Senior Backend Engineer, AI

Caspar Health

. Take full end-to-end ownership of features across implementation, automated testing, release, and live operation .

Posted 10/22/2026full-timeRemote • GermanySenior💰 €78,000 - €88,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in developing scalable Ruby on Rails services and robust APIs while owning features from implementation to live operation. Strong collaboration with product and domain experts to ensure high-performance software delivery and adherence to modern testing standards.

Highest-signal resume keywords

Ruby On Rails DevelopmentAPI DesignLLM Application DevelopmentAuthorization ConceptsAutomated Testing Strategies

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Ruby On RailsAPI DevelopmentData ModelingBackground Job ProcessingLLM ApplicationsEvaluation PipelinesAgent WorkflowsAutomated TestingBilling WorkflowsTechnical Decision-Making

Soft Skills

Strong CommunicationCollaboration

Industry Keywords

Complex SystemsOperational MonitoringDelivery PracticesEngineering Standards

Tech Stack

Tools & technologies

RubyRuby on Rails

About the role

Key responsibilities & impact

Take full end-to-end ownership of features across implementation, automated testing, release, and live operation
Develop scalable Ruby on Rails services, robust APIs, data models, and background jobs
Build and optimize LLM applications, evaluation pipelines, and agent workflows with repeatable quality checks
Implement authorization and billing workflows
Collaborate closely with the Product Manager and domain experts to turn complex requirements into maintainable, high-performance software
Contribute through technical reviews, operational monitoring, and explicit technical decision-making
Shape shared delivery practices and establish modern testing and engineering standards across the team

Requirements

What you’ll need

Strong senior experience in building and maintaining complex systems using Ruby on Rails
Proven expertise in designing clean APIs, data models, and managing background job processing
Sound understanding of authorization concepts, billing workflows, and automated testing strategies
Practical experience building LLM applications, evaluations, and agent workflows
Ability and mindset to own functionality independently from initial design to live production
Strong communication skills to collaborate with product and domain experts and make technical trade-offs explicit
Must be eligible to work in Germany and resident from the first day
Visa sponsorship and relocation assistance are not available

Benefits

Comp & perks

Remote-first with flexible working hours
Office optional in Berlin-Mitte
Up to 90 days a year outside of Germany
Monthly home office allowance
Additional meal subsidy
30 vacation days per year
Budget for learning & development, conferences, and coaching
High level of ownership and decision-making freedom
Access to all Caspar offerings for mental and physical well-being
Snacks, group sports sessions, drinks fridge, and humor