DEVELOPMENT NOTES
Notes from building small tools
English guides on automation, apps and the details that keep small tools useful.
How Much Does Adding AI Cost? Estimate Usage Before You Build
Estimate AI usage alongside setup, maintenance, subscriptions and connected services. Start with a small sample and a spending limit; check current provider rates before adding an API.
Automating Your Work with Google Apps Script — The Complete Guide
How to automate repetitive work — orders, bookings, inventory, settlement, field input — with Google Apps Script (GAS). What it does, how far it stays free, and where it hits limits, in one place.
Export CSV from Google Sheets without losing IDs or breaking notes
Use the values people see, quote commas and line breaks correctly, and import identifier columns as text so leading zeroes survive.
Apps Script triggers: 6 traps that make a script run twice, late, or not at all
Simple onEdit vs installable triggers, the 9 AM trigger that runs at 9:40, stacked triggers, and the Status column + lock pattern I use so a repeat run never sends anything twice.
ARRAYFORMULA in 2 minutes: 5 one-liners and the traps that fill your sheet with zeros
One formula in row 2 that fills the whole column: totals, labels, auto IDs, buckets and checks. Every formula ran in a real Google Sheet, including the ones that go wrong.
The Awkward Problems in Calendar-Based Attendance Tracking
The awkward audit, approval, and exception-handling problems that appear when Google Calendar becomes attendance tracking.
ChatGPT API Costs Quietly Leak Money If You Do Not Count Them
Why ChatGPT API bills quietly grow, and how token tracking, caching, retries, and model routing keep them under control.
How a Multi-User Inspection App Is Different
A single-user app just needs a screen. An inspection app where several people write the same data hinges on sharing, collisions, and reports. Even so, narrow the scope and you can start with GAS, Sheets, and Drive at no running cost. The fictional browser demo is being rebuilt.
Bad Form Auto-Replies Damage Customer Trust
When form auto-replies damage customer trust, and what response rules should be set before automation.
Preview Google Sheets imports by ID before adding order rows
Compare incoming orders with the sheet by a stable business ID, surface duplicates and conflicts, and review every candidate before anything is written.
Google Sheets QUERY cheat sheet: 8 strings I reuse, 4 traps that return nothing
Filter, sort, total per customer, mini pivot and date ranges with QUERY. Every formula ran in a real Google Sheet, including the ones that fail quietly.
A habit tracker that can leave the app: check-ins to CSV
Try Habit Streak, export a dated CSV, and count check-ins in Google Sheets. Fictional friends, local storage, and a clear boundary between export and sync.
Your Dashboard Refreshed. Did Its Source Data?
Separate page refresh time from source freshness. A fictional inventory example, timestamp contract, and failure drills keep old numbers from appearing current.
Outsource vs Build vs SaaS: Compared by Cost
Compare subscriptions, a self-built workflow and a commissioned tool using setup, time, maintenance and ongoing service costs. The cheaper option depends on the scope and expected use.
Cut Your Monthly SaaS Bill: Rent vs Own Your Automation
A custom Apps Script workflow may replace a subscription, but setup and upkeep still matter. Compare total costs, current quotas and connected services before switching.
How One Shared Sheet Link Leaks Company Data
How one shared Google Sheet link can leak company data through permissions, copies, and forgotten access.
Shift Swap: ask from your phone, one tap to approve, the roster fixes itself
A small mobile web app for shift trades: staff request a swap, the manager approves once, and both shifts move together. Plus how I'd hand it to Google Sheets.
Inventory in Google Sheets: How Far Automation Goes
One store or warehouse: stock in/out, low-stock alerts, and settlement is fine with Sheets automation. Tens of thousands of SKUs and real-time multi-site is the limit.
Tap Ledger: log a coffee in two taps, total it in Sheets
A small expense app with presets, a month view and on-device receipt reading. Export to CSV and rebuild the same monthly totals in Google Sheets with SUMIFS.
Apps Script Costs: No Separate Server, but Plan for Upkeep
An Apps Script workflow may avoid separate server hosting charges. Check account quotas, subscriptions, connected services, setup and maintenance before estimating its total cost.
XLOOKUP vs VLOOKUP in Google Sheets: the 2-minute version
Lookups I ran in a real Google Sheet: where VLOOKUP quietly returns the wrong value, and the XLOOKUP version that doesn't.