About MarginLog

Why we built this

Every reseller knows the problem. You sell something on Poshmark for $45 and think you made $45. Then you subtract the 20% platform fee, the $8 you spent on shipping, and the $12 you paid at the thrift store — and you made $18. Or maybe less. You're not really sure.

Most resellers track their numbers in spreadsheets they build from scratch, or don't track at all. The apps that exist are either built for professional businesses (too complex, too expensive) or don't account for what fees actually are on each platform.

MarginLog was built to fix that. Log a sale in 30 seconds, see your real profit immediately, and over time understand which platforms and categories are actually making you money.

What MarginLog does

• ✓Calculates true net profit after platform fees, your shipping cost, and cost of goods
• ✓Tracks every sale across eBay, Poshmark, Mercari, Depop, Facebook Marketplace, Vinted, and Etsy
• ✓Shows you which platforms and categories perform best over time
• ✓Exports your full sales history to CSV — useful at tax time
• ✓Keeps fee tables current so you always get accurate numbers

What MarginLog doesn't do

MarginLog is not accounting software. It is not a tax filing tool. It is not a crosslisting tool. It does one thing well: tells you your real profit on every item you sell, and shows you trends over time. If you need more than that, you likely already know what you need.

Who it's for

Casual resellers who sell a few items a month and want to stop guessing. Intermediate resellers running a side hustle who need to understand their margins. Anyone who has ever sold something online and then tried to remember what they actually paid for it.