# Remove Duplicates

> Keep each entry in a list only once.

The **Remove duplicates** step returns a list with repeats taken out. You say what makes two entries the same, and it keeps one of each.

> Dock: Data · Lists · Takes: a list · Returns: the list with repeats removed

Use it after combining sources that overlap. The same customer exported from two systems, an address on several orders, a lead that came in twice.

> **Deduplicating inside a single field?** You can remove duplicates directly inside field tokens using [Data Transformation](/build/core-concepts/data-transformation) with `{{ 2.emails | remove_duplicates }}` (or `{{ 2.records | pluck:email | remove_duplicates }}`). Use this dedicated **Remove duplicates** step when deduplicating complex multi-field records or processing large datasets (up to 100,000 items).

## Setting it up

### Choose the list

Pick it from the lists the field offers, which come from the steps before this one. Choose **Enter it myself** to type a reference such as `{{ 3.results }}` or paste a JSON list instead.

### Say what makes two entries the same

For a list of plain values, the value itself. For a list of records, name the field, such as `email` or `customer_id`.

### Choose which copy to keep

The first one seen, or the last.

## Which copy you keep changes the data, not the order

**The surviving items stay in the order they first appeared**, whichever copy wins. Keeping the last one does not reverse anything.

What changes is _which_ record survives, and with real data that matters. Say a customer appears twice, once with an old address and once with a new one. **First** keeps the old, **Last** keeps the new, assuming the newer record came later in the list.

For a list of plain values it makes no difference at all: the same value is the same value.

## Capital letters count unless you say otherwise

**Ignore capitalisation** is off to begin with, so `Active` and `active` are two different values and both survive.

Turn it on when the same thing is spelled differently by two systems: one exports upper case, the other lower.

## What it passes on

The list with repeats removed:

```
{{ 5.$full_result }}
```

Shorter than the input, or the same length when nothing repeated.

The step also counts the items for you: `{{ 5.resultCount }}` is how many it passed on, and `{{ 5.results }}` is the list as the data panel offers it.

## Examples to copy

### One email per person

Two exports combined into one list, some people in both.

- **Field**: `email`
- **Keep**: Last
- **Ignore capitalisation**: on

_Last_ is the choice when the second export is the more recent one and its values should win. Ignoring capitalisation catches `Anna@example.com` and `anna@example.com` as one person.

### Unique tags

A list of plain text values with repeats.

- **Field**: leave empty, so the value itself is compared
- **Keep**: First

## Limits

Remove duplicates works on lists of up to 100,000 items. A longer list is refused with a message naming both numbers.

## What's Next?

- [Combine](/build/action-steps/combine) — merge two lists before removing repeats
- [Sort](/build/action-steps/sort) — decide which copy counts as first
- [Summarize](/build/action-steps/summarize) — count what is left