FBA Gap Auditor
Amazon's own reports go in; a worklist of gaps comes out, each with the time left to file.
A full worklist of gaps with a countdown on each, for the first 200 reimbursement rows.
$5 a month on its own, or in Documents ($12 a month); every paid tool for $24. It adds: Claim templates, calendar export and unlimited rows.
One subscription, one invoice — add a tool any time, prorated. Sign in and it unlocks; or paste your key once per device.
Email support@avyth.com and the person who built FBA Gap Auditor reads it. If it fails on your file, say what the file looks like — that is usually enough to fix it.