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YMP

01 /

Product engineer.

I buildproducts.
Yusuf MirzaPıçakcı

The product, the system behind it, and the interface on top.

I take a problem or a half-formed idea and turn it into a working product: the decisions, the architecture, the backend and APIs, the interface, and shipping it. I work across product and engineering rather than on isolated features. Open to projects.

I care about the system behind the interface. One example: ≈ 500 product varieties counted by hand in a Romanian PVC factory — that became a stock ledger, an API and two apps. Senzovia is a prototype I built alone.

02 — Work

What I’ve built,and what it covers.

3 products, each a different kind of engineering: an AI platform built around a strict schema, a 3D try-on wired into an e-commerce platform, and operational software across desktop, mobile and an API. Point at a name to see the interface; open it for what I built, what the product needed and what the demo does and doesn’t cover.

03 — What I do

From the problemto a working system.

How I work

I work across the whole product: what it should do, how it is structured, the data and API behind it, the integrations it depends on, the interface in front, and getting it running. I can start from a requirement you already have, or help shape the product before anything is built. I care most about the part users never see, the system the interface sits on, and I make the pragmatic technical call and say why.

01

Product thinking and architecture

Before code: what the product has to do, who it is for, what the architecture has to carry and what can wait. I would rather settle that in a few conversations than discover it in the codebase. I can start from a requirement you already have, or help shape one.

  • Turning an unclear idea into a buildable first version
  • Architecture and boundary decisions
  • Data model and domain rules
  • A written plan a team could build from

02

Backend, APIs and data

The part behind the interface: the data model, the API, authentication, tenancy. Senzovia is the clearest case: stock modelled as a ledger of movements, one Cloudflare Worker API, and a shared core under a desktop client and a mobile client.

  • APIs and data models
  • Authentication, MFA and tenant isolation
  • Validation at the boundaries
  • PostgreSQL, MongoDB and Cloudflare D1

03

Interfaces that match the system

The interface is built against the real system, not a mockup of it, and it is designed for the person using it: a 3D fitting cabin on a shop’s product page, a visual builder for generated sites, a stock screen for a factory.

  • Web, desktop and mobile clients
  • 3D experiences where the product needs one
  • Bilingual interfaces (Turkish and English)
  • Responsive and accessible by default

04

Integrations and shipping

Products live inside other systems. Karyamoni connects to the IKAS store platform with an OAuth flow, signature-verified webhooks and product sync; Yappaflow carries connectors toward four CMS platforms. I deploy what I build.

  • OAuth and token refresh
  • Webhooks and product sync
  • CMS and third-party APIs
  • Deployment on Vercel and Cloudflare

05

AI where it actually helps

A model is one component with a cost and a failure mode, so the decision is where it belongs. Yappaflow constrains generation to a schema so the output can be edited and validated. Senzovia keeps stock rules deterministic and treats computer vision as one more input.

  • Structured generation against a schema
  • Deterministic rules around uncertain output
  • Human review for uncertain cases
  • Knowing when a feature doesn’t need AI

01 — The brief

A factory
counts by hand.

Roughly 500 product varieties, typed into Excel.

A worked example · Senzovia, a prototype I built alone

02 — Understand the product

So I started
with the work.

Before any code I wrote down how the work actually happens: who counts, who ships, what ends up in Excel, and what has to stay true. The product is that workflow, made reliable.

  1. 01Products and SKUs
  2. 02Stock and movements
  3. 03Counting sessions
  4. 04Customers and shipments
  5. 05Excel import and export
  6. 06Desktop and mobile clients

03 — Decide

One ledger owns
the truth.

Three decisions in the data model · the clients hold no stock state of their own

Every stock change is a movement, written with the quantity in one atomic batchLedger
A count refuses to close if stock moved after an item was countedChecked
A retried request replays its stored response instead of booking twiceIdempotent

04 — The rule

Stock never
goes negative.

The rule lives in the system, not in the screens. The screens can stay simple because the thing underneath them is strict.

05 — The boundary

One path for every input.

Every stock change takes this path

InputValidateLedgerAuditClients

Planned: camera counting arrives as one more input

06 — What exists

The workflow, before and after the prototype

Typed into ExcelA ledger

It is a prototype, and the screenshots on this site use invented sample data, so I make no claim about outcomes. What it does show is the work: a model with rules, two clients, and Excel import and export so the old way can be carried across.

07 — How I work

Product
first.

I start from what the product has to do and who it is for, then make the engineering decisions that serve it: the model, the boundaries, what can wait. The code follows from those.

Senzovia is one product. Karyamoni and Yappaflow are others, with different problems and different engineering. If you have a product to build, or one that needs an owner, this is how I would work on yours.

05 — How I work

Not a methodology.
Just the order.
  1. 01

    Understand

    I start with the problem, not the feature list: who it is for, what they do today, what that costs them, and what would count as working. If I can’t say it plainly, there is nothing to build yet.

  2. 02

    Decide

    I settle the smallest version that tests the idea, and the decisions it has to survive: the data model, the boundaries between parts, what must be real now, what can be faked, and what can wait.

  3. 03

    Build

    I build the layers together — data, API, integrations, interface — so they agree with each other. I use AI coding tools for speed; the architecture, the decisions and the review stay mine.

  4. 04

    Shape the interface

    I put real screens in front of you early, because a working interface settles arguments a document can’t. The people using the product feel the interface, so it gets the same care as the system underneath it.

  5. 05

    Ship and iterate

    I ship something real, then change it based on what the product turns out to need. I check it against what we said would count as working, and where I can’t show that, I say so.

I make the call, say why, and change it when the product shows me I was wrong. Pragmatic beats clever: the right decision is the one the product can live with.

06 — Proof

Don’t takemy word for it.

What the work is made of, taken from the three products and checked against their repositories and demos. These are facts about what I built, not usage figures: none of it is a user count, a revenue number or a production claim, and each line says where it comes from.

Senzovia · the problem

≈ 500

Product varieties a Romanian PVC factory counts by hand and types into Excel. The data model and the Excel import are built around that workflow.

From the project brief · starting point, not a result

Senzovia · the system

2 clients, 1 API

A desktop app and a mobile app over one Cloudflare Workers API, with the domain rules and validation in a shared core package both clients and the API import.

Repository structure · private, walkthrough on request

Senzovia · a decision

24 h

A retried request replays its stored response instead of booking a second stock movement, and a stock change and its ledger row are written in one atomic batch.

Written in the repository’s Stage 1 decisions · prototype

Karyamoni · the integration

OAuth + HMAC

The IKAS app uses an authorization-code flow with token refresh, and verifies incoming webhooks by signature before acting on them.

Implemented in the repository, with a test for the signature check · not run against a live store here

Karyamoni · the experience

TR / EN

A 3D garment viewer on a mock product page, a guided walkthrough and a playground, in Turkish and English.

Public demo · illustrative fit values

Yappaflow · the design

1 schema

The AI fills one canonical JSON project instead of writing free-form pages, so the visual builder and the CMS exports work from the same structure.

How the system is designed · the showcase doesn’t demonstrate every generation path

Written down

  • Senzovia: why the ledger is the source of truth

    Stock as movements, tenancy enforced in the database, and what a computer-vision result has to pass before it can touch stock. In the repository’s architecture and decision documents.

  • Karyamoni: what the first version leaves out

    An IKAS-first scope, tops before the rest of the wardrobe, and the assumptions that still have to be confirmed. In the product plan, MVP spec and technical architecture.

The repositories are private, so these stay in the documents until I can walk you through them. Ask, and I will: it is the quickest way to see how I make a decision.

07 — Exploring

What I don’thave an answer to yet.

Where my attention goes between projects, and the questions I would bring to yours. It changes; that’s the point of writing it down.

  • 01 — Open

    Counting without a person in the loop

    Senzovia’s stock ledger works. The harder product is the one where a camera does the counting and a person is called only when the system is unsure. So far that exists only as an isolated experiment, and the open question is what the ledger has to refuse before a vision result is allowed to touch stock.

  • 02 — Open

    How much structure an AI feature needs

    Yappaflow works because the AI fills a strict schema instead of writing free-form pages. I want to find where that stops being enough: which parts of a product want a schema, which want judgement, and who decides.

  • 03 — Open

    A fit recommendation you can believe

    Karyamoni’s demo uses illustrative fit values. A real size recommendation needs real garment measurements and an honest account of how sure it is, and I don’t yet know how much of that a merchant will realistically provide.

  • 04 — Open

    One product, several surfaces

    A desktop client, a mobile client and an API sharing one core is a good deal until a screen needs to behave differently on each. I keep coming back to where the shared layer should stop.

  • 05 — Open

    Knowing what a product is doing

    I’m working out how little instrumentation is enough to make a product honest about itself — what is used, what is slow, what fails — without turning every feature into a monitoring project.

Last revised — October 2026

These are open questions, not expertise. Nothing here is finished — when one of them produces something I can show, it moves up the page and becomes evidence.

08 — Who is Yusuf

I take products fromidea to running system.

I’m a product engineer. I work on what a product should do, how it should be structured, and then I build it: the backend and data, the APIs and integrations, the interface, and getting it running. I use AI where it earns its place in the product, not because it is expected.

I work alone, so one person owns the whole thing: the decision, the code and the consequences. That suits a founder getting a product off the ground, a team that needs an internal tool built properly, or a company with software that needs someone to take responsibility for it. I can start from a requirement you already have, or help shape the product first.

I use AI-assisted development as a tool, the way I use a type checker or a debugger. It speeds the work up; the architecture, the decisions and the review stay mine. And I keep the product honest by checking it against reality: what it does, what it costs, and where my first idea was wrong.

  • Product thinking and architecture
  • Backend, APIs and integrations
  • Interfaces people actually use
  • Open to projects

09 — Work with me

Have somethingyou needbuilt?

A new product, an internal tool, or the system behind an interface that already exists. If the problem isn’t pinned down yet, I can help shape the product and the architecture before anything is written. Tell me what it is, who it is for and when you need it. I answer with what I would build, in what order, and what I would decide first — and I say so when what I learn along the way contradicts the plan, including mine.