FileSpecGuardCONTROL THE HANDOFF
Make each change
an explicit decision.
Approve a reusable column mapping. Inspect the transformed preview. Compare two declared schemas before your next handoff.
01 / APPROVED MAPPING
From supplier columns to your target.
Rename, reorder or drop columns, with optional trim and case operations. Numeric strings remain strings: no currency conversion, rounding, arithmetic or automatic type inference.
Read your source
Maximum 1 MiB, 10,000 data rows and 100 columns. Exact header case and spaces matter. Quoted fields are supported. XLSX is not supported. Files are read only when you choose the read action.
Read a source to define its mapping.
Review the exact mapping
Keep string for identifiers with leading zeros. Decimal accepts up to 100 whole digits and 18 decimal places without rounding; integer accepts a sign and digits; boolean requires true or false; date requires a valid YYYY-MM-DD. Nullable permits an empty string only. Case operations use JavaScript Unicode casing; review changed values.
| Include | Source | Target | Operation | Target type | Nullable | Order |
|---|
A mapping file contains column names and rules, never the source rows. Import requires the exact same source header order and delimiter. Imported definitions need fresh approval. Revision numbers are your local labels, not a shared publication or audit system.
Transformed preview
First five source and output records. Full output is validated. Original content appears only on this device. A target-validation pass covers the declared cell types and required values, not business accuracy, malware or downstream compatibility.
Validation findings
Export deliberately
Lossless JSON preserves exact strings, leading zeros and decimal precision. Spreadsheet-safe CSV quotes every cell and prefixes potentially active cells with an apostrophe, including signed numeric strings; spreadsheet applications may also infer types. Review that export policy before loading into another system. No output is labeled import-ready.
02 / SCHEMAWATCH COMPARISON
Review the changes between two snapshots.
Supply two explicit declarations. This comparison identifies added, removed, type, nullability and relative-order changes. It does not query a source, infer a schema, monitor a schedule or send alerts.
JSON format: version 1 and a fields array. Each field contains name, type and nullable. Types: string, integer, decimal, boolean, date. Maximum 100 fields and 125 KiB per snapshot. Names are exact literal field paths; renames appear as removal plus addition.
Enter both snapshots or load the synthetic example to see the format.
Changes for review
| Field | Change | Before | After | Review |
|---|
Removal has high review priority; all other detected changes need review. Priority is not a compatibility verdict. Unchanged declarations do not prove unchanged data or safe downstream behavior.
Keep the specification useful.
For recurring handoffs, agree ownership, allowed values and a measured acceptance process. Discuss a scoped specification review; no file is attached to this link.
All work here stays in browser memory until you export it. Leaving or reloading can lose your work. Clear removes the current in-memory workspace; it does not delete original files or exports and is not secure erasure.