Yauaa: Yet Another UserAgent Analyzer

This is a java library that tries to parse and analyze the useragent string (and when available the User-Agent Client Hints) and extract as many relevant attributes as possible.

Works with Java, Scala, Kotlin and provides ready for use UDFs for several processing systems.

The full documentation can be found here


In a specific case of bad data in the Client Hints yauaa 7.0.0-7.8.0 will throw an ArrayIndexOutOfBoundsException.

See Security Advisory: CVE-2022-23496

HIGH Profile release notes:

Version v7.17.0

  • Analyzer:
    • Use all testcases (including ClientHints) when doing preheat.

Version 7.16.0

  • Build:
    • Updated docker based environment to Ubuntu 22.04 LTS
    • The Quarkus example can now also be built into a native executable
    • Workaround Multi Release jar and maven-shade-plugin with relocation.

Version 7.15.0

  • New/improved detections
    • Full list of documented Yandex robots.
    • Extra noise filter of unwanted extra fields
    • Detect device and OS with WhatsApp
  • Build:
    • Improve plugin and dependency version management
    • Reproducible builds
      • Pin build timezone to UTC
      • Test script to verify reproducibility

Version 7.14.1

  • Build:
    • Reproducible builds
    • Update Snakeyaml to fix CVE

Version 7.14.0

  • New/improved detections
    • Alamofire/macOS Catalyst, Alamofire is NOT a LayoutEngine
  • Build:
    • Pubish SBOM
    • Reproducible builds
  • Analyzer
    • Workaround for resource loading problems works with dropTests

Version 7.13.0

  • Analyzer:
    • Adding VFS support back in.
  • New/improved detections
    • Extra noise filter of unwanted extra fields
    • Handle a new form of iOS apps.

Regarding the recent Log4J2 issues

The Yauaa analyzer uses the Log4J2 API to do the logging.


  • The core of Yauaa is safe as it does not include any logging dependencies and expects the application to provide everything.
  • In normal operations user input is not logged.
  • The Snowflake UDF is affected by these problems (due to shading the dependencies in).

NO batteries included

By design the Yauaa library expects the application in which it is used to provide the actual logging dependencies and configuration. If you do not provide the needed logging classes it will simply fail at startup.

So by design the Yauaa library expects all of these frameworks to be provided (and configured) and does not include any of them or any configuration for them.

This is true for most of the released artifacts (including the base library) except for the Snowflake UDF which does include almost all dependencies. So the Snowflake UDF IS affected by this issue and all users are recommended to update.

Minimal logging

Note that Yauaa does not log any user input and/or analysis results from user input during normal operation. Only during development and during unit tests the Useragents are logged.

This is because it was designed to run in very large scale batch and streaming situations (very large as in “Let’s analyze these 10^10 records”).

Bring your own batteries

To assist in running Yauaa without the logj4-core jar an example was created that only uses SLF4J: here.


If this project has business value for you then don’t hesitate to support me with a small donation.

Donations via PayPal


Yet Another UserAgent Analyzer
Copyright (C) 2013-2023 Niels Basjes

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.