---
title: What is a data clean room? · EleeN
url: https://www.eleenai.com/en/resources/what-is-a-data-clean-room
language: en
description: What a data clean room is, how two organisations use one to answer shared questions without seeing each other's records, and when to use one.
---

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3. What is a data clean room?

# What is a data clean room?

ExplainerPublished 24 October 2026

A data clean room is a secure environment where two or more organisations analyse their combined data without either side seeing the other's records. Only aggregate answers come out, such as how many customers they share.

## In this article

1. [01Why clean rooms exist](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#why)
2. [02How a clean room works](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#how)
3. [03What teams use clean rooms for](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#uses)
4. [04What a clean room doesn't do](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#limits)
5. [05Questions to ask when choosing one](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#choose)
6. [06How EleeN approaches clean rooms](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#eleen)

In this article

1. [01Why clean rooms exist](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#why)
2. [02How a clean room works](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#how)
3. [03What teams use clean rooms for](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#uses)
4. [04What a clean room doesn't do](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#limits)
5. [05Questions to ask when choosing one](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#choose)
6. [06How EleeN approaches clean rooms](https://www.eleenai.com/en/resources/what-is-a-data-clean-room#eleen)

## 01Why clean rooms exist

Companies often learn more together than apart. A bank and a retailer may want to know how many customers they share; a brand may want to know whether a campaign on a publisher's site changed what people bought.

The traditional way to answer those questions was to exchange customer lists. That leaves copies of personal data in other companies' systems, often without a clear record of consent or purpose, which privacy laws such as Saudi Arabia's [Personal Data Protection Law](https://www.eleenai.com/en/resources/pdpl-and-data-collaboration) make harder to justify.

At the same time, browsers and phones now limit third-party cookies and mobile ad IDs, so companies rely more on their own first-party data, and on their partners', to reach and measure customers. Clean rooms let them work together on that data safely.

## 02How a clean room works

The details vary between providers, but most clean rooms follow the same pattern:

- Each side connects its data: ideally read where it already lives, rather than copied into a shared database.
- Identifiers are pseudonymised: emails and phone numbers are hashed, a one-way scrambling that lets records be matched without being read.
- The questions are agreed: partners decide in advance what can be asked, such as overlap or reach.
- Privacy rules are applied: results come back only as aggregates, and groups too small to hide individuals are held back.
- Everything is recorded: an audit trail shows who asked what, and when.

## 03What teams use clean rooms for

- Overlap analysis: how many customers two companies share, and how those customers break down.
- Audience building: combining both sides' signals to define a segment neither could build alone, then activating it on ad platforms.
- Measurement: matching who saw a campaign with who bought, to see what it changed (the lift).
- Planning: sizing audiences and reach before committing a budget.

## 04What a clean room doesn't do

A clean room reduces risk; it doesn't remove responsibility. A few things to keep in mind:

- Hashing is pseudonymisation, not anonymisation: hashed identifiers can still relate to real people, so they deserve the same care as the original data.
- You still need a lawful basis: a clean room doesn't replace consent, or another basis, for using the data in the first place.
- Results depend on matching: if identifiers don't resolve well, overlaps look smaller than they are.
- It isn't a warehouse or a CDP: a clean room answers shared questions; it doesn't replace the systems where you store and manage customer data.

## 05Questions to ask when choosing one

- Does the data stay where it lives, or is it copied to the provider?
- Which privacy rules can partners set, and can either side weaken them later?
- Are results below the minimum group size dropped silently, or counted so you know?
- How well does it match identifiers in your market?
- Can results become audiences, and how do they reach ad platforms?
- Is there a complete audit trail you can export?
- What does it cost the partner you invite?

## 06How EleeN approaches clean rooms

In EleeN, a clean room is a collaboration with one partner. Each side's data is read in place and matched as hashed EleeNIDs, and only aggregate answers come out. Privacy terms bind both sides and can only be tightened, every result counts the groups it held back, and the side that starts a collaboration pays, so partners join free. [See how EleeN clean rooms work](https://www.eleenai.com/en/platform/clean-rooms).

Keep reading

## Go further. Related pages and explainers.

[Clean roomsSet up a clean room with one partner, agree the questions up front, and get aggregate answers like overlap and reach. Each side keeps its own records.](https://www.eleenai.com/en/platform/clean-rooms) · [What is identity resolution?What identity resolution is, how emails, phone numbers and device IDs resolve into one ID per person, and why it matters for data collaboration.](https://www.eleenai.com/en/resources/what-is-identity-resolution) · [GovernanceSet roles, a minimum group size every collaboration starts from, approvals for what goes out, and a full audit trail, the way the PDPL expects.](https://www.eleenai.com/en/platform/governance)

Get started

## See a clean room answer your own question. One collaboration, start to finish, on a call.

Tell us the partner and the question you have in mind, and we'll show how the room would answer it.

[Book a call](https://www.eleenai.com/en/contact) · [How clean rooms work](https://www.eleenai.com/en/platform/clean-rooms)

What happens next

1. [01]A call about your data and goals
2. [02]Your team connects one source
3. [03]Start with an audience, the marketplace or a partner

Try it

Pick a partner

A brandA retailerA publisher

- Only yours
- Shared
- Only theirs

288,000

Shared customers

Example figures only.

## [Platform](https://www.eleenai.com/en/platform)

- [EleeNID](https://www.eleenai.com/en/platform/identity)
- [Clean rooms](https://www.eleenai.com/en/platform/clean-rooms)
- [Marketplace](https://www.eleenai.com/en/platform/marketplace)
- [Activation](https://www.eleenai.com/en/platform/activation)
- [Governance](https://www.eleenai.com/en/platform/governance)
- [Integrations](https://www.eleenai.com/en/platform/integrations)

## [Solutions](https://www.eleenai.com/en/solutions)

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- [Media](https://www.eleenai.com/en/solutions/media)
- [Healthcare](https://www.eleenai.com/en/solutions/healthcare)
- [Data providers](https://www.eleenai.com/en/data-providers)

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