Validate schema and data rules before you share — catch missing fields, type issues, ranges, duplicates, and regex problems. Runs locally in your browser.
Upload
CSV / TSV / Excel (XLSX/XLS) / delimiter-style TXT
File: not loaded
Delimiter
Auto-detect
Comma (,)
Tab (TSV)
Semicolon (;)
Pipe (|)
Preview rows
25
50
100
Max invalid rows export
100
250
500
1000
Safety: your file is read locally in your browser. Use Masker if you need to share samples.
Privacy: processed locally in your browser. Nothing is uploaded unless you choose to share details for help.
Validation summary
What passed, what failed
Rows: —
Cols: —
Rules: 0
Invalid rows: 0
Total errors: 0
Upload a file to get a clear pass/fail decision you can rely on.
Validate
Download invalid rows CSV
Download report
Download schema JSON
Tip: Add a Unique rule on your primary key (like id ) to catch duplicates quickly.
1) Build rules
Add checks column-by-column
Rule
Required (not blank)
Type check
Numeric range
Text length
Regex pattern
Allowed values (enum)
Unique (no duplicates)
Date parse
Non-null if (conditional)
Add
Auto rules
Clear rules
Auto rules will add: Required for “id-like” columns, Type=number for numeric-looking columns, and Date parse if it sees date-like strings.
2) Rules list
Edit by deleting and re-adding
Active 0
Load a file to build rules.
3) Audit
Schema + thresholds + counts
Load a file, add rules, then click Validate.
Download the Report to keep a permanent record of checks run (useful for QA sign-off).
Preview
Rows with error details (top findings)
View
Invalid rows only
All rows (sample)
How to read results
Error breaks the schema (row should be rejected).
Warn might be acceptable, but should be reviewed.
Each failing row gets:
_errors : count of error-level issues_warns : count of warning-level issues_issues : human-readable list of what failed