One developer · Buenos Aires · works with US and European hours
Not an agency, not four months, not a team you have to manage. One person builds your app for iPhone and Android, sets up everything behind it, and handles every rule Apple and Google throw at you. Fixed price agreed before we start. You own all of it at the end.
from $4,500 · usually 3 to 6 weeks · iPhone and Android · both stores handled
You keep the app, the accounts and everything I write. No monthly retainer.
Start where you actually are
You know what you want and roughly who it is for. Maybe a sketch, maybe a competitor you like. No designer, no code, no accounts.
From $6,000 · 4 to 6 weeksFirst step: a call to size it honestly Started and stuckYou tried an AI tool or a no-code builder, or a developer who stopped replying. It works on your screen and nowhere else.
From $4,500 · 3 to 4 weeksFirst step: I tell you what is salvageable Already liveIt is in the stores and something is wrong. Crashes, bad reviews, an update you cannot ship, a deadline from Apple or Google.
From $90 an hourFirst step: find out what is actually brokenThe part nobody warns you about
Most projects do not fail because the screens were hard to make. They fail in the gap between "it works when I show it to you" and "a stranger downloaded it and it works for them too". Here is what actually lives in that gap.
Old devices, bad signal, a battery at four percent, a person who taps the wrong thing twice. The version people download behaves differently from the version on the developer's screen, and the difference only shows up once real people are holding it.
You must let people delete their account from inside the app. You must declare exactly what data you collect, and it must match what the app really does. Some categories, lending and health especially, have rules that reject an entire business model. None of this is visible until you try to publish.
These two are where "seems to work" costs real money. People stay logged in when they should not, or get thrown out for no reason. Someone pays and gets nothing, or cancels and keeps everything. It passes your test and fails your hundredth customer.
Plenty of apps reach the store once and freeze there, because no one set things up so a small fix can go out next Tuesday. That is the difference between an app that exists and a product you can keep improving.
The question you are probably asking
If AI can write the code, why pay a person?
It is a fair question, and I am not the right person to be precious about it. I use AI tools all day, on my own products, and I am unusually good at them. They are genuinely fast.
But they answer the question you asked. They will not tell you that your idea needs four screens instead of eleven, that the feature you are excited about is the one that will get you rejected, or that you are about to spend three weeks on something nobody will use. That is taste, and it comes from having shipped things and watched what happened next.
And when the store rejects you at eleven at night, or a rule changes in March and your app stops working, there is nobody to call. You cannot escalate to a chatbot. What you are actually buying from me is that somebody is responsible. If it is late, that is my problem. If it gets rejected, I deal with it. If it breaks, you send one message to a person who already knows your app.
How it goes
You are never waiting in the dark wondering what you paid for. The app lands on your own phone early and gets better every week in front of you.
Thirty minutes. You tell me what you want, or show me what you started. I ask the questions that change the price, then I write it all down: what gets built, what it costs, how long, and anything I think is a bad idea.
Not a picture of an app, the actual app, installed on your phone, that you can tap and show to people. Rough in places, but real and getting better.
Accounts and logging in, payments if you need them, the place your data actually lives, and the screens that were still sketches. In the order that removes the most risk first.
Store pages, screenshots, the privacy forms both companies demand, age ratings, the security setup, the release itself. I do the submitting, and I deal with the rejections if they come.
What it costs
Half when we begin, half when the app goes to the stores. No hourly surprises, no monthly retainer you have to remember to cancel.
You have an idea and nothing built. I do all of it.
Half built by an AI tool, a no-code builder, or someone who left.
Already live, and something is wrong or something is next.
Because you are paying one person instead of five. An agency number covers a project manager, a designer, two developers, a tester, and the margin on all of them. For a first version or a rescue, most of that is overhead you are paying for and not using.
The trade is real and you should know it before you decide: I am one person, so I take one project at a time, and I am the wrong choice for something that genuinely needs a full team.
Prices start where they start because the shape of the app decides the rest. What moves it is not the number of screens: it is how many different kinds of user there are, whether money changes hands inside the app, whether it has to work without signal, and whether anything happens live. The call is how we find your real number, and that part costs nothing.
Evidence
Not mockups. Apps you can download right now, with real people using them.
A video app and a product scanner, two different clients, both built and published by me alone inside a month. On the first one the design changed halfway through and the date did not move. This is where the four-week promise comes from. It is not a marketing number, it happened twice.
A company in Argentina needed their staff to fill in reports with photos on industrial sites where there is no signal. I designed it so the app only needs the internet twice a day, and wrote the instructions clearly enough that their own junior developer could build his half correctly. It has been in daily use since April 2025.
A goal-setting app that people pay for, a driving-test app with 459 official questions in three languages, a social app I co-founded. I have been through store rejections, refunds, and one-star reviews on my own products, which is why I can tell you in advance what your launch will actually feel like instead of promising it will be smooth.
Some client apps are published under the client's own name, which is normal and is also how yours will be published. On a call I can walk you through any of them live, including the parts that went wrong.
Everything I have shipped
Four apps of my own, three built for clients, two tools I run and an open-source package. All of them published, all of them openable in the next thirty seconds.
Including the two apps that went from a design file to the App Store in a month each, and the field app that works with no signal at all.
CABA Test · AimYear · Focido · Derivografías · Safety Control · Video & Face Swap Generator · Product Scanner · Worklore · EndpointVault · roller_list
Answers
Written properly, with real numbers, because I would rather you arrive at the call already knowing this. Free to read, no email required.
Who you would actually be working with
I am Valentina. Nine years building phone apps, currently the lead mobile developer at a financial company, where most of my job is fixing things in live apps that other people could not work out. No agency, no juniors doing the real work, no account manager in between. The person on the call is the person building your app.
Before this I taught programming at a technical university for six years. That is why you will get plain explanations instead of jargon, why I will tell you when you are about to waste money, and why what I hand over at the end is written so the next person can read it.
If you are the kind of person who wants to know: I build with Flutter, which is how one build covers iPhone and Android at the same time, and I write the part that stores your data myself, so there is no second contractor to coordinate. If none of that meant anything to you, it does not need to.
Before you book
For a first version built by one person: $4,500 to $6,000 is the usual range here, and the fixed number comes out of the first call. Agencies quote far more because you are paying for a team of five.
Separately, the stores charge their own small fees: Apple is $99 a year, Google is $25 once, both in your name.
Yes, and it is the most common place people start. Bring whatever you have, a sketch on paper, a competitor you like, or just the sentence you use when you describe it to friends. The first call turns that into a real list of what gets built, and quite often makes it smaller and cheaper than you expected.
Sometimes, and I will tell you honestly on the call. If it genuinely only needs submitting, that is a small job and I will price it as one. More often something behind the scenes also has to be fixed before either store will accept it, and I would rather show you that in thirty minutes than discover it in month two.
Then I will say so, and tell you exactly which parts. It usually means one or two pieces, not the whole thing, and I have never seen a project where nothing was worth keeping. You get that assessment free and in writing before any money changes hands.
You do, all of it, always. Your store accounts, everything I write, your data, the lot. I either work inside your accounts or hand everything over at the end, with a guide to publishing the next version without me.
The price is fixed and agreed before we begin, so going over is my problem and not your invoice. If you change what you want halfway, we agree a new number in writing first. Nothing gets billed that you did not approve.
Try it. For something simple the no-code builders and AI tools genuinely work, and if yours is one of those, you have saved money and I will tell you so on the call.
Most people who reach me already tried and got most of the way, then hit the parts that are not really about code: logging in safely, taking payments, and getting past store review. That is the wall, and it is where I start.
Anything that really needs a full-time team, heavy 3D games, and business models the stores will refuse outright, which I would rather tell you in the first thirty minutes than in month three. If it is not a fit I will say so on the call and point you somewhere better when I can.
No charge and no sales pitch. Bring an idea, a sketch, or the half-built thing you are stuck with. You leave with a written plan you can act on, with me or without me.
Book a free 30-minute callOr write to me: vkoniukhova@yahoo.com — I reply within one working day.
