Senior Software Engineer - Android Systems & Security

United States·San FranciscoFull-Timesenior

Software EngineerSoftware Engineering

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Quick Summary

Requirements Summary

Implement new locking features that interact with system-level services for example Telephony, Power Management, and Device Policy Manager,

Technical Tools

Software EngineerSoftware Engineering

About PayJoy

PayJoy, a Public Benefit Corporation, is a mission-first credit provider dedicated to helping under-served customers in emerging markets to achieve financial stability and success. Our patented technology for secured credit provides an on-ramp for new customers to enter the credit system. Through PayJoy’s point-of-sale financing and card offerings, customers gain access to a modern quality of life. PayJoy’s credit also allows our customers to seize opportunities as micro-entrepreneurs, and acts as insurance for tough times. Through our cutting-edge machine learning, data science, and anti-fraud AI, we have served over 18 million customers as of 2025 while achieving solid profitability for sustainable growth.

This role

This is not a conventional Android app development role (building applications for the Play Store). We are seeking a specialized systems engineer focused on the heart of the operating system: AOSP (Android Open Source Project) and the TEE (Trusted Execution Environment).

In this role, you will bridge the gap between high-level Android features and low-level hardware integration, ensuring our proprietary security mechanisms—which protect our assets at the OS level—are robust, performant, and tamper-proof.

Framework Engineering: Develop and maintain custom modifications within the Android Framework (AOSP) and Hardware Abstraction Layers (HAL).

OEM Integration: Partner with global smartphone manufacturers and chipset vendors to integrate PayJoy’s proprietary technology into factory firmware.

Cross-Border Collaboration: Work daily with our China-based engineering team to align on technical specifications and manufacturing requirements.

Feature Development: Implement new locking features that interact with system-level services for example Telephony, Power Management, and Device Policy Manager, etc…

R&D & Debugging: Use deep chip-level knowledge to troubleshoot integration issues across different silicon providers (Qualcomm, MediaTek, etc.).

Process Automation: Contribute to OTA (Over-the-Air) updates and global device testing.

Android Internals Expertise: Extensive, hands-on experience with AOSP development, including modifying system services and utilizing the Android build system (Soong/Make).
Low-Level Language Mastery: Expert-level proficiency in Java and C/C++ (JNI). (Ability to read/write Kotlin is expected, but core work remains at the system level).
OEM/Firmware Background: Proven experience working with or for an OEM or chipset vendor on firmware customization, device bring-up, or security hardening.
Strong Core Skills: Demonstrable knowledge of AOSP and TEE / ARM TrustZone.
⚠️ Note: If your background is primarily focused on building consumer-facing commercial apps (e.g., banking, gaming, or general retail apps), this role will not be a match for your skillset.

Nice to Have

~2 min read

Experience with Secure Boot, verified boot (AVB), and common Android exploit vectors.
Automation of firmware build pipelines and signing processes using Python or Bash.
Comfort collaborating effectively with international teams across different time zones.

💬 Ready to solve complex engineering challenges that almost no one else in the industry is tackling? Apply directly or send me a DM. Let's chat!

Local benefits depending on the country of hire

Company-funded health insurance for employee and immediate family

Company-funded employee life and disability insurance

Paid vacation days, unlimited sick leave

$2,000 USD annual Co-working travel perk

$2,000 USD annual Professional Development perk

Phone finance, headphone benefit, home office equipment allowance and wellness perks

Catered lunches

PayJoy is proud to be an Equal Employment Opportunity employer and we welcome and encourage people of all backgrounds. We do not discriminate based upon race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristics.

PayJoy Principles

Finance for the next billion * Ownership * Break Through Walls * Live Communication * Transparency & Directness * Focus on Scale * Work-Life Balance * Embrace Diversity * Speed * Active Listening