment on them, or store them as favorite so they are available also while you are offline. By following particular hashtags or categories you will get a tailored feed of articles just for you. Every time a new article is published you receive a push notification.

REST API, Facebook SDK, Push notifications.

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Simply raw

Released 02/15

With Simply Raw you can prepare your all week food diary within five minutes. Browse through hundreds of carefully chosen raw recipes or let the app pick the ones you can prepare at home by entering ingredients you have available at the moment.

Do you miss something? Create a shopping list which you can carry with you all the time! Simply Raw is simply the best choice for everyone who wants to change the diet.

Parse database and framework integration


Released 11/14

Application developed for PAY. clothing brand. Users are able to take photos or choose some from their library and upgrade them with filters and with the PAY. logo.

Logos can be placed, rotated, enlarged and reduced by pinching s well as highlighted or dimmed by swiping from left to right. Photos can be shared on Instagram, Twitter or on Facebook.

GPUImage OpenGL image processing.


Released 11/14

App for a music and lifestyle web portal - www.90bpm.sk offers direct access to site's news and all of its content from social networks with full social capabilities such as liking, sharing, favoriting or retweeting.

Articles can be stored into Core Data database so they are accessible even offline.

SOAP, Facebook SDK, Twitter SDK, CoreData

Biela noc 2014

Released 10/14

An official guide for the most visited contemporary art festival in Slovakia - Biela Noc (White Night). Provides summary information about the festival together with list of artists, dictionary of artistic terms and map which serves as festival navigation guide.

Fireworks feature allowed thousands of users to fire more than 80 000 "rocket messages" in form of a digital fireworks that was projected on the huge canvas situated in the city centre. Multimedia feature offers video content from the festival's Vimeo channel.

Facebook POP, REST API, Vimeo API


Released 10/14

iEcka provides quick access to detailed information about the most common food additives. Works with locally stored database of E-Numbers with ability to search between them.

Košice - Západ

Released 09/14

An official municipal app for citizens of a city district in Slovakia, offering the latest district's news.

Users are able to create photo reports which can be sent directly to district's mayor. Map feature shows locations of district's hospitals, police stations, drug stores and mayors office.

REST API, CoreLocation, MapKit


Released 06/14

Fitmee allows its users to track daily fitness training performance. Users can capture todays workout and compare them with workouts from past. Fitmee is a multilingual app support English and Slovak language.


Asistentka BEKO

Released 03/14

iPad application used by sales representatives of BEKO for planning and reporting business visits. After authentication with QR code users can access their daily plans and execute them directly in the app. Representatives keep track of their visits and numbers of products currently in stock for a particular vendor. For each day application generates report which is sent to the backend for further reporting. In case when there is no internet connection available, reports are stored and synchronized when the device comes online.

REST API, ZXing OR reader library, CoreData.

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Released 12/13

Your personal speeding fines calculator. iPokuta is able to show you the highest possible speeding fine you can be charged by determining your current speed by GPS.



Released 06/13

Project developed for client Umakov - product * system * design, transforming iPhone into barcode scanner.

Scan barcode in catalogue and get the price for desired product. Offers ability to switch between 6 languages.

REST API, ZXing QR reader library.


Released 02/13

Dancing and talking puppet which conjures smile on every human face that sees and hears it. iGaspar, accompanied with his trumpeter is able to tell his favourite jokes anywhere and anytime.

Became temporarily no.1 in Entertainment category in Slovak App Store.


Released 01/13

Next level sound effect app providing everything that a real comedian needs. Its clear idea made it popular even though there are many similar applications in the App Store. Achieved over 40 000 downloads in more than 15 different countries.

AudioToolbox, local SQLite database

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