Engineer's notebook
ArjavJain
I design the system, then I build it: Flutter apps, Next.js products and AI features. This is where I write down how each one is put together.
13 projectsFlutter + Next.jsBased in India
The cat says: Hi! I build apps. Want one built? Flutter, Next.js and a bit of AI. Ask me how it is built.
01 / What I do
One person, four jobs, one system.
I work directly with the people who need the software, from the first whiteboard to the deploy. No account managers in between.
- 01
Software developer
Flutter, Next.js and TypeScript. Code that ships, tested and handed over clean.
- 02
System designer
Flows, data and boundaries drawn before the first line is written, so cost and scope stay honest.
- 03
Solution architect
The stack and the shape that fit the business, not the trend of the month.
- 04
Forward deployed engineer
Embedded with the team, making it work in the real world and not only in a demo.
Studied B.Tech in CST at MAIT Delhi. Builds Flutter apps, Next.js products and AI features. My partner Sachin Sharma writes the buyer's guide at bestdev.in.
02 / Build log
Thirteen things I have built, and how.
Each row opens to how it is put together. Six are shipped products; the other seven are apps and tools with their code, or a showcase of it, on GitHub. Open one.
01LoopinFlutter appA gamified habit tracker that mixes RPG mechanics with data you own.
How it is put together
- Offline-first: everything is stored on the device with Hive.
- Sync goes to the user's own Google Drive.
- Screens for daily habits, stats and a head-to-head rivals view.
FlutterHiveGoogle Drive syncProduct
02LegeaseFlutter appAn AI legal-document platform: clause breakdowns and risk spotting for contracts.
How it is put together
- Built as a Flutter app around document analysis.
- Clause breakdowns and risk identification are the core flow.
- The app also holds an agreement history and a list of lawyers.
FlutterNLPAI legal techProduct
03AashwasanFlutter appA gig and contract management app with real-time order tracking and secure communication.
How it is put together
- Flutter on the client, Firebase behind it.
- Orders are tracked in real time.
- Agreements are shown as cards on the home screen.
FlutterFirebaseGig economyProduct
04WallyFlutter appA gesture-driven ultra 4K wallpaper library with infinite scroll.
How it is put together
- Infinite scroll over a large image library.
- Smart local caching of the images.
- Browse by category or by colour.
FlutterCachingUI/UXProduct
05EHR CopilotNext.js toolTurns psychiatric session transcripts into structured SOAP notes.
How it is put together
- Next.js front end for the clinician.
- A transcript goes in, a structured SOAP note comes out.
- A report view and a verification screen sit next to the notes.
Next.jsGenerative AIHealth techProduct
06MojoDocsWeb platformA privacy-first utilities platform running 1,100+ file tools locally.
How it is put together
- WebAssembly does the work in the browser.
- Tools run locally, on the device.
- A drop-a-file home page leads to the tools, PDF tools among them.
WebAssemblyNext.jsLocal-firstProduct
07MojoPlayFlutter appA music app built around listening with people.
How it is put together
- Listen Together sessions run over a live socket.
- Mood-based discovery, background playback and offline downloads.
- Public showcase repository; the source is closed.
FlutterRealtime syncMusicShowcase repo
See it on GitHub08DailyFlutter app + APIA current-affairs and quiz app for exam aspirants.
How it is put together
- A daily brief, streaks and quizzes in Flutter.
- Backed by its own Next.js API and admin dashboard.
- Prisma and SQLite hold the data.
FlutterNext.jsPrismaShowcase repo
See it on GitHub09DevDexmacOS appFinds every project you have started and opens it in the right IDE.
How it is put together
- Native Swift. It scans folders and reads each manifest to learn the project's real name and type.
- An Env Vault sits behind Touch ID.
- No network access, no accounts, no telemetry. A Windows port exists.
SwiftmacOSDeveloper toolsSource available
See it on GitHub10MojoCinemaFlutter appMovie discovery without the ad clutter.
How it is put together
- A trailer hub, search, actor pages and a local watchlist.
- Indian and regional titles are ranked first.
- Data comes from a public catalog API.
FlutterUI/UXPublic APICode on GitHub
See it on GitHub11SameframeDesktop appFinds exact and similar photo and video copies on your own machine.
How it is put together
- Exact duplicates: SHA-256, then a byte-for-byte compare.
- Visually similar media is surfaced with DINOv3 and V-JEPA 2, for manual review only.
- No uploads, no account, no telemetry.
Next.jsElectronLocal AISource available
See it on GitHub12FlashDropLocal web appPrivate phone-to-Mac file transfer over the same Wi-Fi.
How it is put together
- The Mac hosts a local Next.js receiver; the phone scans a QR code and sends from its browser.
- Files go in 8 MiB chunks, each encrypted with ChaCha20-Poly1305.
- Retry and resume are built in. LAN only.
Next.jsLAN onlyEncryptionSource available
See it on GitHub13One Tap RecorderAndroid appAn Android screen recorder you start from a home-screen widget.
How it is put together
- 4K at 60 FPS, with ordered fallbacks when a device cannot.
- Device audio and microphone.
- No accounts, no ads, no analytics, no network access.
KotlinFlutterAndroidOpen source
See it on GitHub+ / Client and academic work
Five folders that stay closed: the code and the details belong to the people I built them for. What I can say is what each one is.
- Client
Ralas One
A multi-brand two-wheeler dealership management platform: OTP login, an owner panel and a sales pipeline from enquiry to quotation.
Next.jsPostgresDrizzle
Owner panel and login are database-backed; the other department panels are being wired in order.
The client's details stay private.
In progress - Client
Ralas Group website
The website of a diversified business group headquartered in Raipur, covering real estate, automobile retail and electric mobility.
Next.jsVercel
The client's details stay private.
Live - Client
Ather dealership, Raipur
The scooter range, test-ride booking, finance options and dealership contact for an authorized Ather dealership.
Web
The client's details stay private.
Live - Client
Project Rho
An agentic investing environment for India: eleven specialist agents and an orchestrator stage orders, and the user's tap is the final say.
WebAI agents
The client's details stay private.
Live - Academic
MediChain
A health-memory and drug-safety platform with separate patient and doctor apps, built in a team of three at MAIT.
FlutterRiverpodPostgreSQL
Patient flow runs on mock records; the doctor workflow is in progress.
The client's details stay private.
Prototype
03 / Proof
The largest thing, in numbers.
A real-time multi-tenant platform for a family-run conglomerate across automobile, retail and real estate. The revenue figure is the client's own.
- tools in MojoDocs
- 1,100+all running locally in the browser
- brands on one platform
- 5built for a family-run conglomerate
- outlets connected
- 8one real-time system
- annual revenue
- ₹150 Cr+of that conglomerate, as reported by the client
04 / How I work
Listen, draw, walk it through, build.
The job starts before the code: what to build first, what to leave out, and what a fair quote looks like.
- 01
Listen
You tell me the idea over a call. I ask what you have not thought of yet and write it down.
- 02
Draw
I send a free flow diagram: who does what, in what order. It is yours to keep, whether or not we work together.
- 03
Walk it through
We go through the flow, fix what is wrong, agree what comes first and park what can wait for version two.
- 04
Build
We build in milestones you can test, not a lump sum and a long wait.
- A website is enough, often. If your idea does not need an app, you will hear that from me, even when it makes the project smaller.
- No quote without a written scope. Screens, features, what is not included, and milestones you can test. If it is not written down, it is not priced.
- I am one developer. For a big team or round-the-clock operations I will say so plainly, and tell you who else to bring in.
05 / Notebook
Guides and write-ups, in one place.
Projects 6 pages
- Aashwasan: what was built and howIt helps freelancers and small service providers create contracts, track orders in real time, and communicate securely with clients. The app solves the pain of managing.
- EHR Copilot: what was built and howIts core function is documentation automation, not diagnosis or treatment advice. It generates notes in the SOAP format, which are used in clinical documentation.
- Legease: what was built and howLegease helps small businesses quickly review contracts by pulling out key terms and tracking deadlines. It solves the problem of spending too much time reading long.
- Loopin: what was built and howLoopin is a mobile habit tracker app built with Flutter that helps you build good habits over time. You can track any habit, like drinking water, walking daily, or.
- MojoDocs: what was built and howMojoDocs helps you edit, compress and convert files like PDFs, images and invoices without sending them over the internet. It is for small-business owners, clinic staff.
- Wally: what was built and howWally is an open source Android app that lets you browse and set wallpapers from Wallhaven. It gets images by scraping Wallhaven’s website, so you do not need to log in..
Case studies 1 page
Services 2 pages
- App rescue and takeover: what you get and how it worksApp rescue can stabilise your app in 30 to 60 days and costs less than rebuilding. It works if the code has structure but is broken or slow. Not for apps with spaghetti.
- Do you need a mobile app for your business?A mobile app is worth building only if your customers use it weekly to order, book or track—and need offline access, alerts or camera use. Otherwise, start with a website.
Cost guides 10 pages
- How much does an app cost for a small business?Most small business apps cost ₹7 to ₹25 lakh to build, with ₹3–5 lakh as a lower limit for a tight MVP. You will pay 15 to 20% of the build cost yearly to maintain it..
- What does a clinic booking app cost?A custom clinic booking app costs ₹1.5 lakh to ₹10 lakh, depending on features like online payments, admin dashboards, and cross-platform support. Most small clinics in.
- How much does a cloud kitchen app cost for a small business?A custom cloud kitchen app costs ₹2.5–30 lakh, plus 18% GST, depending on features. A white label app starts at ₹1.5 lakh. You need it if you want full control and better.
- How much does a grocery delivery app cost for a small business?A basic grocery delivery app costs ₹3.5 to 7 lakh for one shop in a town or city. This covers a simple order and payment flow. The cost can rise to ₹15 lakh or more if.
- How much does a meat and fish delivery app cost in India?As an estimate, assuming $20,000 to $80,000 at ₹82 per dollar, a basic meat and fish delivery app costs ₹18 to 65 lakh. It must include cold chain tracking, weight-based.
- How much does a milk and dairy delivery app cost for a small business?A milk and dairy delivery app costs ₹3.5 lakh to ₹9 lakh for a small business with 100 to 500 customers. The final price depends on whether you add route planning,.
- How much does a quick commerce app cost for a small business?A single-city quick commerce app costs ₹20 to ₹40 lakh to build. This covers the customer app, rider app, store tool, and admin panel. It is for small-business owners.
- How much does a Flutter app cost for a small business?A Flutter app for a small Indian business costs ₹1.5 lakh to ₹15 lakh, depending on what it must do, not the technology used. This range covers apps with user login,.
Hiring guides 7 pages
- How do I hire a developer as a non-technical founder?You can hire a good developer without knowing code by focusing on clear goals, proof of past work, and checks for trust and ownership. A simple app costs ₹4 to 8 lakh..
- How do I choose a developer for a clinic booking app?You can hire a solo developer or small team for a clinic booking app, but only if they show proof of past clinic work, sign a contract for full ownership of the code, and.
- How do I choose a developer for a coaching institute app?Only build a custom coaching app if tools like Teachmint or FeeAlert no longer meet your needs. The developer must sign that you own the code. Most small centres save.
- How do I choose a developer for a diagnostics lab app?For a diagnostics lab app, hire a developer who understands sample tracking, data privacy, and report workflows. The app costs ₹35 lakh to ₹90 lakh for a lab handling 50.
- How do I choose a developer for my small business website?You need a developer who gives you a GST invoice, a simple agreement, and full ownership of your website. Make sure your domain is in your name and you get access to.
- How to hire a Flutter developer for your first appHire a Flutter developer only if they show a shipped app, give a written scope with inclusions and exclusions, tie payments to testable milestones, and put all code and.
- How do I hire a Next.js developer for a web product?As an estimate, assuming a developer works full-time and charges based on market rates in India, a Next.js developer may cost ₹50,000 to ₹3,00,000 per month. Hire one if.
Comparisons 4 pages
- App or website first: which is right for a small business?A website works when you have internet, but most cannot do anything offline. An app can work even without a network, like taking orders during a power cut. But an app.
- How to choose the best app development company in IndiaThe best app development company for you matches your project size, budget and need for control. Most small businesses do best with a small studio that shows proof of.
- Freelancer or agency for a first app: which is right for a small business?An app is a program you install on your phone or tablet to do a specific job. Like booking clinic visits or tracking shop inventory. Unlike a website, which you open in a.
- Native or cross-platform: which one for your app?A native app is built for just one operating system, like iOS or Android, using its own tools and languages. For iOS, developers use Swift or Objective-C with Apple’s.
More pages are written and checked before they appear here. My partner Sachin Sharma writes the buyer's side at bestdev.in.
06 / Questions
What people ask before the first call.
Freelancer or agency for a first app?
For a first app with a clear scope, one developer you talk to directly is usually faster and cheaper, because nothing is lost between an account manager and the person writing code. An agency makes sense when you need several disciplines at once and someone to manage them.
Do I need a native app, or is a website enough?
If people need it offline, push notifications or the camera, build an app. If they only look something up or book something, a fast mobile website is cheaper and easier to find on Google.
How do I judge a quote?
A fair quote lists what is included and what is not, splits the price by milestones you can test, and says how changes are handled. One lump sum with a vague scope is where projects go wrong.
What happens if we stop midway?
You should be able to walk away with the code and accounts built so far. Ask for this in writing before you pay anything, from anyone you hire.
What should I have ready before the first call?
One sentence on who it is for and what problem it solves, two or three apps you like, and what has to work on day one. You do not need designs or a feature list.