App & Web Development /
Existing App Maintenance
A solo developer with a live, self-built app on the App Store. From concept to implementation and launch, I bring apps and web to life on my own — powered by AI. New builds, plus modernization and feature additions for existing apps, flexibly to your budget.
Gymnastics AI — built and run end to end
An iOS app that automatically calculates gymnastics D-Scores and answers Code-of-Points questions with cited articles via AI. I handled everything from concept and development to release and operation. Not a portfolio demo — a product actually running on the App Store.
Services & Pricing
Mobile App Development
from ¥30,000iOS and Android at once with Flutter. From planning and requirements to implementation and release on the App Store / Google Play.
Existing App & Site Maintenance
from ¥8,000Modernizing outdated Flutter apps, swapping images and text, adding features and fixing bugs. Ongoing, incremental development is welcome too.
Web App & Business System Development
from ¥40,000Web apps and internal systems built with React / Next.js / TypeScript to streamline your operations.
Website & Landing Page
from ¥5,000Websites and landing pages built to your budget.
* Prices are guides from my Coconala listings; each card links to its listing. Anything beyond scope is quoted before we start.
Why work with me
AI-driven, fast & affordable
I use AI heavily throughout development. As an individual without organizational overhead, I can deliver on short timelines at a low cost.
A developer who ships real products
My self-built app "Gymnastics AI", live and running on the App Store, is proof of capability — not a demo, but a product actually in service.
Direct, nimble, bilingual
No middleman fees, no broken-telephone communication. Fast to talk with, in Japanese or English.
Process & pricing approach
Discovery
We discuss your goals, whether there is an existing app, your budget and timeline. Send the source code if you have it.
Estimate (staged)
I review the details and quote light work and full work separately. Scope and price are clear before we start.
Development
Efficient implementation with AI. I share progress as we go.
Review & revisions
You review the deliverable and I adjust within the agreed number of rounds.
Delivery & maintenance
From delivery of build artifacts through to release. Incremental fixes and maintenance afterward are welcome.
Pricing approach
I quote in stages by project — for example, separating "light fixes (image swap / build only)" from "a full modernization". Scope and price are made clear before starting. Anything out of scope is always discussed in advance so costs never balloon.
FAQ
How much does it cost, and how do you estimate?
I quote in stages by project. I separate light work (like an image swap) from full development / modernization, and make the amount and scope clear before starting. Work outside the agreed scope is discussed in advance so costs never balloon.
Can you modify my existing app if I have the source code?
Yes. Send the source code (or the full project) and I will review it, then handle maintenance, modernization, and feature additions. I quote after seeing the current state.
How long does it take?
Light fixes take a few days; full development or upgrades take one to several weeks depending on scope. Let me know if it is urgent.
What about source code and copyright?
Handling of the deliverables (scope of copyright transfer, etc.) is agreed at the time of order, tailored to your needs.
Can you also publish to the App Store / Google Play?
Yes — including store submission and review handling. A store account is required, so let us discuss the details.
Can I request work little by little over the long term?
Yes, ongoing incremental requests are welcome. Once the environment is in good shape, later changes are smoother and more affordable.
How do we communicate? Can I hire you from overseas?
Via Coconala messages or the contact form on this site. I work in Japanese and English, and requests from overseas are welcome.
Let's talk about your app
"I want to build an app like this" or "I want to fix this old app" — even a rough idea is perfectly fine.
