Senior Backend Engineer – Rust & Scala Security Platform

Halcyon; United States; Remote; USD 120,000 - 170,000; Full time

Benefits offered by this job

Comprehensive healthcare

401k plan with employer contribution

Disability & life insurance

FSA options

Flexible PTO

Parental leave

Generous equity

Job summary

Halcyon, a remote-native cybersecurity startup, is seeking a Senior Backend Engineer to join the cloud team and lead the development of our data platform and API services in a Scala and Rust stack.

The role emphasizes ownership of backend services, with opportunities to guide migration to Rust and contribute to a security analysis platform that includes malware analysis engines, threat detection, and ML workflows.

Qualifications

• 5+ years of backend engineering experience, with recent experience in a JVM-based codebase.
• Experience designing and owning distributed systems from start to finish.
• Experience with Rust, or a well-formed view of when it's the right tool, and the ability to help guide a migration.
• Strong understanding of APIs, messaging systems (Kafka), and modern data stores (Postgres, DynamoDB, OpenSearch).
• Experience building services in a cloud-native environment, preferably AWS.
• Working knowledge of containers and Kubernetes.
• Comfortable working in a remote-first, asynchronous team environment.

Responsibilities

• Lead the design and delivery of features across our data platform and public API services, including ingestion, transformation, and enrichment of security data.
• Drive system design, architecture, and data flow decisions in partnership with product and platform engineering.
• Build, deploy, and own Scala-based backend services in production, keeping them reliable, secure, and performant.
• Help shape and execute our migration of selected APIs from Scala to Rust, ensuring consistency and continuity along the way.
• Set the bar for code quality, documentation, and operational excellence.
• Lead design reviews, code reviews, and take part in on-call and incident response.
• Support and enhance our Python-based security analysis platform, including malware analysis engines, automated threat detection, and machine learning model workflows.

Skills

Backend engineering

Distributed systems

Rust

APIs, Kafka, data stores

AWS

Containers & Kubernetes

Remote-first / asynchronous

Python development (security analysis)

Tools

Databricks

ClickHouse

Terraform

Helm

GitHub Actions

Prometheus

Grafana

CloudWatch

Kubernetes

Job description

Senior Backend Engineer – Rust & Scala Security Platform — Remote

Compensation vs. Market: The $120,000–$170,000 base range is competitive for a senior backend engineer but sits at the mid-to-lower end for a senior IC role at a venture-backed cybersecurity startup in 2024–2025, where top-of-market is often $180k–$220k+. The 10% bonus target and "generous equity" can close this gap meaningfully if the company exits successfully — Halcyon raised a $100M Series C in 2024, suggesting real growth momentum.

High-Demand Skill Development: This role is a rare opportunity to work across Rust, Scala, and Python in a production security context. Rust expertise is one of the most sought-after skills in systems engineering right now, and leading a Scala-to-Rust migration puts you at the forefront of that transition. Security-domain backend experience (malware analysis, threat detection pipelines) commands a significant premium in the job market.

• Green flag: Founded by veterans from FireEye, Cylance, IBM X-Force — strong pedigree and credibility in the market.
• Green flag: Clear ownership model — you "lead" features, own systems end-to-end, and influence architectural direction.
• Green flag: Remote-native culture since founding (2021), suggesting genuine async competence rather than reluctant remote.
• Watch out for: On-call and incident response responsibilities are real — scope this carefully in interviews.

For engineers wanting to deepen expertise in distributed systems, security engineering, and Rust, this role offers an unusually broad technical surface area at a growth-stage company with a clear product niche.

What we do:

Halcyon is the industry's first dedicated, adaptive security platform that combines multiple proprietary advanced prevention engines along with AI models focused specifically on stopping ransomware.

Who we are:

Halcyon was formed in 2021 by a team of cyber industry veterans after battling the scourge of ransomware (and advanced threats) for years at some of the largest global security vendors. Comprised of leaders from Cylance (now Blackberry), Accuvant (now Optiv), FireEye and ISS X-Force (now IBM), Halcyon is focused on building products and solutions for mid-market and enterprise customers.

The Role

At Halcyon, we're building a world-class anti-ransomware platform grounded in innovation and resilience. As part of that vision, we're looking for a Senior Backend Engineer to join our cloud team. You'll lead the development and evolution of our data platform and API services, working within a modern tech stack that blends Scala and Rust.

You'll join a team focused on building scalable, maintainable backend systems that serve both internal and customer-facing functions. Your primary focus will be on Rust and Scala services, with opportunities to shape our transition to Rust where it makes sense. Python development experience is highly valued, particularly for supporting our security analysis platform which includes malware analysis engines, automated threat detection, and machine learning workflows.

Responsibilities

• Lead the design and delivery of features across our data platform and public API services, including ingestion, transformation, and enrichment of security data.
• Drive system design, architecture, and data flow decisions in partnership with product and platform engineering.
• Build, deploy, and own Scala-based backend services in production, keeping them reliable, secure, and performant.
• Help shape and execute our migration of selected APIs from Scala to Rust, ensuring consistency and continuity along the way.
• Set the bar for code quality, documentation, and operational excellence.
• Lead design reviews, code reviews, and take part in on-call and incident response.
• Support and enhance our Python-based security analysis platform, including malware analysis engines, automated threat detection, and machine learning model workflows.

Skills and Qualifications

• 5+ years of backend engineering experience, with recent experience in a JVM-based codebase.
• A track record of designing and owning distributed systems from start to finish.
• Experience with Rust, or a well-formed view of when it's the right tool, and the ability to help guide a migration.
• Strong understanding of APIs, messaging systems (Kafka), and modern data stores (Postgres, DynamoDB, OpenSearch).
• Experience building services in a cloud-native environment, preferably AWS.
• Working knowledge of containers and Kubernetes.
• Comfortable working in a remote-first, asynchronous team environment.

Bonus Skills and Qualifications

• Familiarity with functional programming patterns and idiomatic Scala.
• Experience with Databricks and ClickHouse (or similar lakehouse and analytical/OLAP data stores).
• Experience with Terraform, Helm, and GitHub Actions.
• Familiarity with observability tools (Prometheus, Grafana, CloudWatch).
• Prior work on security products, data pipelines, or high-availability systems.
• Python development experience, particularly with security analysis tools and malware detection frameworks (YARA, PE analysis, binary analysis).
• Familiarity with machine learning workflows, AutoML, and MLflow for model deployment and management.
• Experience with binary analysis libraries (LIEF, ssdeep, TLSH) and security tooling integration.

Halcyon offers the following benefits to eligible employees:

• Comprehensive healthcare (medical, dental, and vision) with premiums paid in full for employees and dependents.
• 401k plan with a generous employer contribution.
• Short and long-term disability coverage, basic life and AD&D insurance plans.
• Medical and dependent care FSA options.
• Flexible PTO policy.
• Parental leave.
• Generous equity offering.

The Company reserves the right to modify or change these benefits programs at any time, with or without notice.

Base Salary Range:

$120,000 - $170,000

In accordance with applicable state and federal laws, the range provided is Halcyon's reasonable estimate of the base compensation for this role. The actual amount may differ based on non-discriminatory factors such as experience, knowledge, skills, abilities, and location. Base pay is one part of the total package that is provided to compensate and recognize employees for their work, and this role may be eligible for additional discretionary bonuses/incentives, and equity in the Company.

We understand it takes a diverse team of highly intelligent, passionate, curious, and creative people to develop the exceptional product we are building. Our dynamic team has incredible perspectives to share, just as we know you do, and we take great pride in being an equal opportunity employer.

Is this role fully remote or does it require being in an office? This role is fully remote. Halcyon is a remote-native, completely distributed global team. However, the position is restricted to candidates based in the United States. What is the salary range for this Senior Backend Engineer position? The base salary range is $120,000–$170,000 annually, with a 10% bonus target. The role also includes equity in the company and a full benefits package including fully paid healthcare premiums. Do I need to know both Rust and Scala to apply? Recent experience in a JVM-based codebase (such as Scala) is required, while Rust experience is listed as a qualification — either direct experience or a well-informed perspective on when to use it. You'll help guide a migration from Scala to Rust. Is there an on-call requirement for this position? Yes, the role includes participation in on-call rotations and incident response as part of owning backend services in production. Is Python experience required for this backend role? Python is not listed as a required skill but is highly valued, particularly for supporting the security analysis platform which includes malware analysis engines, threat detection, and ML workflows. It's listed as a bonus qualification.

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