Senior Backend-Focused Full-Stack Engineer

Samuel Liu

Summit, IL • ****.***.***@*****.*** • 323-***-**** • LinkedIn

SUMMARY

Backend-leaning full stack engineer with 12+ years of experience. Currently building LLM workflows and agent features with Python, FastAPI, React, and TypeScript. Earlier work covers 7 years on production tooling at Netflix Studio Engineering and 5 years on core messaging and APIs at Slack from beta launch through scale. Comfortable owning a feature end to end, from API design and data model to UI and on- call.

SKILLS

Languages: Python, TypeScript, JavaScript, PHP, Hack, Java, Kotlin, SQL Backend: FastAPI, Spring Boot, Node.js, REST APIs, GraphQL (DGS, Federation) Frontend: React, Next.js, TypeScript, Redux, React Flow AI / LLM: OpenAI, Anthropic, RAG pipelines, embeddings, prompt evaluation, pgvector Data: PostgreSQL, MySQL (sharded), Redis, Kafka, Cassandra, Solr Infra: AWS, Docker, Kubernetes, GitHub Actions, Spinnaker, Titus EXPERIENCE

StackAI 04/2025 - 04/2026

Senior Software Engineer Remote (Illinois)

• Designed and built multi-agent orchestration nodes for the no-code workflow builder, covering planner, tool-use, and routing steps.

• Built FastAPI endpoints for workflow execution, run history, and token streaming back to the React canvas.

• Implemented RAG pipelines on Postgres with pgvector, including document ingestion, embedding generation, and hybrid retrieval with re-ranking.

• Built React and Next.js components for the workflow canvas, including node configuration panels, live run logs, and error states.

• Designed an LLM provider abstraction supporting OpenAI, Anthropic, Google, and Meta models, with fallback, per-run cost tracking, and prompt version pinning.

• Wrote an offline evaluation harness that replays prompt and workflow changes against production traces and shows diffs before release.

• Added enterprise features like SSO, role-based access, and audit logs to support SOC 2 and HIPAA customers.

• Built ingestion connectors for SharePoint, Google Drive, and Slack so customers could populate knowledge bases from existing sources.

• Worked closely with founders and product on weekly scope, owned features end to end from API design through UI.

• Took on-call for the workflow execution service and the RAG layer. Netflix 05/2018 - 02/2025

Senior Software Engineer, Studio Engineering Los Gatos, CA (later remote)

• Built React and TypeScript front ends for Studio apps used by production crews, including scheduling, distribution, and content ops tools.

• Wrote Python services and scripts for content metadata pipelines, asset checks, and data fixes across the content lifecycle.

• Built backend services in Java and Kotlin on Spring Boot for Studio production tooling, with REST and gRPC endpoints.

• Worked on early Prodicle Distribution, including the Google Drive integration that productions used to share call sheets and shooting schedules.

• Converted a Studio REST service into a GraphQL Domain Graph Service (DGS) and registered its schema with the federated gateway during the Federation rollout.

• Owned a domain subgraph in the Studio graph as Federation expanded across teams, including schema evolution and breaking-change reviews.

• Migrated a document distribution async workflow to the Cosmos platform, which improved observability and cut support tickets after rollout.

• Built React and TypeScript internal tools for content ops to preview, tag, and schedule metadata changes across regions, replacing slower legacy tools.

• Wrote Python tooling for offline data jobs and ad hoc analysis on top of S3 and Iceberg.

• Set up tracing, metrics, and alerts with Atlas, Edgar, and TellTale for the services I owned, and ran the on-call rotation for my team.

• Led schema design for cross-team graph integrations as the Studio graph grew to around 200 DGSs.

• Mentored four engineers, ran design reviews, and helped onboard new hires to the Studio stack. Slack 09/2015 - 04/2018

Full Stack Engineer, Core Messaging and APIs San Francisco, CA

• Contributed to the PHP to Hack and HHVM migration in the messaging webapp, adding static types and moving templates to XHP.

• Built backend support for the Events API so third-party apps could receive event types that were only available on the RTM WebSocket before.

• Shipped backend pieces for threaded messaging, including the thread data model, fanout, and read state tracking.

• Worked on Enterprise Grid data model changes, moving DMs and Group DMs from team shards to org shards with a generic migration framework.

• Helped migrate parts of the web client from jQuery and Handlebars to React, including search results and channel views.

• Worked on the Electron-based desktop client, writing Node.js main-process code for window state, update flow, and OS notifications.

• Improved the Node.js build pipeline for the web client, including Webpack config, Babel upgrades, and faster local rebuild times.

• Added new Web API endpoints for reminders, message edits, and channel management, with matching client SDK updates.

• Worked with the search team to add new filters and ranking signals on top of the Solr-based search service.

• On-call rotation for the messaging tier and the Web API. Slack 05/2013 - 08/2015

Backend Developer, Core Messaging and APIs San Francisco, CA

• Joined as one of the early engineers before the August 2013 beta launch and helped get core messaging endpoints production ready.

• Built Web API endpoints in PHP for messages, channels, direct messages, and presence, including the first version of message edit and delete.

• Designed MySQL schemas sharded by team ID for message history, stars, and pins.

• Wrote endpoints and worker jobs for file uploads, snippets, and file sharing, storing files in S3.

• Built the first version of incoming and outgoing webhooks and the slash commands API, which became the base for the early integrations ecosystem.

• Wrote PHP and MySQL glue that fed the Solr search index for messages and files.

• Worked with the Java channel server team on the handoff between the PHP webapp and real-time message fanout.

• Wrote internal Node.js and Python tooling for log analysis, deploy scripts, and on-call alerts.

• On-call rotation for the API tier from beta launch through the early scaling years. EDUCATION

University of Illinois Urbana-Champaign 08/2009 - 05/2013 Bachelor of Science in Computer Science

Contact this candidate