Umut Keltek · builder of systems

I build systemsto understand systems.

Software, markets, my own mind. The instruments that survive become apps you can use. The infrastructure underneath runs the whole studio.

a map of the systems in my head
The system behind the studio

One person doesn’t ship a portfolio by working harder. I built a system to run the studio.

keltek runs on an operating system I built for it: agents I direct, a memory that compounds what every project teaches, and pipelines from exploration to the App Store. The apps are what the system produces. The system is the real work.

Agents I direct

A multi-agent harness that does the work I would otherwise do by hand, held to my standards.

A memory that compounds

Every project becomes reusable knowledge, so the next one starts ahead instead of from zero.

Idea to App Store

Pipelines that carry a question I am stuck on all the way to a shipped, finished product.

Most studios are a team. This one is a system.

Method · how the work happens

I build the system first. The product comes later.

Almost everything here started as a tool I wanted for myself, a way to make sense of something I was stuck on. An emulator that only plays the cartridges I own. A paycheck calculator that actually accounts for night shifts. A way to keep three years of messy notes from turning into noise.

I build the system to understand the problem; the ones that turn out useful to other people become apps. I’m wary of organizational theater and of being valued only for being useful, which is why I work alone, and why each of these is a small, finished object rather than a pitch deck.

Build to understand. Ship what turns out useful. Stay small on purpose.

the working principle

What the system ships

Products that fell out of system exploration.

Each began as an instrument I built to understand a system. These are the parts you can download; the systems behind them run the studio.

  1. 01

    HealthSave

    Export & visualise your Apple Health data. On-device, no account.Health · Shipped

  2. 02

    ShiftWorth

    Paycheck & shift-pay calculator for nurses and shift workers.Finance · Shipped

  3. 03

    Hearing Helper

    Turns your iPhone into a mic that lifts nearby speech.Health · Shipped

  4. 04

    Clarity

    On-device photo cleaner: duplicates, screenshots, big videos.Utilities · In progress

  5. 05

    RetroVault

    A GBA emulator that only plays files you own.Games · In progress

  6. 06

    Drambook

    A private cellar book for whiskey collectors.Lifestyle · Shipped

  7. 07

    CatchTime

    Honest fishing tides & solunar. Light first, moon second.Outdoors · Shipped

  8. 08

    1099 Tax & Mileage

    Dead-mile tracking for gig drivers, built for an audit.Finance · Shipped

  9. 09

    Darts Scorekeeper

    Cricket & 501 scoring with checkout help.Games · Shipped

  10. 10

    Honest Decibel

    A sound-level meter that refuses to overclaim.Utilities · Shipped

  11. 11

    Honest Tan

    A UV-index sun timer that tells you when to stop.Health · Shipped

  12. 12

    PostReady

    Record portrait and landscape at the same time.Photo & Video · Shipped

  13. 13

    Quiet Couples

    A private love tracker for long-distance couples.Lifestyle · In progress

  14. 14

    Color Formula

    Formula & bowl-cost tool for hair colorists.Productivity · In progress

  15. 15

    ReconstIQ

    Peptide reconstitution math that shows its work.Health · In progress

  16. 16

    ClaimGuard

    Find class-action settlements you can actually claim.Finance · In progress

  17. 17

    InkCare

    Tattoo aftercare, guided day by day.Health · Shipped

Labs

The systems, experiments, and research underneath.

Open-source infrastructure, products that live outside the App Store, and the research behind them. Rougher than the shipped apps, and more honest about how the work actually gets made.

  1. 01

    Switchback

    A single-binary Rust gateway that routes LLM traffic across providers and accounts, with fallback, budgets, encrypted credentials, and explainable metadata-only tracing.Open source

  2. 02

    HealthSave Observatory

    A self-hosted health-data substrate that unifies Apple Health, Whoop, and Garmin into one private, local record. The engine behind the HealthSave app.Open source

  3. 03

    PazarMap

    Turkey's street-market finder: 2,777 markets across 63 cities, built on the official registry, searchable by city, district, and day.Live product

  4. 04

    72saat

    A safety-bounded offline earthquake copilot: LLM guidance kept inside verified safety limits, designed to work when the network is down.Research

  5. 05

    SkillAce

    AI talent assessment: role-play simulations that score the soft skills a CV cannot show, like empathy and persuasion, for hiring and development.Live product

  6. 06

    LLMs for Game Narrative Design

    Master's thesis (Bahçeşehir University, 2024): fine-tuning LLMs on structured Assassin's Creed Odyssey quest data to generate game quests. The finding worth keeping is that base models often beat the fine-tuned ones, which says a lot about when fine-tuning actually earns its cost.Master's thesis