Data Contract Tester

What is Data Contract Tester?

Data Contract Tester Validator is a free, browser-based tool that helps you catch errors before they reach production. Validate CSV datasets against required fields, types, uniqueness, ranges, and regex rules. It's built for speed and privacy: Everything runs locally in your browser — your data is never uploaded to a server. No sign-up, no installs, and no daily limits.

Used by

• Data engineers
• Analytics engineers
• Database administrators
• Operations teams
• QA engineers
• API testers

Recommended workflow

1. 1

   Prepare the input

   Validate the raw input first so syntax or structure errors are caught before downstream tools touch it.

2. 2

   Run Data Contract Tester

   Review the preview, copy or download the result, and keep everything local in your browser.

3. 3

   Next recommended tool

   Data Validation Pipeline: Chain validators on a dataset and surface row-level failures.

   Open tool
4. 4

   Then continue with

   Dataset Health Analyzer: Score CSV health across missing values, duplicates, row shape, and type consistency.

   Open tool
5. 5

   Then continue with

   Schema Drift Detector: Compare two CSV or JSON samples for added, removed, renamed, type, nullability, and enum drift.

   Open tool

Frequently asked questions

How do I use Data Contract Tester?

Paste or drop your data into the workspace, adjust the options to fit your data, then copy or download the result. Validate CSV datasets against required fields, types, uniqueness, ranges, and regex rules.

Is my data uploaded or stored anywhere?

No. Everything runs locally in your browser — your data is never uploaded to a server. Nothing is sent to a server, so it's safe to use with private or sensitive data.

Is Data Contract Tester Validator free?

Yes — it's completely free with no account, no sign-up, no watermark, and no daily usage limits.

What's the maximum file size?

There's no hard limit imposed by the tool. Because processing happens in your browser, the practical ceiling is your device's available memory — most everyday files work instantly.

Does it explain the errors it finds?

Yes — each problem is reported with the line number and a plain-English description so you can fix it quickly.