Software Development Engineer III - API Platform

About HighLevel:HighLevel is an AI powered, all-in-one white-label sales & marketing platform that empowers agencies, entrepreneurs, and businesses to elevate their digital presence and drive growth. We are proud to support a global and growing community of over 1 million businesses, comprised of agencies, consultants, and businesses of all sizes and industries. HighLevel empowers users with all the tools needed to capture, nurture, and close new leads into repeat customers. As of mid 2025, HighLevel processes over 4 billion API hits and handles more than 2.5 billion message events every day. Our platform manages over 470 terabytes of data distributed across five databases, operates with a network of over 250 microservices, and supports over 1 million hostnames.Our PeopleWith over 1,500 team members across 15+ countries, we operate in a global, remote-first environment. We are building more than software; we are building a global community rooted in creativity, collaboration, and impact. We take pride in cultivating a culture where innovation thrives, ideas are celebrated, and people come first, no matter where they call home.Our ImpactAs of mid 2025, our platform powers over 1.5 billion messages, helps generate over 200 million leads, and facilitates over 20 million conversations for the more than 1 million businesses we serve each month. Behind those numbers are real people growing their companies, connecting with customers, and making their mark - and we get to help make that happen.About the Role:We are looking for a software engineer to help evolve our public and internal API ecosystem. In this role, you’ll design and build API frameworks, contribute to our long-term versioning strategy, and work on the core platform that powers thousands of partner integrations and developers.You’ll collaborate closely with other engineers, product managers, and platform teams to make our API surface reliable, scalable, and easy to use, helping us deliver a great developer experience in a fast-growing, multi-tenant SaaS environment.This role is ideal for someone who:--> Has strong experience building APIs in large-scale SaaS platforms--> Has worked with public-facing or internal API frameworks used by multiple teams--> Cares deeply about platform consistency, lifecycle management, and clear architecture--> Operates at a Senior / SDE III level, driving projects end-to-end and influencing design across teamsResponsibilities:Implement and evolve core API platform components used by product teams (e.g., shared middleware, base controllers, common utilities)Contribute to and uphold API governance standards—request/response schemas, naming conventions, error envelopes, authentication patterns, and security guidelinesParticipate in API lifecycle management (versioning, migrations, deprecations, and compatibility) and help define best practices for teamsBuild and maintain tooling for SDK generation, documentation automation (OpenAPI-driven), contract validation, and developer onboarding workflowsDesign and implement features in multi-tenant, high-traffic API systems handling millions of requests/dayBuild and improve frameworks for API reliability: rate limiting, circuit breaking, retry semantics, idempotency, and data consistency patternsContribute to the architecture of secure and resilient integration pipelines such as webhooks, events, streaming services, and async workflowsHelp shape a great API developer experience through consistent API design, clear docs, and intuitive onboarding flowsContribute to an internal API catalog / schema registry, making it easier for teams to discover and reuse APIsImprove API observability by implementing structured logging, telemetry hooks, and contributing to SLO-based dashboards and API analyticsWork with product managers and leads to break down platform requirements into clear technical designs and deliverablesPartner with other engineering teams on API modeling, minimizing breaking changes and enabling backwards-compatible evolutionProvide technical mentorship to junior and mid-level engineers, sharing best practices in API and platform engineeringParticipate in and occasionally lead design reviews, RFCs, and architecture discussions related to the API platformRequirements:4+ years of professional software engineering experience, including 2+ years working on large-scale SaaS products or platformsProven experience designing or implementing public-facing APIs, internal platforms, or integration ecosystemsStrong understanding of: API paradigms [REST, GraphQL, event-driven APIs], Versioning strategies [URL-, header-, media-type–based, and resource evolution], Authentication & security [OAuth2.0, JWT, HMAC, scopes] & Schema evolution & API contracts [OpenAPI/Swagger, contract testing]Solid coding skills in JavaScript/TypeScript and Node.js (or a similar backend stack) with experience in production systemsExperience with distributed systems concepts: queues, event buses, CRON / schedulers,