Saifullah AhadHow I built it
Atrekes: Used Phone CheckLive on Google PlayAtrekes: a used-phone check the buyer can trust
Used Phone Check, live on Google Play. The phone being sold tests itself — and hands the buyer a signed result.
01
The problem
A used phone can cost a month's wages, and the buyer gets five minutes on a footpath to decide. A battery that has lost half its life looks new. A dead patch on the touchscreen passes if you never touch it there.
02
The plan I wrote
The app runs shop-style checks on the phone being sold — touch, screen, battery capacity, storage and sensors — and warns when the phone's software has been tampered with.
Then the seller's phone passes the result to the buyer's phone through a QR code, signed, so the buyer knows it came from that phone and is not a screenshot of a better one. It never prices the phone, never rates the seller, and never says whether to buy.
03
The build
AI coding agents built it from my written specification. My work was the specification, the tests it had to pass, and the review.
04
The proof
On a real phone — a Samsung Galaxy Z Flip4 on Android 16 — the signed release build ran the full seven-part check twice from a cold start: all 96 touch cells, six live sensors, battery capacity, storage and every screen, with zero crashes in the logs.
When the app had no reference data for that phone model, it said so plainly instead of inventing a match.
05
The launch
Live on Google Play, with its store listing, privacy page and screenshots for phones and tablets.
What this shows about how I work
- Trust is designed in: a signed result the other person can check.
- Honest by default: "I don't know" beats a made-up answer.
- Proven on real hardware, not only in a simulator.
How to check a used phone before buying
You often get only a few minutes with a second-hand phone. These are the checks that matter most:
- Battery. Look for battery health or capacity in the phone's settings. A phone that drains fast or gets hot while idle has a worn battery.
- Touchscreen. Drag one finger slowly over every part of the screen. A dead patch only shows up where you actually touch.
- Screen. Open a plain white and a plain black picture and look for dead dots, shadows of old images or uneven color.
- Buttons, ports, speaker, microphones and cameras. Press every button, plug in a charger, make a short call and take a photo with each camera.
- Sensors. Turn the phone to check auto-rotate, and try the fingerprint or face unlock.
- Lock and ownership. Make sure the seller has signed out of their account, so the phone is not locked to them. Dial *#06# to see the IMEI and compare it with the box.
Atrekes runs shop-style checks like these on the phone being sold, warns when its software has been tampered with, and passes a signed result to the buyer's phone. It never prices the phone or tells you whether to buy.
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