Table of Contents
Overview
LMT (Limit Ad Tracking) is a device-level privacy signal sent by mobile apps when a user opts out of personalized advertising.
When lmt=1 is present in a bid request, it means:
The user has requested not to be tracked.
Personal identifiers (PII) such as device IDs and geolocation should not be used.
This signal is commonly seen in:
COPPA (children's) inventory
Privacy-focused apps and OS settings
Android environments where users opt out of ad personalization
The platform's logic for handling LMT=1 bid requests applies automatically to all traffic. It is aligned with IAB’s interpretation of LMT and is COPPA/CCPA-compliant.
How FreeWheel DSP Solutions Processes LMT=1 Bid Requests
All bid requests with lmt=1 are accepted, across all devices and operating systems.
To comply with privacy regulations, FreeWheel enforces the following behaviors:
Personal Data Obfuscation Behavior
The following commonly used RTB fields are considered "Personal Data". To protect this data, bid requests flagged with LMT=1 will have changes made to the following fields when passed in macros, bidding agent requests, augmentor requests, and log files:
Raw Log Field Name | Proto Field Name | Data Handling |
|---|---|---|
platform_device_ifa | Device.ifa | Blank |
platform_device_idfa | Device.idfa | Blank |
platform_device_didmd5 | Device.didmd5 | Blank |
platform_device_didsha1 | Device.didsha1 | Blank |
platform_device_dpidmd5 | Device.dpidmd5 | Blank |
platform_device_dpidsha1 | Device.dpidsha1 | Blank |
user_id | N/A | Blank |
geo_lat | Device.lat | Truncated to 3 decimal places |
geo_long | Device.long | Truncated to 3 decimal places |
ua | Device.ua | Blank |
ip_address | Device.ip | Truncated to 3 octets |
ipv6_address | Device.ipv6 | Truncated to 6 octets |
inventory_source_user_id | User.id | Blank |
Fields Added to LMT=1 Bid Requests
In addition to the changes made to fields listed above, the following fields will be added to all records with LMT=1:
Field | Value |
|---|---|
user_id_hashed | N/A |
ip_address_hashed | DeviceExtensions.ip_hashed |
ipv6_address_hashed | DeviceExtensions.ipv6_hashed |
LMT=1 Limitations
Targeting Limitations
- Audience targeting is blocked.
- Precise geo-targeting, such as latitude/longitude and IP address targeting, is blocked.
Logging and Macros
- Raw personal data is not available in logs.
Device ID, geo, and user ID macros will not resolve in creatives or logs.
Campaign Performance
- These limitations will not affect how campaigns behave, as targeting limitations are enforced at the platform level.