04Case study
Civil Site Calculator
Mobile app · Construction utility
Offline calculators for Indian site engineers and contractors — concrete, steel, brickwork, plaster, tiling and BOQ estimates, in English and Hindi.
How it’s built
From the project’s source code
01Smart input
Optional AI assistant
→ Calculators, Gemini API
02Secure storage
Key never in the bundle
→ Gemini API
03Calculators
Concrete · steel · brick · BOQ…
→ Riverpod
04Gemini API
User-supplied key
05Riverpod
Inputs · results · settings
→ Drift (SQLite)
06Drift (SQLite)
Projects · history · rates
→ Export
07Export
Branded PDF · Excel · share
- calculators, from concrete mix to residential BOQ
- 11
- languages — English and Hindi
- 2
- test files
- 13
A toolkit of construction calculators — concrete mix, rebar weight, brickwork, plaster, tiling, excavation, RCC slab steel, electrical load and residential BOQ — with saved projects and shareable estimates.
The problem
Site estimates are often worked out by hand or on generic calculators, on sites with patchy connectivity, and then need to be shared as a professional document.
My role
Solo developer — calculators, data model, localisation, export formats, AI integration and Play release under J-Tech Utilities.
Technical approach
- Flutter with Riverpod and GoRouter; calculations, projects and history stored locally in SQLite via Drift.
- PDF and Excel export with branded output, shared through the system share sheet.
- English and Hindi UI with Noto Sans Devanagari so exported documents render correctly.
Engineering decisions
No secrets in the app bundle
AI is opt-in: users add their own Gemini API key, which is kept in platform secure storage and never shipped with the app.
Offline is the default
Every calculator works without a network; only the optional AI assistant ever leaves the device.
Status
Published on Google Play for Android; the latest update shipped in October 2026.
Gallery
ArtworkStore feature graphic