Towards Understanding Android APIs: Official Lists, Vendor Customizations, and Real-World Usage

2026-04-16

AI Summary

Official Android API lists (AALs) suffer from inconsistencies and instability, severely undermining the reliability and reproducibility of API-based Android research. This study systematically examines discrepancies among four widely used AALs, their version evolution, and real-device availability, complemented by large-scale static analysis of 17,759 applications. For the first time, it uncovers underlying policy divergences and the pervasive use of vendor-customized APIs. The findings reveal that substantial differences across AALs can materially alter research conclusions, while existing studies largely overlook vendor-specific APIs. Based on these insights, the paper offers practical recommendations to improve the reliability of AAL selection and interpretation in future research.

Technology Category

• Application Domains: Mobility, Driving & Flight
• Philosophy and Ethics of AI: Applications
• Search and Optimization: Applications

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Android apps are built on APIs that abstract core Android system functionalities. These APIs are officially documented in multiple files distributed with the Android source code or SDK, which we collectively refer to as Android API Lists (AALs). Prior Android research has relied on specific AALs, often treating them as interchangeable ground truth. However, recent studies suggest that different AALs can lead to substantially different research outcomes, raising concerns about the validity and reproducibility of Android API-based analyses. To address this issue, we present the first in-depth empirical study of four official AALs that are widely used in prior work. We systematically characterize their contents and analyze their evolution across Android releases. We then perform a fine-grained comparison of the APIs recorded in each AAL to uncover their underlying API inclusion policies and inconsistencies. To assess the practical impact of these differences, we further examine API availability on nine Android devices, including both stock Android and vendor-customized systems. Finally, we analyze API usage in 17,759 real-world Android apps (including open-source apps, commercial apps, and malware) to quantify how the choice of AAL affects empirical Android research. Our results reveal that official AALs are neither stable nor mutually consistent, and that discrepancies among them can substantially influence research conclusions. We also observe that vendor-customized APIs are actively used by normal apps, yet remain largely overlooked by existing studies. Based on these findings, we discuss their implications for Android API-based research and provide actionable suggestions to help researchers select and interpret AALs more reliably.

Problem

• Android APIs
• API Lists
• Vendor Customizations
• Research Reproducibility
• API Inconsistency

Innovation

• Android API Lists
• API inconsistency
• vendor customization
• empirical study
• API usage analysis