Spreadsheets and data

Free CSV Merge Tool.

Merged table with unmatched and duplicate-key report.

Combine the tables you provide with explicit key and unmatched-row rules, keeping the merge understandable and reviewable.

Chrome extension + account required.
25 free automation tasks/month across tools. Browser-provider limits apply.

WHAT TO HAVE READY

CSV tables and join keys.

YOUR STARTING POINT

A task you can make yours.

Copy it here. Paste it into WebAct when you are ready.

This page prepares your prompt. The task runs in WebAct.

01

Make the task yours.

Review the prompt above. Add your goal and any requirements that matter.

02

Bring it to WebAct.

Open WebAct, paste the task and provide the data and rules. Review any proposed calculation or code action before approving it, then check a known example.

03

Check the useful part.

Check formulas, code and calculations against known inputs in the appropriate runtime. Review actions before execution and keep the original data available.

A PRACTICAL GUIDE

How to use the CSV Merge Tool.

Choose whether merging means appending rows or joining by a key. Specify how duplicate keys and unmatched records should be handled.

Make the workflow fit your task.

Choose append or join, define the key and select which side's unmatched records to keep. Inspect duplicate keys before combining tables. Show source labels for conflicting columns and reconcile the output count against the chosen merge relationship.

What you provide
CSV tables and join keys.
What you get
Merged table with unmatched and duplicate-key report.

See the input and the result.

Illustrative input and output · a teaching example, not a live WebAct run

Example input

Left join two CSV tables on id, with unique keys. Table A:
id,name
1,Ada
2,Sam
Table B:
id,status
1,Active
3,Inactive

Completed example

id,name,status
1,Ada,Active
2,Sam,

Reconciliation: two output rows. A key 2 has no B match. B key 3 is outside the left join and is reported separately. No duplicate keys in either input.
Download this example

Load this input into the prompt, then copy it to WebAct to try the task. Your result may differ from the illustration.

Decisions and troubleshooting.

What happens when both tables contain repeated join keys?

A many-to-many join can multiply rows. Decide whether that relationship is valid before merging or aggregating the inputs.

Why are some records missing after a CSV join?

An inner join excludes unmatched keys. Check whitespace, key types and whether a left or full join was intended.

Try it with your own source.

Replace the example with your material in the task prompt. Keep the requirements you need, then copy the task into WebAct.

Customize and copy the task ↑
BEFORE YOU BEGIN

Using WebAct.

The prompt and example are available here. Run your task in the WebAct Chrome extension.

Is this tool free?

You can copy and edit the prompt here for free. To use it with WebAct, install the Chrome extension, create and verify your account, and connect an available browser ChatGPT session. The Free plan includes 25 user-started automation tasks per calendar month, shared across tools. Ordinary browser Chat is separate; provider limits apply.

Learn about shared context in our privacy policy and choosing Chat or Task.

FROM A PROMPT TO YOUR OWN WORK

Bring the task to your page.

Install WebAct, add your source material and make the result yours.

Install WebAct