Nahid Babu.
Senior Full-Stack & Platform Engineer
Architecting mission-critical US healthcare compliance platforms (.NET 10, Python, GCP) and multi-industry AI SaaS systems — based in Geneva, Switzerland.
About & Impact.
I'm a Senior Full-Stack & Platform Engineer specializing in enterprise healthcare compliance systems and multi-industry SaaS platforms. Over the past three years, I have been the single largest contributor (~30% of all commits, 940+ commits, 370+ tickets) to WellSky's Electronic Visit Verification (EVV) platform — a federally mandated healthcare compliance system that verifies home-health visits across 45+ US state-and-vendor combinations.
My ownership spans every layer of the stack: designing multi-state vendor integrations across ~147k lines of Python, building operator workflows in the Next.js/React Transaction Manager, managing 5 GCP environments across 136 Terraform commits, and resolving P0 production incidents. Currently, I am building the platform's next-generation, spec-driven .NET 10 successor (~68k lines of C#, ~2,000 xUnit tests) alongside the live system using a strangler-fig migration pattern.
Alongside my enterprise healthcare work, I founded and architected Dekhval — an AI-powered multi-tenant ERP and operations platform (~396 commits, 37 modules, 5,028-line Prisma PostgreSQL schema) serving healthcare, pharmacy, retail, agriculture, and service businesses. Having previously built European GDPR compliance and real-time streaming systems here in Geneva, I am now based in Geneva, Switzerland and excited to contribute to innovative engineering teams across the region.
Platform Contributions at a Glance
EVV Next-Generation Platform (.NET 10)
~68k LOC C#Core Architect & Engineer — Current Focus
8 production projects · ~2,000 xUnit v3 tests
Spec-driven strangler-fig successor: single typed contract driving validation, OpenAPI/docs, Roslyn C# codegen, golden-locked vendor transformers, and a 6-RID self-updating CLI.
EVV Core Compliance Backend (Python)
738 commits#1 Contributor (~30% of all commits)
295 tickets · ~147k LOC Python · 3,557 unit tests
Delivered across all 14 vendor aggregator families and 25+ US states, including building DCI Oregon end-to-end from scratch and full state onboardings for MA, KS, NM, NY, and UT.
EVV Platform Infrastructure (Terraform IaC)
136 commitsPrimary Vendor-Onboarding Engineer
41 tickets · 5 GCP environments (dev/qa/stage/prod/DR)
Managed 6 Cloud Run services, 20+ Cloud Scheduler crons, 60+ Firestore composite indexes, 35+ secrets, dual API Gateways for zero-downtime maintenance, and state drift recovery.
EVV Transaction Manager (Next.js UI)
73 commitsFeature Owner
35 tickets · React 18 · Ant Design 5 · GraphQL + REST
Built caregiver/patient requeue workflows, bulk reason-code operations, cursor-backed numbered pagination, Live-In visit views, and hardened CI/CD stage/prod gates.
EVV Transaction Audit-Trail API (FastAPI)
P0 FixP0 Incident Responder & Contributor
Python 3.13 · FastAPI · Firestore + Cloud Storage
Diagnosed and resolved a platform-wide P0 compliance report outage caused by an unpinned transitive gRPC breaking change across all environments.
Dekhval ERP & Marketing Platform (SaaS)
417 commitsFounder & Lead Architect
37 ERP modules · 5,028-line Prisma schema · EN/BN i18n
Built multi-tenant Healthcare, Pharmacy FEFO POS, AI WhatsApp bots, Postiz Social Media Gateway, Project Management, Stripe billing, and self-healing Docker/Coolify deployments.
Core Engineering Competencies
Platform Modernization
Strangler-fig migration onto a spec-driven .NET 10 platform with Roslyn-enforced boundaries and a 6-RID self-updating CLI.
Multi-Vendor Backend Engineering
Extensible integration frameworks spanning 14 aggregator families, 25+ US states, and REST/SOAP/SFTP protocols.
Distributed & Event-Driven Systems
At-least-once Pub/Sub & Eventarc pipelines, dead-letter handling, Redis cross-instance coordination, and 20+ batch crons.
Compliance & Data Integrity
Eliminating silent cursor drift, enforcing Decimal(8,6) precision, FEFO batch accounting, and HIPAA/PII minimization.
Cloud Infrastructure (Terraform IaC)
5-environment GCP management (dev/qa/stage/prod/DR), 60+ composite indexes, state drift recovery, and zero-downtime gateways.
Performance & Cost Engineering
O(1) cursor pagination over Firestore, redundant write elimination, and direct ID authorization lookups.
Experience.
WellSky
Senior Software Engineer — EVV Platform & Next-Gen Architecture
Jul 2023 — Present · Remote (US Healthcare Compliance)
Single largest contributor (~30% of all commits; 940+ commits and 370+ Jira tickets) across the federally mandated Electronic Visit Verification (EVV) compliance platform, and core engineer on its spec-driven .NET 10 successor.
- ▹Architecting the EVV Next-Generation Platform in C# / .NET 10 (~68k LOC, 8 production projects, ~2,000 xUnit v3 tests) using a strangler-fig migration alongside the legacy Python API, where a single typed spec drives validation, JSON Schema, Markdown docs, Roslyn codegen, and byte-deterministic payload emission.
- ▹Enforced strict platform-to-vendor boundaries via assembly references and Roslyn-parsed architecture tests, paired with a cross-platform self-updating CLI (`evv`) distributed across 6 runtime identifiers (Windows/macOS/Linux, x64/arm64).
- ▹Engineered features and state compliance across all 14 vendor aggregator families in the ~147k-line Python backend (Sandata, HHAeXchange, Tellus/Netsmart, CareBridge, AHCCCS, AuthentiCare, DCI, Therap, eMedNY, UEVV), including building DCI Oregon end-to-end from scratch (~1,970 lines).
- ▹Led multi-environment GCP infrastructure provisioning across 5 environments (dev, QA, stage, prod, DR) with 136 Terraform commits — managing 6 Cloud Run services, 20+ Cloud Scheduler crons, 60+ Firestore composite indexes, 35+ secrets, and zero-downtime API Gateway maintenance switching.
- ▹Delivered full-stack workflows in the Next.js / React 18 / GraphQL Transaction Manager (bulk reason codes, caregiver/patient requeue, O(1) cursor-backed page-numbered pagination, Live-In visit management) and resolved a P0 platform-wide audit-trail outage.
Dekhval
Founder & Lead Platform Architect
2023 — Present · Remote / Dhaka, Bangladesh
Designed and built an AI-powered multi-tenant business operations ERP (37 modules, ~396 commits) and bilingual marketing platform serving Healthcare, Agriculture, Retail, and Services SMEs.
- ▹Architected a 37-module multi-tenant SaaS ERP on Next.js 16, React 19, TypeScript, and a 5,028-line Prisma PostgreSQL schema with strict organization-level data isolation.
- ▹Built comprehensive Healthcare & Pharmacy modules including doctors, appointments, prescriptions, surgeries, medical camps, optical catalogs, and FEFO (First Expired, First Out) batch-tracked pharmacy POS inventory.
- ▹Integrated multi-provider AI capabilities (Claude API, OpenAI, WhatsApp bots, natural language queries with human-in-the-loop approval workflows) and a multi-platform Social Media Scheduler via Postiz and Facebook Graph API.
- ▹Engineered self-healing production deployments on Docker/Coolify with automatic Prisma P3009 failed-migration recovery, idempotent SQL migrations, exponential-backoff concurrency guards, and lazy SDK initialization.
- ▹Created the bilingual (English + Bangla) marketing site (`dekhval.com`) featuring 9 industry-specific landing pages, MDX blog, and interactive workflow visualizations.
Uberry
Software Engineer
2020 — 2022 · Geneva, Switzerland
Developed European privacy compliance platforms and real-time asynchronous data streaming systems in Geneva.
- ▹Developed 'Priveo' — a GDPR compliance management platform enabling European businesses to automate data subject requests, consent workflows, and privacy audits.
- ▹Built asynchronous WebSocket architectures for real-time dynamic data processing and low-latency notifications.
- ▹Designed high-performance relational and caching layers with PostgreSQL and Redis.
- ▹Collaborated across cross-functional European engineering and product teams in an agile environment.
Earlier Engineering Roles
Full-Stack Software Engineer
2019 — 2020 · Dhaka, Bangladesh
Built full-stack web applications and RESTful APIs for high-concurrency client platforms.
- ▹Built full-stack web applications using Django REST Framework and React.
- ▹Designed and optimized relational database schemas with PostgreSQL and MySQL.
- ▹Implemented RESTful APIs serving thousands of concurrent users with automated testing and CI/CD pipelines.
Production Systems & Architecture.
End-to-end systems I have architected, built, and operated in production — spanning a spec-driven .NET 10 healthcare compliance platform, a 14-vendor Python compliance engine across 25+ US states, a 5-environment GCP Terraform footprint, and a 37-module multi-tenant SaaS ERP.
EVV Next-Generation Platform — Spec-Driven .NET 10 API, SDK & CLI
Strangler-Fig Successor Platform · Local-First API, Contract SDK & Cross-Platform CLI
The spec-driven .NET 10 successor to the legacy Python EVV core backend. Built alongside the live system using a strangler-fig pattern with a transparent reverse proxy so clients can adopt a single surface early, while doubling as a unified 'backend for QA'.
- ▹Spec as the single source of truth: the EVV payload contract is authored once as a typed spec value over an order-preserving typed value-tree IR. Every artifact is a pure interpreter of it — JSON validation, JSON Schema, Markdown docs, deterministic payload emission, Roslyn C# code generation, and structural spec diffs.
- ▹Event-driven ingest spine (`validate → persist → publish`) with an at-least-once, ack-after-publish background consumer that composes and submits vendor-specific payloads (400 malformed / 422 contract-invalid / 201 created / 503 store or publish failure).
- ▹Lane-agnostic storage and messaging seams: the exact same ingest flow runs in-memory, against Dockerized Firestore + Pub/Sub emulators, or on GCP with zero cloud credentials required locally.
- ▹Compiler-enforced vendor boundary: vendor assemblies reference the platform, never the reverse (making a platform→vendor import a build error), backed by Roslyn-parsed architecture tests forbidding vendor names in identifiers/literals and enforcing zero `global using`.
- ▹Result-style error handling via closed discriminated union C# records (`Lookup<T>`, `SaveOutcome`, `ClaimOutcome`) with exhaustive pattern matching, plus explicit layered config loading (Code Defaults → Secret Manager → File → Env Vars).
- ▹Security model with SHA-256 hashed Personal Access Tokens (shown once, rotated via revoke-and-remint), BFF cookie flow with OIDC, and a write-protected cloud credential store.
- ▹Built the `evv` CLI with a pure, IO-free scenario runner streaming typed events for HTTP steps, variable interpolation, and EVV steps to Console, Log, and NDJSON renderers with masked history snapshots.
- ▹Implemented `evv superset` subcommands (`emit`, `validate`, `schema`, `docs`, `codegen`, `diff`) directly interpreting the contract spec.
- ▹Packaged self-contained CLI binaries for 6 runtime identifiers (Windows/macOS/Linux, x64/arm64) with `gh` bootstrap installation, `evv update` self-updating release channels, and `evv install qa` for AI-assisted QA workspaces.
- ▹Shipped contract-first server-side filter/sort/page read endpoints with full wire contract and auth gates so sibling transaction-manager teams can integrate in parallel.
- ▹CalVer commit-deterministic releases (`vYYYY.MM.DD-<sha>`) where CLI binaries and API container images are cut from the exact same commit.
- ▹Non-vacuous CI merge gate running against Dockerized Firestore & Pub/Sub emulators that asserts every test suite reported results and emulator-gated tests actually executed.
- ▹Golden-locked vendor transformers and spec outputs, hand-rolled fakes instead of mocking frameworks, and process-wide invariant globalization.
EVV Core Backend — Multi-Vendor Healthcare Compliance Engine
Enterprise Medicaid Visit Verification API, Batch Workers & Aggregator Pipelines
Enterprise compliance engine that receives home-health visit, caregiver, patient, and authorization records, validates them against per-state Medicaid rules, transmits payloads to state aggregators over REST, SOAP, and SFTP, and reconciles acknowledgements and billing statuses.
Dekhval ERP — 37-Module Multi-Industry SaaS Platform
Multi-Tenant Enterprise Operations Platform with Healthcare, POS & AI Workflows
Comprehensive multi-tenant SaaS ERP platform serving Healthcare, Agriculture, Retail, and Services industries. Evolved from an agricultural seed production system into a 37-module enterprise platform with integrated AI assistants, hospital/pharmacy management, and Stripe billing.
EVV Platform Infrastructure — Multi-Environment GCP Terraform (IaC)
Cloud-Native Healthcare Infrastructure Across Dev, QA, Stage, Prod & DR
Infrastructure-as-Code monorepo managing the complete Google Cloud footprint for the EVV compliance platform across 5 isolated environments (dev, QA, stage, prod, and Disaster Recovery).
EVV Transaction Manager — Enterprise Web Console
Operational Healthcare Compliance UI for Home-Health Agencies
The operational web console where home-health agency staff review visit verifications, diagnose state aggregator rejections, apply bulk reason codes, manage caregivers and patients, and oversee Live-In care relationships.
EVV Transaction Audit-Trail API
Regulatory Document History & Dynamic Compliance Reporting Microservice
FastAPI microservice exposing field-level version history for every EVV transaction document by reconciling versioned Cloud Storage snapshots against live Firestore state, paired with an asynchronous Pub/Sub compliance report generator.
Dekhval.com — Internationalized AI Operations Platform
Bilingual (English + Bangla) Product Marketing, Interactive Flows & Industry Solutions
Internationalized marketing and product showcase platform for Dekhval's WhatsApp-first AI operations partner, tailored for SMEs across 9 industry verticals in English and Bangla.
Engineering Challenges & Problem-Solving.
28 real-world production incidents, silent compliance defects, multi-state integration edge cases, and architectural bottlenecks I diagnosed and resolved across WellSky EVV and Dekhval ERP — along with the engineering principles that guide my work.
Production Report Generation Broken — gRPC Transitive Dependency Conflict
All compliance report generation across every environment suddenly stopped working. The FastAPI audit service threw `'_UnaryStreamMultiCallable' object has no attribute '_retry'` on every Firestore `query.stream()` call, blocking healthcare agencies from pulling federally mandated audit reports.
An unpinned `google-cloud-firestore` dependency in `requirements.txt` allowed a container rebuild to resolve a newer `grpcio` release that removed the internal `_retry` attribute still expected by the Firestore SDK.
- ▹Recognized the stack trace bottomed out in vendor internals despite an empty application code diff.
- ▹Bisected the version matrix locally and pinned `grpcio>=1.62.0,<1.71.0` and `google-cloud-firestore>=2.16.0,<3.0.0`.
- ▹Restored report generation across all environments with a surgical 2-line dependency pin.
SFTP Pull Timeouts Blocking CareBridge Visit Processing
Eliminated wasted SFTP connections and prevented pull timeouts across 6 CareBridge states (IA, AR, NC, NJ, TN, WY).
500 Internal Server Errors on Patient & Caregiver Requeue
Unblocked daily EVV submission workflows for agencies correcting patient and caregiver records.
Pagination Cursor Using Wrong Field — Silent Data Skipping
Restored 100% pagination accuracy across thousands of daily compliance records in the Transaction Manager.
Void Claim Lifecycle (`ClaimAction=V`) Across 6 CareBridge States
Enabled automated claim reversals across 6 US states, preventing erroneous Medicaid billing for cancelled home-health visits.
GPS Coordinate Precision Mismatch — HHA Exchange Rejections
Eliminated GPS format rejections for all Minnesota home-health agencies submitting to HHA Exchange.
PII Minimization in State Caregiver Payloads
Enforced strict healthcare data minimization across state boundaries, reducing PII surface area in external transmissions.
Location Type Casing Inheritance Regression Across HHA States
Restored multi-state SFTP compliance while satisfying New York's V5 specification.
7 Engineering & Problem-Solving Principles
Consistent engineering habits forged across 28 production incidents, compliance audits, and platform migrations.
Diagnose Before You Fix
Every fix starts with root-cause analysis, not symptom treatment — whether tracing a `_UnaryStreamMultiCallable` error into unpinned gRPC internals or proving that pagination cursor fields must match the active sort order.
Test What You Fix
Every bug is a test gap. A 1-line variable fix ships with 332 lines of tests; the adjusted-visit-time rule ships with ~1,500 lines; the Utah SOAP integration ships with 1,064 lines. Each test is a contract that the failure won't recur.
Respect the Blast Radius
In a multi-state aggregator architecture where 14 vendor families and 25+ states share base classes, a 'simple' base change can break 5 states. I trace the full inheritance tree and consumer graph before touching shared contracts.
Build Self-Healing Systems
Production systems should recover without 2 AM SSH sessions: Docker entrypoints automatically clear partial Prisma migrations, SFTP workers skip empty runs before connecting, and caregiver pipelines diff payloads before requeuing.
Security & Privacy Are Non-Negotiable
Healthcare data carries HIPAA and 21st Century Cures Act obligations. From stripping unneeded SSNs/NPIs in state payloads to hashing PATs with SHA-256 and closing stored XSS vectors, security is fixed immediately.
Understand the Cost Model
Patterns that are free in SQL can be a financial trap in cloud NoSQL. Replacing Firestore offset scans (O(N) billed reads) with cursor traversal + count metadata prevented a read-cost explosion across 50,000+ record tables.
Make the Right Thing Structural
The best fixes turn a rule people have to remember into one the compiler enforces. In the .NET 10 successor platform, one typed spec drives validation, docs, schema, codegen, and payload emission, and Roslyn tests enforce vendor boundaries at build time.
What Drives My Engineering
Why I care deeply about high-stakes healthcare reliability, root-cause diagnosis, and structural correctness.
The Healthcare Stakes Are Real
Every EVV transaction represents a real caregiver helping a patient at home. When the system fails, agencies can't submit compliance data and caregivers risk delayed pay. Building reliable software here directly protects healthcare workers and patients across the US.
Modernizing a System That Can't Stop
Three years of fixing the legacy Python platform taught me exactly where its defects originate: duplicated contracts across 14 vendors and identifiers overwritten by the pipeline. Building its spec-driven .NET 10 successor via a strangler-fig migration rules out those defect classes by construction — without a risky cutover.
Problem Diagnosis Over Quick Fixes
The most satisfying fixes often end in a small diff after a deep investigation — bisecting transitive gRPC versions, catching an always-truthy `[None, None]` Python list guard, or uncovering silent cursor drift.
Bridging Compliance Precision & SaaS Breadth
Working across US Medicaid compliance (where a single extra space rejects a claim) and a 37-module multi-tenant ERP (spanning pharmacy FEFO inventory, AI bots, and Stripe billing) sharpens both microscopic precision and macro-level system architecture.
Skills.
Languages
Backend & Architecture
Frontend & UI
Cloud & Infrastructure (GCP)
Data, DevOps & Tooling
Testing, Observability & Integrations
Get in Touch.
I'm based in Geneva, Switzerland and open to new opportunities. Whether you have a question or just want to connect, feel free to reach out.
nahidjahid8698@gmail.com
+41 77 943 59 42
linkedin.com/in/nahidbabu
GitHub
github.com/Nahid71