Your app idea. Built in 21 days.

Quoted $10,000 to $500,000 for your app idea?

We build yours for $5,000. Fixed.

One new project a month.

Liquid chrome and red flowing into a row of iPhones

Your app idea is still in your Notes app.

You’re a full-time professional, and you have an app idea you can’t stop thinking about.
You’d build it tonight, but you’re not technical and you don’t have a technical co-founder.
One agency quoted you $10,000, another $50,000, and you can’t tell which one is honest.

And you’ve heard the stories: the developer who disappears halfway, and the founder left with a half-finished app and an empty bank account.

So the idea stays in your Notes app, and your 9-to-5 stays your life.

We build your app for you, from the first screen to the App Store.

You don’t need to know anything technical, and the app and its code are 100% yours.

We build it for you in 21 days, for a fixed $5,000.

Tell Us Your IdeaI personally review every application.

An idea today. A real product 21 days later.

From one sentence to a working iPhone app.

Day 1

“What if there was an app that showed me every available padel court nearby and let me book one instantly?”

That’s enough to start.

Your idea doesn’t need to arrive as a specification.

You don’t need wireframes.
You don’t need technical knowledge.
You don’t need to know what database to use, which API you need, or how the app should be architected.

You just need the idea.

We take it from there.

21 days later

Your app, live on the App Store.

A real app you can show users and investors, not a demo.

Apply to Build Your AppI personally review every application.

The Founder

One person responsible for getting it done.

You work directly with me, from the first call to the App Store.

Joseph, founder of Cortexity, at his desk

Hi, I’m Joseph, founder of Cortexity. I design and build mobile apps for founders, from the first call to the App Store.

Before building apps for others, I built my own. I’ve been the client myself and felt the delays, the vague answers and the “that wasn’t in the scope”. That’s why Cortexity exists.

When I take on your app, I take responsibility for getting it built. You shouldn’t have to project-manage your developer or understand the technology. You should feel free to change your mind when the product could be better.

For 21 days we work on one goal: the best first version of your app we can build.

And yes, I’m the one who answers your messages.

What’s Included

Everything between the idea and the App Store.

Product, design, development and launch, handled by one person.

Product
We turn what’s in your head into a first version worth building.
Design
Every screen and every interaction, designed so you’re proud to put your name on it.
Development
App, backend, database, APIs. You never need to know what any of it means.
Refinement
You see it as it’s built. Change your mind as often as you like. No hourly bill.
Launch
We submit it to the App Store and stay with you through review.

Built by Cortexity.

A few of the apps we’ve built, live on the App Store today.

SLOWR

A men’s wellness app with step-by-step training programs, progress tracking and a monthly subscription, all in one place.

ReflexFlow

A wellness app for women: a multi-week program they follow from their phone, with guided audio sessions and progress tracking.

The Process

What the next 21 days look like.

1
Week 1
We understand the idea.
- We talk through the idea, who it’s for and how you imagine it working, then start designing.
- We define the main features for version one.
- First screens on your phone by the end of the week.
2
Week 2
The app starts working.
- The core of the app works on your phone.
- You use it every day and tell me what feels wrong.
- We change it. Nothing extra to pay.
3
Week 3
We polish it and submit it to the App Store.
- Refinement and polish, together.
- App Store submission, handled with you.
- The app, the design, the code: yours.

No Scope Creep

No “that’s outside the scope” every time you have an idea.

Changing your mind is part of building something good.

A product you imagined three weeks ago won’t always be the product you want after you’ve actually seen and used it.

For the 21 days we’re working together, you’re not going to be charged every time you ask us to change a button, rethink a screen or improve how something works.

Ask for changes as often as you like.
There is no awkward conversation because you’ve used your allotted number of revisions.
If you ask for a big change that needs more time, we’ll adjust the timeline together.

But our default response to a better idea isn’t:

“That’s outside the scope.”

It’s:

“Let’s figure out how to make it work.”

Who It’s For

This is for professionals with an app idea they can’t stop thinking about, and are ready to launch it.

Cortexity is for you if you already know what your app should do, and you want it built right the first time.
You don’t need to be technical.
You don’t need to have founded a company before.

You don’t even need to have every detail figured out.

But you do need to show up.

We want founders who answer messages, give feedback, make decisions and genuinely want to see their product exist.

In return, you’ll get that same commitment from me.

We deliberately take on very few projects because when we’re building yours, we want to be all in.

If you’re casually exploring an idea, looking for the cheapest possible developer, or collecting ten quotes before deciding whether you even want to build anything, we’re probably not the right fit.

If you’re thinking:

“I want to finally build this properly.”

Then we should talk.

Tell Us What You Want to BuildI personally review every application.

Pricing

$5,000. Start to finish.

One fixed price, paid in two halves.

No hourly rate, no separate designer, and no bill that grows every time you ask for a change.

Your Cortexity build: $5,000

$2,500 to start.

$2,500 when your app is finished.

iPhone

$5,000

Product strategy
Full app design
Development
Backend, database & APIs
Testing
Refinement throughout the build
App Store submission
Full ownership of the app and code

Apply to Build Your AppNo payment until we’ve spoken and both said yes.

iPhone + Android

$8,000

Product strategy
Full app design
Development
Backend, database & APIs
Testing
Refinement throughout the build
App Store submission
Full ownership of the app and code
Android built as a second phase

Apply to Build Your AppNo payment until we’ve spoken and both said yes.

Before you pay anything, I’ll talk with you about your idea.

I’ll make sure I understand what you want to build and that Cortexity is the right studio for it. If it isn’t, I’ll tell you.

FAQ

Questions you probably have.

Straight answers to what founders ask first.

Why are other quotes so much higher?

Agencies quote for big teams, long timelines and open-ended scope.

We build one focused first version in 21 days, for one fixed price, and you own all of it.

Can you really build my app in 21 days?

Yes. Before we start, we agree exactly what the first version includes, so 21 days is enough.

What if I change my mind about something halfway through?

That’s expected. Changing your mind is part of the process.
During the 21 days, we’ll keep refining the product with you. You’re not going to receive an extra invoice because you wanted a screen redesigned or realized something should work differently.
If you make a major change that affects the 21-day timeline, I’ll tell you right away and we’ll adjust the delivery date together.

What happens after the 21 days?

Once the build is complete, the app is yours.
We’ll then handle the App Store submission process with you.
Want to keep building after that? New features and bigger updates are a new project, priced on its own.
You’re not locked into Cortexity.

What if something breaks after the project?

If something we delivered isn’t working the way it’s supposed to, we’ll fix it.
We’re not going to hand you the app on Day 21 and pretend we’ve never met.
For new features, redesigns or continued product development after the initial project, we simply start a new project together, billed separately.

Can you build Android too?

Yes. iPhone is $5,000. iPhone plus Android is $8,000.
We build the iPhone app first, then the Android version, so each one feels native.
Tell us in your application if you want both.

Is App Store submission included?

Yes.
We handle the submission process after the 21-day build.
Apple controls the review and approval process, so the time Apple takes to approve an app isn’t counted as part of the 21 days.
If Apple comes back with something that needs addressing, we’ll work through it until the app is live.

Do I own everything?

Yes.
Once the project is completed and the final payment is made, the finished app, code and project are yours.
It’s your product.

How is payment made?

By bank transfer or a secure Stripe payment link.
In Lebanon, you can also pay via Whish.
The project starts once the 50% deposit is received.

Do I need to know anything about building apps?

No.
You know the idea, the customer and the problem you’re trying to solve.
We take care of the rest.

Three weeks from now, this could be on your phone.

Imagine handing someone your phone and saying: this is my app.

If you have an app idea you’re serious about, tell us about it.
I’ll personally review what you send.
At the end of the application, you book a call with me to talk it through.

Built in 21 days, for a fixed $5,000.