Data and automation engineering, built into the stack you already run. We find what is costing you, ship the fix, and hand it over. You own it.https://otum.ioen-gbhttps://otum.io/blog/when-do-you-know-your-holiday-profithttps://otum.io/blog/when-do-you-know-your-holiday-profitReturns, chargebacks and late bills keep changing holiday profit into the spring. When each one settles, and how to close the season per order.Thu, 15 Oct 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/amazon-vendor-central-vs-seller-centralhttps://otum.io/blog/amazon-vendor-central-vs-seller-centralSeller Central takes a published fee, shipping included. Vendor Central takes its share through terms nobody publishes. How to work out which leaves you more per unit.Mon, 12 Oct 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/where-to-find-shopify-billshttps://otum.io/blog/where-to-find-shopify-billsYour Shopify bills are in Settings, Billing, one PDF at a time. What each charge is, why there are so many, and how to get them all into the books.Thu, 08 Oct 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/1099-k-does-not-match-bookshttps://otum.io/blog/1099-k-does-not-match-booksA client's 1099-Ks are gross by design and each processor dates a late December sale differently, so reconcile each form to its own export before the return.Mon, 05 Oct 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/does-shopify-collect-and-remit-sales-taxhttps://otum.io/blog/does-shopify-collect-and-remit-sales-taxShopify collects US sales tax but no longer files it for new stores. Who does, what Shopify Tax and Avalara cost, and how to choose.Thu, 01 Oct 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/amazon-account-level-reserve-deferred-transactionshttps://otum.io/blog/amazon-account-level-reserve-deferred-transactionsHow long Amazon holds your money, how deferred transactions differ from the account level reserve, and how to forecast when the money reaches your bank.Mon, 28 Sep 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/how-much-does-shopify-take-per-salehttps://otum.io/blog/how-much-does-shopify-take-per-saleWhat Shopify really takes on each order, why it is more than your plan rate, and where to find the fee it actually charged.Thu, 24 Sep 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/reconcile-shopify-payout-to-ordershttps://otum.io/blog/reconcile-shopify-payout-to-ordersWhat a Shopify payout actually contains, and how to tie one back to the orders that produced it.Thu, 24 Sep 2026 00:00:00 GMTStavros Symeonidishttps://otum.io/blog/why-ai-projects-failhttps://otum.io/blog/why-ai-projects-failWhat actually makes AI projects fail, and the engineering that makes one stick.Mon, 13 Jul 2026 00:00:00 GMTStavros Symeonidis