Lead Software Engineer at SalesAi · Chicago

Dan Lewis

I build production AI agents and the platforms underneath them.

LLM-driven SMS and voice agents, workflow engines and public APIs, plus about 13 years of full-stack work across payments, finance and advertising.

Selected work

AI SMS agent

AI SMS agent

Designed, built and owned an AI SMS agent end to end. TCPA consent and do-not-call checks run before any LLM call, and detect-and-regenerate guards catch hallucinated replies.

Voice-agent memory

Cross-call contact memory

Architected cross-call contact memory with tenant-scoped pgvector retrieval. Context is assembled once at call start, so it adds no latency to each turn. The trade-off is that it isn't refreshed mid-call.

Voice platform runtime

Workflow engine and voice runtime

Engineered the workflow engine and voice-agent runtime for a multi-tenant platform. Removed misdispatched calls and concurrency leaks, and made guardrail failures fail safe instead of stalling a live call.

Public API

Public API for AI agents

Led the design and build of a public API for AI agents and workflows, with gateway routing, token exchange, per-credential rate limits, idempotency and revocation.

Experience

2026 – present

Lead Software Engineer · SalesAi

  • Own the SMS agent and the public API, and answer for the workflow engine and voice-agent runtime behaving correctly.
  • Evaluate agent quality with eval sets, regression runs on prompt changes and transcript review.
  • Set technical direction across teams through design reviews and ADRs, and mentor engineers at varying seniority.
2025 – 2026

Senior Software Engineer · Meta

  • Developed REST APIs and data pipelines that let ad agencies publish creator-driven ads at scale, driving $162M in ARR.
  • Designed and built an ML-powered brand classification tool for multi-brand retailers, addressing $300M in revenue and performance gains.
  • Created and led a program to find missed integration opportunities with mid-sized clients, adding $28M in ARR.
2023 – 2025

Senior Software Engineer · Golub Capital

  • Created APIs for data queryability, entitlements and work-item tracking, so non-technical staff could self-serve requests that used to need a ticket.
  • Planned and executed .NET application and database migrations to Azure, cutting hardware costs and improving uptime.
2018 – 2023

Software Engineer · Discover Financial Services

  • Developed APIs connecting ServiceNow with Hazelcast for automated failover and failback, protecting Discover's payment processing system from disruption.
  • Provided SME support on production payment and settlement issues for critical applications.
2013 – 2018

Earlier

  • Freelance: designed and ran theatrical control systems for universities, architecture firms and museums, including a TwinCAT GUI that flew a live performer.
  • Vision2 Systems: built a client-facing full-stack payment processing app for nonprofits and churches, and added Elasticsearch to cut search times.

Skills

AI & LLM

  • LLM applications
  • Conversational & voice agents
  • Tool calling / MCP
  • Guardrails
  • RAG & pgvector
  • Prompt engineering
  • Evals
  • LiveKit
  • OpenAI
  • Claude
  • Gemini

Languages & frameworks

  • Java 21
  • Spring Boot
  • C# / .NET
  • TypeScript
  • Node.js
  • React
  • Next.js
  • Python
  • SQL

Cloud & infrastructure

  • Google Cloud
  • Azure
  • Terraform
  • Docker
  • Kubernetes
  • PostgreSQL
  • Redis
  • Elasticsearch
  • Twilio
  • Auth0
  • Datadog

Leadership

  • Design reviews & ADRs
  • Mentoring
  • Cross-team technical direction
  • Shape Up
  • Client integrations

Education

University of Wisconsin–Madison · BS, Design & Theatre