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. No password field.
The problem
When your FBA inventory doesn't match what you think you sent, Amazon hands you a number and nothing to check it against. 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: your ledger rebuilt for you, from files you already have, on data you can trace back to the source row.
How it works
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.
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.
Each FNSKU gets a reconciled balance, a variance against Amazon's own ending balance, and a status. The figures are assembled from rows in the files you uploaded, and you can open the rows behind them.
The ledger
Leviathan Recon reconstructs your unit ledger from the files you export yourself, following units through the events that move them in and out of Amazon's fulfilment network. What comes out is a balance per FNSKU, set against the balance Amazon reports for that same FNSKU — and the difference between the two.
Each figure is assembled from rows in the reports you uploaded, and the link back is kept: open a number and you land on the rows it was built from. When a variance looks wrong, you can check it yourself instead of asking us to explain it.
Each FNSKU then carries 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.
The 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.
Client account
Leviathan Recon
Leviathan Recon
Data span: Apr 2024 – Apr 2026
Shipment recon
Returns recon
Adjustment recon
Full inventory recon
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?
Where did your graded units finally land?
What did Amazon's inventory adjustments actually change?
The master per-FNSKU balance, against Amazon's.
Check our working
Fifteen raw tables holding the reports 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 — so a discrepancy has somewhere to live between spotting it and resolving it.
Shipped to FBA, FBA Received, Net Shortage, Sold, Returns, Reimbursed, In Stock, and Unrecovered — the whole flow on one screen, with the rows behind a figure a click away.
Security and data
Recon works from reports you export yourself. You upload the files, and it rebuilds your unit ledger from them.
Recon has no password field and nowhere to store one. A Seller Central login is not part of how it works, at signup or afterwards.
That is the whole of what it does. It cannot place orders, change listings, move funds, or act in your account.
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.