Leviathan rebuilds your Amazon inventory ledger from your own reports — shipment by shipment, return by return, per FNSKU — then shows you exactly where Amazon's balance and yours stop agreeing.
No credit card. No API connection. We never ask for your Seller Central password.
The problem
When your FBA inventory doesn't match what you think you sent, Amazon hands you a number and no working. The reports that would explain it live in six different places, cover different date ranges, and don't share a common key — Amazon recommends reconciling by FNSKU, then ships you shipment reports that don't carry the FNSKU field.
So most sellers do one of three things. They export everything into a spreadsheet and lose a weekend. They pay a reimbursement tool that connects to their account and tells them what it thinks it can claim, without showing the ledger the claim came from. Or they let it go — and every discrepancy older than sixty days stops being recoverable, permanently.
Leviathan is the fourth option: the arithmetic, done for you, from files you already have, on data you can always trace back to the source row.
How it works
01
From Seller Central, the ordinary way. Sixteen report types are supported, and all but the settlement report have a downloadable template so you know exactly what we expect. Four are enough to begin: Shipped to FBA, Inventory Event Detail, Reimbursements, and Inbound Shipments.
02
Drag them in. Rows are checked against what you've already uploaded, so re-uploading last month's export doesn't double-count a single unit. You'll see how many rows were added and how many were skipped, every time.
03
Every FNSKU gets a reconciled balance, a variance against Amazon's own ending balance, and a status. Nothing is estimated. Every figure traces back to a row in a file you uploaded, and you can open that row.
The ledger
Most tools ask you to trust a black box. Here is ours, in full:
Your ending balance =
Variance =
Amazon's ending balance − your ending balance
Applied per FNSKU. Then every FNSKU is given a status:
Take Action is the number that matters. It's a specific quantity of a specific FNSKU that Amazon's own reports cannot explain — which is exactly what a reimbursement claim needs to be made of.
Nine modules
A single inventory number can't tell you whether a unit was lost inbound, damaged in a return, never received back from a removal, or quietly absorbed into an adjustment. Each one is a different question with a different paper trail.
Did FBA receive what you actually shipped?
Did your removal orders come back — complete, damaged, or not at all?
Did each customer return land back in sellable stock, or get reimbursed?
Was every replacement unit covered by a return or a reimbursement?
Do FC-to-FC transfers net to zero, or did units disappear in transit?
Receiving workspace for units routed into Grade & Resell.
Where did those Grade & Resell units finally end up?
What did Amazon's inventory adjustments actually change?
The master per-FNSKU balance, against Amazon's.
Check our working
Fifteen raw tables — every report you've uploaded, searchable and filterable, exportable to CSV. When a variance looks wrong, you don't file a support ticket. You open the rows and look.
Discrepancies become tracked cases, per module, with status, remarks and attachments. Nothing that needs action sits in someone's inbox.
Shipped to FBA, FBA Received, Net Shortage, Sold, Returns, Reimbursed, In Stock, and Unrecovered — the whole flow on one screen, each figure clicking through to the rows behind it.
Security and data
Leviathan has no technical path into your Amazon account, because one was never built. You export your reports and upload the files.
Not at signup, not during onboarding, not ever. If anyone asks you for it in our name, it isn't us.
There is nothing to misuse, because there is no access to misuse.
Every client gets a separate PostgreSQL database — not a shared table with your company name in a column. Your rows are not sitting alongside another seller's.
Give your team Admin, Vendor or Viewer access, adjust permissions per module per person, and see every change anyone made, when.
Every table exports to CSV. Findings from your trial are yours to keep, whether or not you continue.
Payment reconciliation — settlements, refunds and fee verification against your bank deposits — is in development. We built inventory first because everything downstream depends on the unit count being right.
FAQ
Verify your email, upload four reports, and see your own variance. A person on our team provisions your workspace and sends login details within one business day. No card at any point.