Senior Back-End Engineer

Description
We are
At Cross River, we're building the financial infrastructure that powers global innovation. With our cutting-edge suite of embedded payments, cards, and lending solutions, we enable millions of businesses and consumers to transact seamlessly and securely.

With 900+ employees worldwide and an R&D center of over 160 employees in Jerusalem - we're reshaping how financial technology is developed and delivered. .

THE ROLE
We are looking for a backend engineer who can design, build, and operate highly reliable services on AWS that enable generative‑AI capabilities across our products and internal workflows.

You will create scalable APIs, data pipelines, and serverless architectures that integrate large‑language‑model (LLM) services such as Amazon Bedrock, OpenAI, and open‑source models, enabling teams to safely and efficiently leverage generative AI.

Who You Are

• You have experience building Retrieval‑Augmented Generation (RAG) systems or knowledge‑base chatbots.
• You're Hands‑on with vector databases such as Pinecone, Chroma, or pgvector on Postgres/Aurora.
• Have AWS certification (Developer, Solutions Architect, or Machine Learning Specialty).
• Experience with observability tooling (Datadog, New Relic) and cost‑optimization strategies for AI workloads.
• Background in microservices, domain‑driven design, or event‑sourcing patterns.

What You'll Actually Be Doing

• Design and implement REST/GraphQL APIs in to serve generative‑AI features such as chat, summarization, and content generation.
• Build and maintain AWS‑native architectures using Lambda, API Gateway, ECS/Fargate, DynamoDB, S3, and Step Functions.
• Integrate and orchestrate LLM services (Amazon Bedrock, OpenAI, self‑hosted models) and vector databases (Amazon Aurora pgvector, Pinecone, Chroma) to power Retrieval‑Augmented Generation (RAG) pipelines.
• Create secure, observable, and cost‑efficient infrastructure as code (CDK/Terraform) and automate CI/CD with GitHub Actions or AWS CodePipeline.
• Implement monitoring, tracing, and logging (CloudWatch, X‑Ray, OpenTelemetry) to track latency, cost, and output quality of AI endpoints.
• Collaborate with ML engineers, product managers, and front‑end teams in agile sprints; participate in design reviews and knowledge‑sharing sessions.
• Establish best practices for prompt engineering, model evaluation, and data governance to ensure responsible AI usage.

Requirements
What You Bring to the Table

• Available working some US hours
• Proficient in Hebrew and English both written and verbal, sufficient for achieving consensus and success in a remote and largely asynchronous work environment - Must
• 4+ years professional experience building production services with
• 3+ years hands‑on with AWS, including Lambda, API Gateway, DynamoDB, and at least one container service (ECS, EKS, or Fargate).
• Experience integrating third‑party or cloud‑native LLM services (e.g., Amazon Bedrock, OpenAI API) into production systems.
• Strong understanding of RESTful design, GraphQL fundamentals, and event‑driven architectures (SNS/SQS, EventBridge).
• Proficiency with infrastructure‑as‑code (AWS CDK, Terraform, or CloudFormation) and CI/CD pipelines.
• Familiarity with secure coding, authentication/authorization patterns (Cognito, OAuth), and data privacy best practices for AI workloads.

Technical Environment:

• Languages: TypeScript, JavaScript, SQL
• Frameworks & Libraries: , Fastify, Apollo Server, LangChain‑JS, AWS SDK v3
• Datastores: DynamoDB, Aurora (Postgres + pgvector), Redis, S3
• Infra & DevOps: AWS Lambda, API Gateway, ECS/Fargate, Step Functions, CDK, Terraform, Docker, GitHub Actions
• AI Stack: Amazon Bedrock, OpenAI API, HuggingFace Inference Endpoints, Pinecone, Chroma

WHY YOU'LL LOVE WORKING HERE
We're a collaborative, humble, and fast-paced team that takes pride in building real solutions to real problems. You'll work on meaningful products that empower businesses and people, alongside curious, supportive teammates who are always up for a challenge. Innovation and ownership are part of our DNA—and we're just getting started.

NEXT STEP
Hit Apply. Bring your AI vibes. We'll bring the challenge - and the snacks.