Principal Back-End Engineer at toptal

About Toptal Toptal is a global network of top talent in business, design, and technology that enables companies to scale their teams, on-demand. With $200+ million in annual revenue and team members based around the globe, Toptal is the world’s largest fully remote workforce. We take the best elements of virtual teams and combine them with a support structure that encourages innovation, social interaction, and fun. We see no borders, move at a fast pace, and are never afraid to break the mold. Job Summary We’re seeking a Senior/Principal Back-end Engineer to join the Toptal Resume team, a small, high-velocity team building an AI-powered career services platform. This is a hands-on, execution-heavy role for someone with deep experience in Ruby on Rails, PostgreSQL, background jobs, API design, event-driven systems, and production-grade back-end architecture. We need a back-end specialist who can own critical platform capabilities, make sound technical decisions, and ship high-quality work quickly. The team operates with a startup-like mindset inside a larger company: small team, high ownership, fast delivery, direct collaboration with business stakeholders, and strong AI adoption as part of both the product and the engineering workflow. The modern stack includes Rails 7.1, YJIT, PostgreSQL, Sidekiq, Redis, and a modular monolith with well-structured domain boundaries. Tasks and Deliverables Build, maintain, and own Rails API capabilities across multiple business domain packs. Design and implement background job workflows with Sidekiq for async and parallel processing. Integrate and optimize LLM-based features for resume analysis, writing, and generation. Build and maintain event-driven systems using pub/sub patterns for cross-domain communication. Design PostgreSQL schemas and data models with strong attention to data integrity. Integrate third-party services, including payment processors, email providers, and cloud services. Maintain and evolve a modular monolith architecture with explicit package and domain boundaries. Collaborate closely with front-end and infrastructure teams on API contracts, deployment workflows, and production reliability. Use AI development tools daily to increase delivery speed, improve code quality, and explore implementation options. Work independently, communicate progress clearly, and take accountability for delivery. Required Experience Senior or Principal-level back-end engineering experience, with a strong delivery track record. 8+ years of professional Ruby on Rails development. Strong PostgreSQL skills, including schema design, migrations, relational modeling, and query optimization. Experience with async/background processing systems such as Sidekiq or equivalent. Redis proficiency, especially caching and session management. Strong REST API design and implementation experience at production scale. Experience integrating external APIs such as payment processors, email providers, cloud storage, or support platforms. Comfortable working in modular monoliths or similarly structured codebases with clear domain boundaries. Ability to reason about scalability, performance, observability, and data integrity. Strong technical ownership, including architectural judgment and accountability for implementation decisions. Fast, independent, methodical working style with strong written and verbal English communication. Daily use of AI development tools to accelerate development and improve engineering quality. Nice to Have Experience with LLM/AI API integrations such as OpenAI, Anthropic, or similar providers. Experience with GCP and Kubernetes-based deployment workflows. Experience with event-driven architecture using pub/sub systems or message queues. Stripe, a SaaS payment-flow or subscription-platform experience. Experience with document processing pipelines involving PDF, DOCX, OCR, or similar formats. Experience with feature flagging or observability tools such as Flipper, DataDog, Sentry, or Prometheus. Engagement Highlights Work on an AI-powered career services platform with real users and direct business impact. Work on a modern Rails 7.1 codebase with YJIT, modular packs, and well-structured domain boundaries. Build AI-powered features using the latest GPT models in a production system. Own meaningful back-end capabilities across APIs, async workflows, data models, integrations, and event-driven systems. Operate in an AI-first, high-velocity engineering culture where senior engineers have significant technical ownership and can meaningfully shape the architecture.