Deduptio vs a CSV export and a spreadsheet

Last checked September 1, 2026 · Deduptio is our product. Every claim about another tool comes from its public site or documentation and is linked in place — tell us if something is out of date.

Every Attio duplicate cleanup starts here, because it is free and it works for the first twenty minutes. Export the object, sort by email, add a COUNTIF, and there is your duplicate list. It is a genuinely good way to find out how bad the problem is.

The short version: a spreadsheet is a measuring tool, not a cleaning tool. It can tell you that 340 of your 6,000 people are duplicates. It cannot merge a single one of them, and the obvious next move — clean the file and re-import it — does not delete anything and quietly creates a second generation of duplicates.

Side by side

The re-import trap

This is the mistake worth spelling out, because it is the natural thing to try and it is the one that does damage.

Attio's CSV importer matches incoming rows against existing records using a unique attribute — typically email for people, domain for companies — and updates the record it matches, or creates a new one if it matches nothing. There is no third behaviour. It never deletes.

So when you re-import a cleaned file:

• The rows you deleted in the spreadsheet are simply not in the import. The records behind them are still sitting in Attio, untouched. Nothing was cleaned.
• Any row whose identifying value you tidied while cleaning — fixing a typo in an email, switching a company to its new domain — no longer matches the record it came from, so Attio creates a new record. You have added duplicates while trying to remove them.
• If you did not map a unique attribute at all, every row is new. One import can double an object. See duplicates from a CSV import for how that plays out and how to recover.

What the export does not contain

Finding a duplicate group is the easy half. Deciding which record survives is the half that matters, and it depends on information the CSV does not carry: how many emails and calls are attached to each record, which one other records reference, which lists each one sits in, which one your automations already use, and which one someone updated this morning. In a spreadsheet you are choosing a survivor from a name and a created date.

That is also why exports go stale. By the time a careful cleanup is finished, the workspace has moved on — new records created by email sync, by a form, by a teammate — and the file describes a workspace that no longer exists.

Where the spreadsheet is genuinely right

Before the import. A file that has not landed in Attio yet has no history, no relationships and no list memberships to protect, so collapsing duplicate rows in a spreadsheet is exactly the correct move — and cheaper than any tool. Clean the file, map a unique attribute so Attio matches rather than duplicates, and load companies before people so associations resolve.

After the import, the spreadsheet's job is measurement: how many duplicates, on which object, matching on what. That number is worth having before you decide whether this is a ten-minute job in the Attio UI or something that needs a tool.

Which should you use?

• Spreadsheet for pre-import cleanup, one-off analysis, and finding out how big the problem is.
• Attio's native mergeif the answer turns out to be "about a dozen". See Deduptio vs Attio's native merge.
• Deduptio when the count runs to hundreds, when the matching needs to be fuzzy or normalized, when the object is one Attio cannot merge by hand, or when you want the whole thing reversible.

Related

• Duplicates from a CSV import into Attio — preventing them at import time, and cleaning up after the one that got away.
• The Attio deduplication guide — rule design, survivor selection and verification.
• All comparisons · Tools that do not support Attio