fen0m
fen0m avatar: bronze Perseus statue with a glowing blue eye

Independent developer · Slovakia

fen0m

I design and ship consumer apps end-to-end: the website, the native iOS and Android apps, the data pipelines behind them, and the store releases. Currently building SeaTempMap and Calc².

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About

Who is behind fen0m

fen0m is the label under which I publish my apps and websites. I work alone and take each product from the first sketch to the store listing: product design, front end, native mobile ports, the back-end data pipelines, localisation, search optimisation and the release process on the App Store and Google Play.

My main project is SeaTempMap, a live sea-surface-temperature map that turns satellite and ocean-model data into a number a traveller can read in a second. It runs as a website with 175+ curated destination pages in 15 languages, plus native iOS and Android apps with home-screen widgets, a free embeddable widget and a WordPress plugin.

The second one is Calc², a calculator built around one idea: large square keys with no gaps, so a calculation that matters never fails on a missed tap. It ships on iPhone, iPad, Apple Watch and Android with a shared, bit-exact calculation engine.

Two more are close behind. Bell Hours answers in one glance whether the US markets are trading, counts down to the next bell and keeps verified holiday calendars through 2028, with iOS and Apple Watch apps in development. Phone Drops tracks flagship phone launches: a calendar of confirmed release dates and a cycle tracker showing which phones are fresh and which are about to be replaced.

4products on the web, two of them also as native apps
175+SeaTempMap destination pages
30languages in Calc², 15 in SeaTempMap
1 kmsatellite sea-temperature resolution

Projects

Websites and apps I have built and run

SeaTempMap: world map coloured by live sea surface temperature, from cold blue polar seas to warm red tropical coasts

SeaTempMap

Live sea temperature map · web, iOS, Android

Today's sea temperature at any coast on Earth, a 10-day sea forecast, UV index, live weather and long-term monthly averages, free and in 15 languages.

  • Satellite-based 1 km sea-surface-temperature analysis (NASA MUR), updated daily with an intraday adjustment
  • Forecasts blended from Copernicus Marine models; air temperature and UV from Apple WeatherKit
  • 175+ curated beach destinations, country and sea hubs, tap-anywhere probe on the interactive map
  • Native apps with widgets, plus a free embeddable card and a WordPress plugin for other sites
  • Next.js
  • TypeScript
  • MapLibre GL
  • SwiftUI
  • Jetpack Compose
  • Python
  • Vercel
seatempmap.com → Download on the App Store Get it on Google Play
Calc² on an iPhone: a dark calculator with large square keys joined edge to edge and orange operator keys

Calc²

Square-key calculator · iPhone, iPad, Apple Watch, Android

A calculator that fixes the one thing that ruins a result: the missed tap. Big square keys with no gaps between them, on a dark body with orange operators.

  • Expression engine with parentheses and operator precedence, the expression shown above the result
  • Scientific mode in landscape: trigonometry, logarithms, powers, roots, memory, Rad/Deg
  • Unit conversion and live currency rates from the European Central Bank
  • 30 languages including right-to-left, one shared engine on Swift and Kotlin, verified bit-exact
  • Paid once, no ads, no subscriptions, no in-app purchases
  • Swift
  • SwiftUI
  • watchOS
  • Kotlin
  • Jetpack Compose
calcsquared.com → Download on the App Store Get it on Google Play
Bell Hours: a dark dashboard answering "Is the stock market open today?" with a red CLOSED status, a countdown to the next opening bell and every session converted to the visitor's own time zone

Bell Hours

Is the stock market open? · web, iOS and Apple Watch apps in development

A one-glance answer to whether the US markets are trading right now, with a live countdown to the next bell and every session shown in the visitor's own time zone.

  • Live status for five markets: stocks, options, futures, forex and bonds
  • Holiday and early-close calendars for 2026 to 2028, taken from NYSE and SIFMA and re-checked every day by an automated watcher
  • A page for every US market holiday, per-year calendars and a tomorrow view
  • Free embeddable widget for other sites, plus a press page serving the whole calendar as JSON
  • HTML
  • JavaScript
  • Python
  • SwiftUI
  • watchOS
  • Vercel
bellhours.com →
Phone release calendar: a month grid of upcoming flagship launches, each entry tagged with the region where that phone goes on sale

Phone Drops

Phone release calendar and cycle tracker · relaunching as phone-drops.com

Every confirmed flagship launch on one calendar, and a cycle tracker that tells you whether the phone you are about to buy has just landed or is about to be replaced.

  • Release calendar of confirmed dates only, no rumours, split by China, global and EU availability
  • Release cycle bars: how far each flagship is through its generation, with the successor's month projected from that line's own cadence
  • Full specifications for every phone covered, and a side-by-side comparison of any two
  • Launch-day news at European prices, in 16 languages
  • Next.js
  • React
  • TypeScript
  • Tailwind CSS
  • Vercel
live today as peakphones.com →

How I build

The stack behind the projects

Web

Next.js and React in TypeScript, deployed on Vercel. Static-first pages, edge caching, structured data and localisation designed in from the start, not bolted on.

iOS

Swift and SwiftUI, with WidgetKit home-screen widgets and a watchOS companion where it makes sense. Native controls, native feel, no cross-platform wrapper.

Android

Kotlin and Jetpack Compose with Glance widgets, mirroring the iOS app one-to-one so both platforms ship the same feature on the same day.

Maps and data

MapLibre GL for the interactive map; Python pipelines that bake NASA MUR satellite sea temperature, Copernicus Marine forecasts and ERA5 climatology into fast static tiles.

Localisation

Every product ships multilingual: 15 locales on SeaTempMap, 30 on Calc² including Arabic and Hebrew, with native names, declension and store listings per market.

Release and growth

App Store and Google Play publishing, review notes, screenshots, in-app purchases where needed, plus technical SEO, sitemaps, schema.org and an llms.txt for AI search.

Contact

Partnerships, press, data questions

The quickest way to reach me is email. I am happy to talk about SeaTempMap data partnerships, embedding the sea-temperature widget on travel or hotel websites, press requests, or app collaborations. I reply in English or Slovak.