MasterMerge
Free for up to 5,000 rows

Combine every spreadsheet into one clean master list.

Drop in every export, every sign-up sheet, every old list. MasterMerge lines up the columns, finds the duplicates and keeps the most complete record of each person, with the gaps filled from the others.

Merge your first files free See how it works

Your files never leave your computer. No card needed.

Four steps, about a minute

  1. 1

    Drop in your spreadsheets

    CSV, Excel or both, as many as your plan allows. Nothing is uploaded: your browser does the work.

  2. 2

    Check the columns

    We match columns with different names ("E-mail", "Email Address") and you can fix any match.

  3. 3

    Choose how to spot duplicates

    By email, phone, name and company, or your own keys. The most complete record wins, gaps filled from the others.

  4. 4

    Download your master list

    CSV free, Excel and ready-made exports for HubSpot, Mailchimp and more on paid plans.

Private by design

The merge runs in your browser, on your computer. Customer lists never touch our servers unless you choose to save a result.

The best record wins

Duplicates are matched on email, phone, or name and company. The fullest record is kept and its empty cells are filled from the rest.

Big files, no waiting

Hundreds of thousands of rows in seconds. Every sheet of every Excel file, CSVs in any layout, columns lined up for you.

Combine spreadsheets in your browserCSV and Excel, every sheet, columns lined up by name. Your files never leave your computer.
Duplicate removal, most complete record winsMatch on email, phone or name and company. Keeps the fullest record and fills its gaps from the others.
Automatic column matching"E-mail", "Email Address" and "email" become one column. Fix any match by hand.
Clean-up rulesTrim spaces, fix capitals, tidy emails and phone numbers, drop empty rows.
Fuzzy matchingCatches "Jon Smith, Acme Inc" and "John Smith, ACME" as the same person.
Saved recipesSave mappings and rules once, run them on next month's files in one click.
Excel and JSON exportDownload as .xlsx (with a duplicates sheet) or JSON, not only CSV.
Field-by-field winner rulesPer column: newest file wins, longest value wins, or a source you trust most.
Ready-made exportsColumns named and ordered for HubSpot, Mailchimp, Salesforce, Google Contacts and Notion.
Split exportsOne file per value of a column (per state, per owner), or chunks of any size.
Saved results in the cloudKeep merged files online and download them again from any computer.
Built-in CRMContacts and a simple pipeline. Send any merge straight in, deduplicated against what is already there.
Capture formsA form to embed on any site. New entries land in the CRM, deduplicated.
API and integrationsAPI tokens for Zapier, Make, n8n and your own scripts.
Custom rolesChoose what each role can do, and make roles of your own.
Your own file storageKeep saved files in your own Cloudflare R2 or S3 bucket.

Simple pricing

Start free. Every paid plan starts with a 14-day trial of Pro. Cancel any time.

Free

Combine and deduplicate up to 3 files and 5,000 rows at a time.

$0 a month
  • 3 files per merge
  • 5,000 rows per merge
  • 1 members
  • Duplicate removal, most complete record wins
  • Clean-up rules
Start free

Starter

For one person cleaning lists every week.

$9.99 a month

or $99 a year

  • 25 files per merge
  • 250,000 rows per merge
  • 1 members
  • Duplicate removal, most complete record wins
  • Clean-up rules
  • Fuzzy matching
  • Saved recipes
  • Excel and JSON export
Try Starter

Pro

Most popular

Big files, exact control and exports for every tool.

$29.99 a month

or $299 a year

  • Unlimited files per merge
  • 2,000,000 rows per merge
  • 3 members
  • Duplicate removal, most complete record wins
  • Clean-up rules
  • Fuzzy matching
  • Saved recipes
  • Excel and JSON export
  • Field-by-field winner rules
  • Ready-made exports
  • Split exports
  • Saved results in the cloud
Try Pro

Business

Everything in Pro, plus a CRM and capture forms for the team.

$49 a month

or $490 a year

  • Unlimited files per merge
  • 2,000,000 rows per merge
  • 10 members
  • 25,000 CRM contacts
  • Duplicate removal, most complete record wins
  • Clean-up rules
  • Fuzzy matching
  • Saved recipes
  • Excel and JSON export
  • Field-by-field winner rules
  • Ready-made exports
  • Split exports
  • Saved results in the cloud
  • Built-in CRM
  • Capture forms
Try Business

Questions

Do you see my data?

No. Files are opened by your browser and merged on your computer. We store only what you would see in your history: file names, row counts and the settings you used. On Pro you can choose to save a result online.

Which files work?

CSV, TSV and Excel (xlsx, xls, xlsm, xlsb) plus OpenDocument spreadsheets. Every sheet of an Excel file comes in as its own source.

How big can a file be?

Free merges up to 5,000 rows, Starter 250,000 and Pro and Business up to two million. Very large files need a computer with enough memory; CSV uses less than Excel.

How are duplicates decided?

By the rules you pick: same email, same phone, or same name at the same company, plus fuzzy name matching on paid plans. You can see every group that was merged before you download.

Can I cancel?

Any time, from Plan and billing. You keep your plan until the end of the period, then move to Free. Nothing is deleted.

One clean list in a minute

Merge your first files free