Senior Software Engineer - Android Systems & Security

Payjoy · San Francisco, CA

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.

Responsibilities

  • 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.

  • Requirements

    • 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.

    • 🌟 Desirable Skills (Pluses):

      • 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!

    Benefits

  • 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
  • Apply →