Case Study
Hey Hazel
Building a custom operations app for my reselling business.
App status: In active use · In development
Hey Hazel is my reselling business. To support its operations, I’m building a custom app for managing inventory, preparing listings, and tracking sales. I use the features I’ve built through the app interface while continuing to develop the product.
Built on Google
Google Apps Script powers the application, Google Sheets holds its records, and Google Drive stores item photos. Gemini supports AI-assisted listing preparation, while a custom Chrome extension connects the app to marketplace listing workflows.
From inventory to sale
The app connects item intake, barcode workflows, photos, listing preparation, and sales tracking. As both the business owner and app builder, I can identify operational needs firsthand and use them to guide development.
Hey Hazel / The business numbers
What the records show.
– · USD
Published snapshot
Updated
Actual resale records, with their limits visible. Recorded proceeds account for the costs below; they are not cash collected or a complete measure of net profit.
- Sales value
- $884.64
- 157 recorded sales · before costs
- Recorded proceeds
- $859.88
- After recorded selling and item costs
- Reported API cost
- $1.21
- Google AI Studio · project total
- API reporting period
- Aug 29, 2026 – Sep 25, 2026
- Different periods; no combined total
Proceeds over the period
Recorded proceeds / dayView daily figures
| Date | Recorded proceeds |
|---|---|
| $26.00 | |
| $95.50 | |
| $20.45 | |
| $6.80 | |
| $14.00 | |
| $48.95 | |
| $22.50 | |
| $60.80 | |
| $9.00 | |
| $12.00 | |
| $54.40 | |
| $27.00 | |
| $37.40 | |
| $1.00 | |
| $52.00 | |
| $89.30 | |
| $10.00 | |
| $24.00 | |
| $12.16 | |
| $1.80 | |
| $19.20 | |
| $2.00 | |
| $5.00 | |
| $39.02 | |
| $10.00 | |
| $29.00 | |
| $4.74 | |
| $4.00 | |
| $15.00 | |
| $22.75 | |
| $2.00 | |
| $30.48 | |
| $23.62 | |
| $10.76 | |
| $13.00 | |
| $4.25 |
Recorded isn’t the same as paid.
$5.00 in proceeds belongs to 1 sale marked paid. 156 sales are not marked paid. These are record statuses, not a bank reconciliation.
From sales to recorded proceeds
- Sales value
- $884.64
- Shipping charged
- $0.00
- Refunds
- -$0.00
- Recorded selling costs
- -$24.76
- Recorded item costs
- -$0.00
- Consignor payouts
- -$0.00
- Recorded proceeds
- $859.88
Other expenses recorded: $0.00. Expense coverage is unconfirmed; this does not establish that no other expenses exist.
Cost basis matters.
157 sales have zero recorded item cost, including owner possessions assigned zero resale basis. This is not a claim that acquiring those items originally cost nothing. 157 sales use estimated platform fees.
API cost has a boundary.
$1.21 reported for Aug 29, 2026 – Sep 25, 2026, observed Sep 25, 2026. It is a project total; exclusive attribution to this app is unconfirmed, so it is not deducted from proceeds here. Billing can lag by up to 24 hours.
Inventory return
Not established
Not applicable: these sales have no recorded resale inventory investment. Existing belongings were not necessarily free to buy originally.
Return on building the app
Not yet measured
Not yet measured: development time, operating costs and attributable benefits are not fully recorded. Sales proceeds alone do not measure what the app added to the business.
Still evolving
Upcoming work includes automated delisting, richer financial and sourcing insights, improved pricing controls, and support for more marketplaces.