Join Key Analyzer Online - Free Browser Tool

Delimiterdetected: ","

Two CSV tables separated by ===CSV

Best keyemail -> email

Best score83/100

Candidates8

Expected unmatched50.0% / 33.3%

candidate	score	matched	left only	right only	blank A/B
email -> email	83	2	2 (50.0%)	1 (33.3%)	0 / 0
id -> customer_id	71	2	2 (50.0%)	1 (33.3%)	0 / 0
id -> orders	71	2	2 (50.0%)	1 (33.3%)	0 / 0
id -> email	30	0	4 (100.0%)	3 (100.0%)	0 / 0
email -> customer_id	30	0	4 (100.0%)	3 (100.0%)	0 / 0
email -> orders	30	0	4 (100.0%)	3 (100.0%)	0 / 0
name -> customer_id	30	0	4 (100.0%)	3 (100.0%)	0 / 0
name -> email	30	0	4 (100.0%)	3 (100.0%)	0 / 0

Join key report CSVCSV

left_column,right_column,score,matched_distinct,left_only,right_only,left_unmatched_pct,right_unmatched_pct,duplicate_left,duplicate_right,blank_left,blank_right
email,email,83,2,2,1,50.00,33.33,0,0,0,0
id,customer_id,71,2,2,1,50.00,33.33,0,0,0,0
id,orders,71,2,2,1,50.00,33.33,0,0,0,0
id,email,30,0,4,3,100.00,100.00,0,0,0,0
email,customer_id,30,0,4,3,100.00,100.00,0,0,0,0
email,orders,30,0,4,3,100.00,100.00,0,0,0,0
name,customer_id,30,0,4,3,100.00,100.00,0,0,0,0
name,email,30,0,4,3,100.00,100.00,0,0,0,0

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

What is Join Key Analyzer?

Join Key Analyzer is a free, browser-based tool that helps you understand a dataset at a glance. Compare two CSV tables and rank the safest join keys with duplicate and unmatched-rate diagnostics. 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 Join Key Analyzer

1Paste your data or drop a file (CSV or JSON).
2Read the generated summary — types, counts, distributions, and any issues found.
3Export the report, or send the data to another tool to act on the findings.

Features

Per-column types, nulls, uniques, and stats
Spot data-quality issues fast
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

Profiling an unfamiliar dataset before analysis
Quick one-off analyzer 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 analysts
Researchers
Business analysts
Students
Analysts

Examples

Example 1

Example dataset

customer_id,email,revenue
1001,ava@example.com,89
1002,,249
1003,lee@example.com,129

Example insight

Rows: 3, columns: 3, missing email values: 1, numeric revenue column detected, no duplicate rows.

Example 2

Small dataset

A CSV or structured payload with a few rows

Quick summary

Row count, column count, detected types, and obvious issues.

Example 3

Dataset with missing values

Rows where one or more fields are blank

Completeness report

Missing counts and percentages show where review is needed.

Example 4

Dataset with numeric columns

Sales, revenue, score, duration, or other numeric fields

Numeric profile

Min, max, averages, spread, or outlier indicators where supported.

Example 5

Unknown export

A file from a system you have not inspected yet

First-pass diagnosis

The result helps decide whether to clean, validate, convert, or visualize next.

Common errors

A summary is treated as proof that the dataset is clean.
Outliers are removed automatically without checking whether they are real events.
Column types are trusted without reviewing mixed or sparse fields.
Duplicate or missing-value issues are ignored before visualization.

How it works

1Profiles the data input.
2Computes counts, inferred types, summaries, and warnings where supported.
3Turns findings into a practical next 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 Join Key Analyzer: analyze this dataset and summarize the main issues.

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
Profile the data first so missing values, types, duplicates, and outliers are visible before you edit it.
2
Run Join Key Analyzer
Review the preview, copy or download the result, and keep everything local in your browser.
3
Next recommended tool
Merge Datasets: Concatenate or join two tabular files.
Open tool
4
Then continue with
Primary Key Finder: Find unique identifiers, composite keys, and almost-keys that fail due to blanks or duplicates.
Open tool
5
Then continue with
Schema Mapper: Map source fields to a target schema with confidence scores.
Open tool

Frequently asked questions

How do I use Join Key Analyzer?: Paste or drop your data into the workspace, adjust the options to fit your data, then copy or download the result. Compare two CSV tables and rank the safest join keys with duplicate and unmatched-rate diagnostics.
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 Join Key Analyzer 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.
Do I need to install anything?: No installs and no extensions — it runs entirely in your web browser and even works offline once the page has loaded.

candidate

score

matched

left only

right only

dup A

dup B

blank A/B

email -> email

2 (50.0%)

1 (33.3%)

0 / 0

id -> customer_id

2 (50.0%)

1 (33.3%)

0 / 0

id -> orders

2 (50.0%)

1 (33.3%)

0 / 0

id -> email

4 (100.0%)

3 (100.0%)

0 / 0

email -> customer_id

4 (100.0%)

3 (100.0%)

0 / 0

email -> orders

4 (100.0%)

3 (100.0%)

0 / 0

name -> customer_id

4 (100.0%)

3 (100.0%)

0 / 0

name -> email

4 (100.0%)

3 (100.0%)

0 / 0

What is Join Key Analyzer?

Examples

Example 1

Example dataset

customer_id,email,revenue
1001,ava@example.com,89
1002,,249
1003,lee@example.com,129

Example insight

Rows: 3, columns: 3, missing email values: 1, numeric revenue column detected, no duplicate rows.

Example 2

Small dataset

A CSV or structured payload with a few rows

Quick summary

Row count, column count, detected types, and obvious issues.

Example 3

Dataset with missing values

Rows where one or more fields are blank

Completeness report

Missing counts and percentages show where review is needed.

Example 4

Dataset with numeric columns

Sales, revenue, score, duration, or other numeric fields

Numeric profile

Min, max, averages, spread, or outlier indicators where supported.

Example 5

Unknown export

A file from a system you have not inspected yet

First-pass diagnosis

The result helps decide whether to clean, validate, convert, or visualize next.

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 Join Key Analyzer: analyze this dataset and summarize the main issues.

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

Profile the data first so missing values, types, duplicates, and outliers are visible before you edit it.

Run Join Key Analyzer

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

Next recommended tool

Merge Datasets: Concatenate or join two tabular files.

Open tool

Then continue with

Primary Key Finder: Find unique identifiers, composite keys, and almost-keys that fail due to blanks or duplicates.

Open tool

Then continue with

Schema Mapper: Map source fields to a target schema with confidence scores.

Open tool

Frequently asked questions

How do I use Join Key Analyzer?

Paste or drop your data into the workspace, adjust the options to fit your data, then copy or download the result. Compare two CSV tables and rank the safest join keys with duplicate and unmatched-rate diagnostics.

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 Join Key Analyzer 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.

Do I need to install anything?

No installs and no extensions — it runs entirely in your web browser and even works offline once the page has loaded.