Nate Mayer
Healthcare EDI · Eligibility, claims, status and remittance

Claims shouldn't learn payer rules by getting rejected.

15+ years building the EDI and revenue-cycle systems behind U.S. healthcare payments. I helped carry a clearinghouse from early stage to tens of millions of transactions a day, through two acquisitions, then led its integration into a national RCM platform with zero-downtime migrations along the way.

I work on the hard parts of healthcare EDI, from the eligibility check to the remittance. On my own time, I write about what I'm building and learning; the current series is Teaching AI to Read Payer Edits.

15+ yearsbuilding healthcare EDI and clearinghouse systems
Tens of millionsX12 transactions a day on the platform I helped build
10× throughputon 837 claim files, headroom for the platform's growth
Sub-secondCAQH CORE certified eligibility and claim status at millions of requests a day
Writing

Learning out loud

I write up what I'm building and learning as I go, including the parts that didn't work.

All writingSubscribe

Selected work

Systems that carry real claims, at scale, without stopping.

Waystar · 2020–present

Platform integration and handoff

Led the multi-year integration of a clearinghouse platform into Waystar's core RCM platform, moving professional and institutional claim clients while dental remained on the legacy platform. The work included multiple zero-downtime migrations under full production load, followed by a transfer of ownership to a newly formed team.

ResultNo interruption to customer claim submission. A team of four went from no X12 experience to running the platform independently.
eSolutions · 2016–2020

Claims processing built for scale

Re-architected the claims processing pipeline for horizontal scale as transaction volume grew, and rebuilt internal clearinghouse applications for fault tolerance and observability, with activity logging and monitoring across the platform.

ResultClaims turnaround cut from hours to minutes.
ClaimRemedi · 2012–2016

Industry mandates that couldn't pause claims

Led the enterprise migrations from X12 4010 to 5010 and from ICD-9 to ICD-10, both against federal compliance deadlines, while claims kept flowing through the platform.

ResultDeadlines met with uninterrupted claims processing throughout.
ClaimRemedi · 2012–2016

Real-time eligibility and claim status

Built national-scale 270/271 eligibility and 276/277 claim status services, answering in real time instead of in batch, so coverage and claim progress can be checked while the provider is working rather than the next day.

ResultSub-second responses at millions of requests a day, CAQH CORE certified.
Experience

Fifteen years in healthcare claims.

Nate Mayer
2020 – now

Waystar

Software Architect · Staff Software Engineer

Led a multi-year clearinghouse integration into Waystar's RCM platform and was responsible for the claims infrastructure end to end. Contributed to Waystar Recoupment Manager, a launched AI product that matches payer PLB adjustments against paid claims to surface post-payment recoupments.

2016 – 2020

eSolutions

Manager of Application Engineering · Senior Application Engineer

Principal technical owner of the clearinghouse platform. Managed a cross-functional team of six across healthcare EDI and RCM applications.

2010 – 2016

ClaimRemedi

Lead Clearinghouse Engineer · Software Engineer

Directed development of the clearinghouse platform through its highest-growth years. Increased 837 file throughput tenfold and built a hybrid role- and attribute-based access system used across all internal applications.

1999 – 2002

U.S. Army

Cavalry Scout (19D) · Airborne
Skills

Domain depth, plus the engineering to use it.

Healthcare EDI and RCM

ANSI X12 837P / 837I / 837D835 remittance270/271 eligibility276/277 claim status999 / 277CA acknowledgments275 claim attachmentsSNIP validationPayer companion guidesCAQH COREDenial managementCPT / ICD-10Payer connectivityClearinghouse integrations

Engineering

.NET / C#ASP.NET / Web APIWindows servicesIISSQL Server / T-SQLPostgreSQLPythonRabbitMQKafkaDockerSOAP / REST APIsSFTP / PGPPowerShellAzure DevOps / TFSGit / GitHub

Applied AI and leadership

LLM pipeline designPrompt cachingStructured outputsSemantic searchSolution architectureTechnical leadershipKnowledge transferDistributed remote teams
Book club

Eight years. Twenty-eight books.

For eight years, the same small group of engineers has met every few weeks to test each book's advice against the code we actually maintain. Domain-Driven Design gave me the vocabulary for bounded contexts. Generative AI with LangChain started the payer-edit project.

Reading now Generative AI Design Patterns · Lakshmanan, Hapke

Architecture and design

  • Domain-Driven Design · Evans
  • Designing Data-Intensive Applications · Kleppmann
  • Fundamentals of Software Architecture · Richards, Ford
  • Building Evolutionary Architectures · Ford et al.
  • Clean Architecture · Martin
  • A Philosophy of Software Design · Ousterhout
  • Designing Distributed Systems · Burns
  • Principles of Web API Design · Higginbotham
  • System Design Interview · Xu, Lam

Microservices and events

  • Building Microservices · Newman
  • Monolith to Microservices · Newman
  • Practical Microservices · Garofolo
  • Building Event-Driven Microservices · Bellemare

Operations

  • Kubernetes: Up and Running · Burns et al.
  • Observability Engineering · Majors et al.
  • Operating Continuously · Rinaldi et al.

Craft

  • Clean Code · Martin
  • Refactoring · Fowler
  • Test Driven Development · Beck
  • Adaptive Code · McLean Hall
  • Head First Design Patterns · Freeman, Robson
  • A Common-Sense Guide to Data Structures and Algorithms · Wengrow
  • CLR via C# · Richter
  • Practical Guidelines and Best Practices · Balena, Dimauro

AI and LLMs

  • Generative AI with LangChain · Auffarth, Kuligin
  • Hands-On Large Language Models · Alammar, Grootendorst
  • Fundamentals of Artificial Intelligence

Career

  • The Staff Engineer's Path · Reilly

Build sessions

  • fast.ai practical deep learning · 2018
  • Local image generation with FLUX and ComfyUI · 2025