Senior Backend Engineer - Encryption & PHI Security

StackAI; United States; On-site; USD 248,000 - 282,000; Full time

Job summary

StackAI is seeking a senior Python engineer with a strong focus on security-critical product systems to join the Core Engineering team. You will build systems that encrypt data, manage keys and signatures, and enforce tenant and authentication boundaries across hosted, VPC, and on‑prem deployments.

You’ll work at the interface of architecture and implementation, translating security requirements into reliable, production‑grade features while evolving live systems with careful migrations and

Qualifications

• 4+ years of experience building and operating production backend systems.
• Strong professional experience with Python in a substantial production codebase.
• Hands‑on experience implementing security‑critical product systems, including the code that enforces their guarantees.
• Depth in encryption and key management, signing, authentication, sessions, or token infrastructure, multi‑tenant isolation, sensitive‑data processing, secure storage and runtime use of customer credentials.
• Practical knowledge of applied cryptography.
• Experience changing critical systems without disrupting existing customers or making previously stored data inaccessible.
• Strong judgment around trust boundaries, failure modes, and the consequences of compromise.
• The ability to take an ambiguous technical problem from investigation through production rollout.

Responsibilities

• Build encryption and key-management systems. Design and evolve how customer data is encrypted, how keys are scoped and rotated, and how these systems work across hosted, VPC, and on-premises deployments.
• Protect sensitive data. Build the controls that detect, transform, and safely handle PHI, PII, and other sensitive data across workflows, connectors, model calls, logs, and storage.
• Secure customer credentials. Protect the credentials and tokens customers provide to StackAI, from storage and access control through their use at runtime.
• Strengthen product trust boundaries. Improve tenant isolation, signing and verification, session and token handling, and service-to-service authentication.
• Create shared security foundations. Build Python services, libraries, and APIs that make security‑critical behavior consistent and straightforward for other engineers to use.
• Evolve live systems safely. Plan and execute migrations, compatibility periods, staged rollouts, observability, recovery, and rollback.

Skills

Python

Security‑critical systems

Encryption and key management

Multi‑tenant isolation

Sensitive‑data processing

Cryptography

Trust boundaries

Job description

StackAI is seeking a senior Python engineer with a strong focus on security-critical product systems to join the Core Engineering team. You will build systems that encrypt data, manage keys and signatures, and enforce tenant and authentication boundaries across hosted, VPC, and on‑prem deployments.

You’ll work at the interface of architecture and implementation, translating security requirements into reliable, production‑grade features while evolving live systems with careful migrations and