Schema Validator
Validate a CSV file against a JSON or YAML schema definition. Fast, private, and secure browser-based tool with no signups or
Your files never leave your device. Processed locally. 100% private.
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How To Use Schema Validator
Complete your task perfectly in just three straightforward steps.
Upload CSV
Drop your CSV file.
Upload or define schema
Upload a JSON Schema or define rules manually: required columns, types, constraints.
Review results
Validation errors listed with row and column references. Download report.
Review Report
Instantly see missing columns, type violations, and unique constraint errors.
FAQ
Everything you need to know about the Schema Validator.
What schema formats are supported?
JSON Schema (draft-07) and custom YAML rule files.
Can I validate multiple CSVs?
Yes — run the same schema against multiple files and get one combined report.
Is my file uploaded?
No. Everything runs locally in your browser.
File size limit?
Process files up to the browser memory limit.
Can I save the schema?
Yes — export the schema for reuse in CI/CD pipelines or future validations.
Can I manually create a data contract JSON?
Yes. The contract is a simple JSON file with a 'name' field and a 'columns' array. Each column object needs at minimum 'name' (string) and 'type' (one of: 'string', 'integer', 'float', 'boolean', 'date'). Add 'nullable: false' to enforce NOT NULL. Example: {"name": "Orders Contract", "columns": [{"name": "order_id", "type": "integer", "nullable": false}, {"name": "customer_email", "type": "string"}]}
How many violations will it report?
The validator reports up to 500 row-level violations per run to keep the output readable. If your file has more than 500 violations, fix the systematic issue (wrong type in an entire column) and re-run. Missing column violations are always fully reported regardless of count.
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