Freelance Integration Engineer - HR Systems

Company Intro At Toloka AI we create data that powers leading GenAI models and innovations. We work with frontier labs, big tech, renowned AI startups, enterprises and non-profit research organizations worldwide. We use a combination of Experts + Crowd + Tech Platform to teach AI models to reason and evaluate their efficacy and safety. We have experts in more than 50 different domains—from doctors and lawyers to physicists and engineers—and boast one of the most diverse global crowds, representing over 100 countries and speaking 40+ languages. We are a well-funded startup with an enviable portfolio of clients including Anthropic, Amazon, Microsoft, Poolside, Recraft, and Shopify. Recently, we secured strategic investment led by Bezos Expeditions and Nebius Group with participation from Mikhail Parakhin, CTO of Shopify and board advisor to leading GenAI companies, who now serves as our Chairman of the Board. Our remote-first team is globally distributed around the world: USA, UK, the Netherlands, Serbia, and more. About position We're looking for a freelance Integration Engineer to join our Corporate Infrastructure team. You'll build and maintain the integrations that connect our people systems — making our ATS, HRIS, project tracking tools, and surrounding infrastructure communicate reliably and securely. This is a hands-on technical role: analyzing requirements, designing webhook flows and integration architecture, building and debugging integrations, implementing security requirement, and ensuring data moves correctly between systems. You'll work on an hourly basis against a prioritized backlog, but you're expected to help shape it, proposing solutions and owning the design, with product direction from the HR Tech owner and technical oversight from Engineering. Responsibilities 1. Solution Design & Business Analysis - Understand existing processes and pain points, and translate ambiguous or high-level requirements into concrete technical solutions - Define the target architecture for each data flow: systems of record, sync direction and frequency, event-driven vs. batch, and the error/reconciliation strategy - Create design and technical documentation 2. Integration Development & Maintenance - Build and maintain integrations between people systems (ATS, HRIS, project tracking tools) - Design and implement webhook connections and event-driven data flows - Own field mapping and data transformation between systems with differing schemas - Migrate legacy integrations and update them to reflect current business logic - Ensure data is correctly propagated end-to-end across connected systems 3. Security & Reliability - Handle PII to a high standard: data minimization, least-privilege API scopes, secrets management and audit trails - Audit integrations on a BAU basis - verifying data is processed, synced, and stored correctly - Implement monitoring and error-handling to catch failures early Requirements - Solid experience building and maintaining system integrations via REST APIs and webhooks - Strong Python for scripting, automation, and integration logic - Experience with cloud infrastructure - Azure is a plus - Comfortable with secure data handling: OAuth2 / API-key auth, webhook signature verification, secrets management, handling of sensitive PII - Able to own design decisions and documenting trade-offs independently, not only executing a predefined spec - Able to work with Jira as part of a broader technical workflow Ways of Working - Self-directed and able to pick up tasks from a backlog independently - Good at communicating progress and flagging blockers - Comfortable in a remote, async environment Nice to Have - Prior experience integrating with HRIS or ATS platforms (HiBob, Greenhouse, Workday, or similar) as a developer - Familiarity with CosmosDB or similar NoSQL stores - Infrastructure-as-Code on Azure What we can offer Freelance collaboration (B2B) via the Ontop freelance platform.Flexible, fully remote schedule (40 hours per week).You’ll have the opportunity to work on highly innovative projects at the leading edge of AI development, together with a genuinely dedicated and dynamic team of experts.You’ll also be working on projects with customers that are AI industry leaders and well-known household names.Friendly community.