Data Contract Tester Validator Online

Delimiterdetected: ","

Contract CSV, then ===, then dataset CSVCSV

StatusFAIL

Rules4

Failures5

Columns tested4

row	column	rule	value	message
4	id	unique	2	Duplicate value first seen on row 3.
3	email	type	not-an-email	Expected email.
4	email	required		Required value is blank.
3	age	max	200	Expected <= 120.
4	status	regex	unknown	Does not match ^(active\|pending\|paused)$.

Contract test report CSVCSV

row,column,rule,value,message
4,id,unique,2,Duplicate value first seen on row 3.
3,email,type,not-an-email,Expected email.
4,email,required,,Required value is blank.
3,age,max,200,Expected <= 120.
4,status,regex,unknown,Does not match ^(active|pending|paused)$.

Tip: use samples, upload, copy, download, and send-to actions inside the workspace where available.

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.

How to use Data Contract Tester

1Paste your data or drop a file into the editor.
2The tool checks it instantly and flags any errors with the exact line and a plain-English message.
3Fix the highlighted issues and re-check until the input is valid.

Features

Pinpoints errors by line with clear messages
Validates as you type
100% client-side — no upload, fully private
Free with no account, no watermark, and no daily limit
Works on large inputs, limited only by your device's memory
Load a sample, then copy, download, or share your result

Common uses

Prototyping a data pipeline with no code
Quick one-off validator jobs without opening a heavy app
Preparing data before importing it elsewhere
Sharing a reproducible result with a teammate via a link

Used by

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

Examples

Example 1

Example input

Paste a value, document, or data file that may contain syntax or structure errors.

Example result

The validator lists each issue with a plain-language message and the location when available.

Example 2

Missing delimiter or quote

A value with an opening quote, bracket, or delimiter that is not closed

Validation message

The tool points to the first location where the structure becomes invalid.

Example 3

Unexpected trailing character

A valid-looking value followed by an extra comma, bracket, or token

Validation message

The extra character is flagged so you can remove it and re-check.

Example 4

Wrong value type

A field that should be numeric, boolean, URL, or structured data but is plain text

Validation warning

The result explains the mismatch where the tool can detect it.

Example 5

Clean input

A correctly structured value or file

Valid result

The validator confirms the input is ready for the next workflow step.

Common errors

A trailing comma appears after the last item.
A quote, bracket, parenthesis, or tag is opened but never closed.
A value has the right shape visually but the wrong type or encoding.
Copied input includes hidden characters from a document, terminal, or web page.

How it works

1Parses the data input locally.
2Checks structure and expected syntax.
3Reports the first issues clearly so they can be fixed.

AI prompt for this task

Use this prompt when you want an AI assistant to explain or double-check the same job.

Act as a data assistant. Use the same goal as Data Contract Tester Validator: find and explain every validation error.

Input:
[paste your data here]

Return the result, a short explanation, and any warnings about malformed, missing, duplicate, or sensitive values.

Recommended workflow

1
Prepare the input
Validate the raw input first so syntax or structure errors are caught before downstream tools touch it.
2
Run Data Contract Tester
Review the preview, copy or download the result, and keep everything local in your browser.
3
Next recommended tool
Data Validation Pipeline: Chain validators on a dataset and surface row-level failures.
Open tool
4
Then continue with
Dataset Health Analyzer: Score CSV health across missing values, duplicates, row shape, and type consistency.
Open tool
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.

row

column

rule

value

message

unique

Duplicate value first seen on row 3.

type

not-an-email

Expected email.

required

Required value is blank.

age

max

200

Expected <= 120.

status

regex

unknown

Does not match ^(active|pending|paused)$.

What is Data Contract Tester?

Examples

Example 1

Example input

Paste a value, document, or data file that may contain syntax or structure errors.

Example result

The validator lists each issue with a plain-language message and the location when available.

Example 2

Missing delimiter or quote

A value with an opening quote, bracket, or delimiter that is not closed

Validation message

The tool points to the first location where the structure becomes invalid.

Example 3

Unexpected trailing character

A valid-looking value followed by an extra comma, bracket, or token

Validation message

The extra character is flagged so you can remove it and re-check.

Example 4

Wrong value type

A field that should be numeric, boolean, URL, or structured data but is plain text

Validation warning

The result explains the mismatch where the tool can detect it.

Example 5

Clean input

A correctly structured value or file

Valid result

The validator confirms the input is ready for the next workflow step.

AI prompt for this task

Use this prompt when you want an AI assistant to explain or double-check the same job.

Act as a data assistant. Use the same goal as Data Contract Tester Validator: find and explain every validation error.

Input:
[paste your data here]

Return the result, a short explanation, and any warnings about malformed, missing, duplicate, or sensitive values.

Recommended workflow

Prepare the input

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

Run Data Contract Tester

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

Next recommended tool

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

Open tool

Then continue with

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

Open tool

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.