# What happens when you merge in Dedupely for CSV | Dedupely > What a Dedupely merge does to a CSV file: file limits, combining files, rules for which value wins, previews and the clean file you export. - URL: https://dedupe.ly/blog/dedupely-insights/merge-in-dedupely-for-csv - Section: blog - Published: 2025-06-13 - Site index: https://dedupe.ly/llms.txt - Any page: append `.md` to its URL for this plain-text form --- Skip to content [New Dedupely Intelligence Now on every paid plan, monthly or yearly.](https://dedupe.ly/ai-deduplication) [Blog](https://dedupe.ly/blog) [Dedupely Insights](https://dedupe.ly/blog/dedupely-insights) ## What happens when you merge in Dedupely for CSV By [Gaby Salinas](https://www.linkedin.com/in/gbyslns) Updated October 28, 2026 # min read TL;DR - A spreadsheet is cleaned as a CSV file with a header row. - Several CSV files can be combined into one list when their headers match exactly. - Spreadsheet merges change only the spreadsheet, never the records in a connected CRM. - Spreadsheet rows don't count toward the plan's record limit. - Dedupely matches, merges and exports CSV files with the same rules and previews used for CRMs. Not every duplicate lives in a CRM yet. Event lists, webinar sign-ups, purchased lists and exports from other tools often arrive as spreadsheets, and they carry their own duplicates. Dedupely treats a spreadsheet as its seventh integration, next to HubSpot, Salesforce, Pipedrive, Close, Nimble and Google Contacts. You find and merge duplicates in a CSV file the way you would in a CRM, then download the clean file. In this post, you'll see what happens when you merge spreadsheets in Dedupely. That covers the files it takes, how merges work and what you get back. For spreadsheet apps and other ways to clean a file, see our roundup of [tools to clean a CSV before a CRM import](https://dedupe.ly/blog/productivity/tools-to-clean-csv-before-crm-import). ### What Dedupely takes as a spreadsheet Dedupely works with CSV files. If your list is in another spreadsheet format, save it as a CSV first. Each file needs a header row, since the headers become the fields you match and merge on. No CRM is needed. A spreadsheet gets its own workspace in Dedupely, separate from any CRM you connect. #### File limits | Limit | Maximum | | --- | --- | | Total upload size | 100 MB | | Files per upload | 10 | | Rows | 1,000,000 | | Columns | 50 | | Characters per cell | 350 | | Values per multi-value field | 175 | | Characters per field name | 100 | | Size per line | 4 MB | ### Combining several files into one list You can keep each file as its own spreadsheet workspace, or combine several files into one. Combining is how you find the person who appears in this month's event list and last month's webinar list. Files combine only when their headers are spelled exactly the same. Dedupely doesn't map one column name to another, so "Email" and "E-mail" stay separate fields. Rename the headers before you upload. Lining up the files is most of the work. Our post on [finding duplicates across several spreadsheets](https://dedupe.ly/blog/productivity/find-duplicates-across-spreadsheets) covers headers, formats and source columns. ### Matching works the same as in a CRM Once a file is in, you build duplicate searches on its columns the way you would on CRM fields. Each field gets its own match option: Exact, Similar for typos, Fuzzy for names that sound alike, Similar Words, Domain Root, or None. Filters narrow which rows a search looks at, and every search shows the number of matches and the records in them. What counts as a duplicate is still case by case. An attendee list may treat two people at one company as separate, while a mailing list may not. Columns import as text. In the spreadsheet's field settings, you can change a field's type and set it as multi-value, which lets merges append its values. ### What happens when rows merge A merge combines the rows in a duplicate set into one row. The values that survive come from your rules for which value wins, the same Merge Rules you'd use for a CRM. - **The surviving row:** choose the one with the most data, or a custom choice. - **Each field:** keep the surviving row's value, or set your own win and lose rules. - **Multi-value fields:** append values from every row, so no email or phone is dropped. Before you merge, you can preview each set, with the winning values in bold and the full result in the Preview Merge panel. #### Merges stay in Dedupely Spreadsheet merges change the spreadsheet workspace and nothing else. They never change records in a CRM, even one connected to the same Dedupely account. The file you uploaded stays as it was on your computer. That makes a spreadsheet a safe place to try merge logic. Our post on [testing merge logic with CSVs](https://dedupe.ly/blog/productivity/testing-merge-logic-with-csvs) covers how teams use it. ### Exporting the clean file When the merges are done, you create an export and download the clean records as a CSV. Each export is listed in the spreadsheet's Export History. You can also upload more files to the same workspace and keep merging. When you no longer need it, removing the spreadsheet workspace permanently deletes it and its data from Dedupely. ### Spreadsheets and your record limit Spreadsheet rows don't count toward your record limit. Only records synced from connected CRMs count. CSV uploads are unlimited on every plan and during the trial, so a one-off list never pushes you into a bigger plan. During the free trial, spreadsheet merges count toward the 20 free merges, the same as merges in a CRM. ### From a clean file to a clean CRM A clean spreadsheet has no duplicates inside it. It can still hold people who are already in your CRM. To catch those, import the clean file into your CRM and let Dedupely find duplicates against your existing records there. Connect the CRM itself to Dedupely for that step, so its records sync and merges happen directly in the CRM. Keep spreadsheet workspaces for lists that come from outside your CRM. Example Some teams get webinar and event leads in a spreadsheet, and some of those people are already in the CRM. Checking the list by hand before every upload takes a lot of work. ### How Dedupely helps you clean a spreadsheet In Dedupely, you upload CSV files, combine the ones with the same headers and build duplicate searches on their columns. You set rules for which value wins, preview each merge and download the clean file. [Clean your next spreadsheet](https://v2.app.dedupe.ly/signup) ### A clean list before it reaches the CRM Merging in a spreadsheet works like merging in a CRM, with one difference: nothing outside the file changes. You match on the columns you trust, decide which values win, preview the result and download a clean CSV. That makes spreadsheets the right place for lists that haven't reached your CRM yet. Every duplicate you merge in the file is one you won't have to merge in the CRM later. ### Frequently asked questions #### How do I merge duplicate rows in a CSV file? Pick the columns that decide a match, like email or company domain, and group rows that agree on them. Then decide which value wins in each other column, so the merged row keeps the best data. Preview a few merged rows before merging the rest, and keep the original file. #### Can I combine CSV files with different headers? Not directly in Dedupely, since files combine only when their headers are spelled exactly the same. Rename the columns in each file first, so the same field has the same header everywhere. Then upload them together and find the duplicates across the combined list. #### Does merging a spreadsheet in Dedupely change my CRM? No. Spreadsheet merges stay in Dedupely's spreadsheet workspace and never change records in a CRM, even one connected to the same account. To bring the clean list into your CRM, export it, import it, and let Dedupely find duplicates against your existing CRM records there. #### How large can a CSV file be in Dedupely? Up to 100 MB in total per upload, with up to 10 files at a time. A spreadsheet can hold up to 1,000,000 rows and 50 columns, with up to 350 characters per cell. Files over those limits need to be split, or trimmed to the columns you need. #### Do spreadsheets count toward Dedupely's record limit? No, only records synced from connected CRMs count toward the record limit. CSV uploads are unlimited on every plan and during the trial. Cleaning a large one-off list doesn't change the plan you need for your CRM records, however many rows it has. Behind the article ### Gaby Salinas Marketing Assistant at Dedupely Gaby Salinas came to CRM data from marketing and advertising, so she looks at duplicates from two sides: the match and merge logic behind them, and what they do to the people using the CRM, like the rep who calls a customer twice, the admin who gets blamed and the cleanup nobody wants to start. As Marketing Assistant at Dedupely, she follows how RevOps teams, end users, consultants and technical teams actually work with their data: the records they stop trusting, the workarounds they build and the moment they finally decide to clean up. What she finds shapes most of what Dedupely publishes. [Connect with Gaby on LinkedIn](https://www.linkedin.com/in/gbyslns) ### Contact us We’d be happy to help you get this set up. #### Write us a message We probably know the answer to your question already help@dedupe.ly Email copied to your clipboard! [Book a Zoom Whether you’re getting started or getting intense. Get in touch! Book a zoom](https://meetings.dedupe.ly/meetings/gaby-salinas/dedupely-zoom-scheduler) ### Discover Related Blog Posts Stay updated with our latest articles and insights. - [Productivity Testing merge logic with CSVs Use Dedupely’s CSV upload to test merge logic before syncing. It lets you compare records, refine match settings, and validate results, without risking changes. Clinton Skakun June 6, 2025](https://dedupe.ly/blog/productivity/testing-merge-logic-with-csvs) - [Productivity How to find duplicates across multiple spreadsheets To find duplicates across several spreadsheets, line up the headers, combine the files into one list, then match and merge before you import. Gaby Salinas October 19, 2026](https://dedupe.ly/blog/productivity/find-duplicates-across-spreadsheets) - [Productivity Best tools to clean a CSV before a CRM import Spreadsheet apps, scripts and data-prep apps can clean a CSV before a CRM import. See what each one finds, what it deletes and where it stops. Gaby Salinas October 28, 2026](https://dedupe.ly/blog/productivity/tools-to-clean-csv-before-crm-import) ### Get started for free 20 free trial merges and as much free support as you need to get your duplicates under control. [Try for free](https://v2.app.dedupe.ly/signup)[Talk to sales](https://meetings.dedupe.ly/meetings/gaby-salinas/talk-to-sales) [Or sign up with Google](https://v2.app.dedupe.ly/signup/google) Running CRM cleanup for clients? [See the Partner Program](https://dedupe.ly/become-a-partner)