IAB Tech Lab has finalized guidelines for sending Event and Conversion API (ECAPI) events to data clean rooms, and says implementers can start using them now.
What IAB Tech Lab published
The Tech Lab announced the finalized guidelines in a post on November 3 written by Jill Wittkopp, VP of Product at IAB Tech Lab. The ECAPI Working Group developed them so that collaborators in a clean room share a common object format and data schema for conversion events. They had been open for public comment until September 4, 2026.
The guidelines cover data moving between systems. They do not cover how a clean room stores or processes the data once it arrives. They are written around Parquet, a file format the Tech Lab calls “an accepted standard for this method.” Other ways of providing ECAPI events to a clean room, which the post lists as live tables, governed shares, catalog references, streams and APIs, “may have different requirements and are not covered.”
Where ECAPI comes from
The core ECAPI standard was finalized in April 2026. It standardizes how advertisers send marketing events to platforms and partners from their own servers, so that recipients can optimize and measure campaigns against outcomes. The Tech Lab’s launch post says the specification addresses deduplication during processing, data quality verification and event type classification across upper-funnel, mid-funnel, lower-funnel and custom actions, not just conversions. It supports real-time and batch delivery, and an ext object lets a platform add its own fields without breaking the shared structure.
That post describes adoption for advertisers already sending server-side events in plain terms: “it starts as a mapping exercise.” A team reviews its event taxonomy against ECAPI’s standard event types, maps user fields into the user_data object and aligns its event_id approach with the spec’s deduplication method.
What the clean room guidelines add
An earlier Tech Lab post, Unlock Faster Data Clean Room Integrations with ECAPI, explains why the guidance exists. Implementers found that marketing events are commonly analyzed with partners in data clean rooms. Wittkopp wrote, “The data clean room use case doesn’t warrant its own standard.” The events needed for measurement and optimization are the same as in the server-to-server integration, she explained, but the way event data is packaged for a clean room had enough nuances that guidance seemed beneficial.
The guidelines help in four areas, according to that post:
- Hashing and encryption: how a sender communicates the way to decrypt and access protected fields.
- Parquet schemas: when to use a nested structure and when to use a fully denormalized one.
- Partitioning: a common understanding of the partitioning schemes a recipient could support, and best practices for using them.
- File metadata: the core facts a sender and a receiver need so the data set is processed as the sender expects.
The Tech Lab also clarified hashing and encryption in the ECAPI standard itself. That new section is open for public comment as part of ECAPI 1.1. Wittkopp stated the aim plainly: “The ultimate goal of the ECAPI Guidelines for Data Clean Rooms is to help scale and expedite these integrations.”
What it means for the marketing leader
Conversion events are the raw material for measurement, and clean rooms are where many advertisers and publishers compare them. Every clean room integration that starts from a different file layout adds engineering time before anyone reads a result. A shared layout moves that time out of the first project and into the template.
The guidelines also set limits that a buyer should know. They are written for Parquet files. A clean room that receives data through live tables, governed shares or an API is outside them, so the delivery method is the first fact to confirm with each partner. They cover data moving between systems, so how a clean room stores and processes the data stays a matter for the contract.
The guidelines arrive while other industry bodies are working on measurement too. We covered the IAB’s cross-channel measurement decision guide, which was open for comment until November 4, and the Tech Lab chief operating officer’s case for Trusted Server as an answer to Apple’s restrictions.
The launch post also sets out what each side of a deal is expected to do. Advertisers share outcome signals such as sales, visits and leads through standardized server-side methods, focus on key outcomes and map existing events to ECAPI. The post says an advertiser does not need new events, “just alignment with the standard.” Publishers and platforms support ECAPI as a standard format for incoming signals, and the post says each integration built to it reduces engineering work and speeds onboarding.
In our reading, the practical value of ECAPI sits with the team that already owns a clean room contract. A written event list, mapped once to ECAPI’s event types, can be reused with every new partner instead of being rebuilt each time.
The hashing and encryption clarification deserves a read from whoever signs the data agreement. The Tech Lab says the new guidance helps senders communicate how to decrypt and access protected fields, which is a step that otherwise gets settled by email between two engineering teams. Writing it into the standard gives both sides a reference to point to when a transfer fails.
What to do this quarter
- List the conversion events you send today to platforms, and note which are upper-funnel, mid-funnel, lower-funnel or custom.
- Ask each clean room partner how it receives event data, and whether Parquet files are one of the options.
- Ask who decrypts hashed fields, and where the method is documented, before a data transfer starts.
- Read the hashing and encryption section in ECAPI 1.1 and send comments while it is open.
- Name one person who owns the event mapping, so it changes in one place.
Source: IAB Tech Lab
