I write the Android software 120 branches count their stock with.

Stock counting, receiving, transfers, batch picking and store-to-store approvals for four roles: branch, warehouse, distribution and audit. The role you sign in with decides which screens exist at all.

Counted lines go into the phone's own database and stay there until the ERP accepts them. A dropped connection mid-aisle costs nobody their count. Sign-in works offline too, against users synced to the handset, with bcrypt hashing running in a background isolate so the screen doesn't freeze.

Built since August 2026

• A report queue for unscannable barcodes. It works out the cause from what the scanner actually saw (a damaged label, or an item missing from the ERP) instead of from the counter's answer, which proved unreliable.
• Expected stock per branch, cached and usable offline. If a unit conversion isn't certain, it shows the ERP's own figure rather than a wrong one.
• A minimum-version gate that blocks outdated builds without locking out phones that are offline.
• Sentry monitoring of errors and failed uploads, tagged by branch, role and workflow, with no personal data.

Branch staff photograph the bank deposit slip. The phone reads the bank, reference number, amount and date itself, and staff confirm the fields instead of typing them. It works on BDO, BPI and PNB slips.

Before this there was no system. Head office could not check a deposit until the paper slip arrived. Now it gets the slip the same day it's deposited.

The minute-long sign-in

Sign-in on the cheap phones branches use took about a minute. The network looked guilty, but it wasn't: the API answered in 41 ms. The real cost was password hashing, at about 1.9 seconds per hash, run for all 133 cached users before anyone could sign in.

I measured the hashing speed on the phone itself, removed the step that hashed everyone before sign-in, and set the work factor to 25,000 iterations, writing down the trade-off. Hashes now migrate both ways, so phones already in branches got faster too. Sign-in now takes under a second.

A warehouse picking app for stock transfers, replacing the transfer module of an old desktop app. Pickers scan in the aisles, a checker verifies every pick before it's submitted, and each transfer records who did both.

Before building anything, I audited the old system and found two production bugs. A quantity check read the requested amount instead of the remaining amount, so a half-picked line could be picked again past its total. And on a slow connection, tapping submit twice created two real stock documents.

The new app scans barcodes with the camera against an offline list of about 7,000 items, shows quantities in the checker's own unit, offers batches by nearest expiry, and posts to the ERP with retry. Each submission gets a key on the phone that is resent on every retry, and a pending-post record survives the app being killed between submit and post.