migration-verify-demo — Verify data migrations by comparing source and target exports

A product-independent migration verification demo. It compares source and target CSV/JSON exports in a static browser page or standard-library Python CLI. It reports row and key differences, value mismatches, null ratios, type/format changes, attachment/reference integrity, fixed-length truncation, and consistent timezone shifts.

All fixtures are synthetic. They do not represent any client, CRM vendor, or production migration.

The measured run.

Both source and broken-target exports contain 300 rows. The broken target contains one explicit synthetic replacement key to preserve fixed row count while planting three missing source keys and two duplicate target rows.

The 25 findings are: three source-only keys, one target-only replacement key, two duplicate target rows, twelve absent attachment/reference values, five 50-character truncations, one mixed date-format signal, one consistent +9-hour timezone signal.

Honest limits.

The checker produces explicit evidence for a person to review. It does not decide whether a migration should be accepted. There is no server endpoint, upload, storage, cookie, analytics script, or external dependency. Files remain in browser memory. No pip install needed.

Code: https://www.twine.net/signin