Hosein Hayati

Senior .NET Backend Engineer | Wallets, Ledgers & Insurance Core Systems

About

I work on systems where mistakes are expensive. For seven years I have worked on wallets, ledgers and insurance platforms — the kind of system where a rounding error is a real person's real money.

As the sole developer, I took Saman Insurance's digital wallet from a half-finished codebase to production, where it processed over 200 billion Tomans in roughly two years. I built the ledger model, concurrency control, idempotency across payment-gateway callbacks, automated nightly reconciliation and the audit trail.

Architecture, to me, is not a diagram — it is what decides how bad your worst on-call night gets. I work with Clean Architecture, DDD and CQRS because in practice they keep the cost of change low. Open to remote opportunities.

Technical Skills

.NETC#ASP.NET CoreDockerSQL ServerRedisEF CoreDapperClean ArchitectureDDDCQRSMicroservices
.NET EcosystemASP.NET Core, DI, Middleware, Filters, Background Services, Configuration, Options Pattern
APIRESTful API, Swagger / OpenAPI
ORM & DatabaseEF Core (Code First, Migration, AsNoTracking), Dapper, T-SQL
SQL PerformanceTuning, Indexing, Execution Plan, SQL Server Profiler
NoSQLRedis (distributed cache), MongoDB (familiar)
LoggingSerilog, ELK Stack (Kibana), Seq, Grafana, Custom Metrics
ReportingStimulsoft (design, data binding, export)
ArchitectureClean Architecture, DDD, CQRS, Repository, Unit of Work, Mediator, Event-Driven
DevOpsGit, Docker (Dockerfile, Compose), CI/CD (familiar)
FrontendJavaScript, React (familiar), Blazor
AI ToolsClaude, GitHub Copilot — daily workflow
LanguageEnglish – Intermediate (technical docs)

Experience

Senior Backend Developer & System Design — Saman Insurance

Jul 2023 – Present

Tehran, Iran

Digital Wallet System (Saman Insurance App)

  • Ledger as the single source of truth — every balance a user sees is reconstructable from recorded transactions, not from a cached column.
  • Money as a value object (amount + currency + rules) instead of a bare decimal, so cross-currency and negative-amount errors fail loudly at the domain boundary.
  • Idempotency across payment-gateway callbacks and user retries — duplicate callbacks and double-clicks no longer create duplicate money.
  • Concurrency control on balance mutation, eliminating a race condition that duplicated funds in early staging.
  • Automated nightly reconciliation, written after one manual mismatch investigation cost three days.
  • Structured logging with Serilog + ELK; transaction monitoring dashboard for the operations team, plus pattern-based detection for abnormal transaction bursts.
  • Two wallet types (credit and cash) with independent business rules; gateway deposits, referral credit, withdrawal, P2P transfer. Payment-gateway integration built as a separate service with explicit failure paths.
  • Absorbed 10x growth in transaction volume via query tuning, Redis caching and background jobs; onboarded the six-engineer team that later took the system over.

Insurance Systems Contribution

  • Gold Unit-Link (Microservices, DDD, Event-Driven, .NET 6): development & maintenance of event-based insurance services
  • Darmanat (ASP.NET MVC, ADO.NET, .NET 4.5): new features, Custom Metrics, Grafana dashboards
ASP.NET CoreEF CoreSQL ServerRedisSerilogELK StackGrafana

.NET Developer — Mehrsepand

Dec 2021 – Jul 2023

Tehran, Iran

  • Developed and maintained internal banking software with ASP.NET Core Web API
  • Applied Domain-Driven Design (DDD) for effective software layering
  • Used Entity Framework and Dapper for efficient database communication
  • Integrated external services via Flurl; used Stimulsoft for reporting
ASP.NET CoreEFDapperDDDFlurlStimulsoft

Full-Stack Web Developer — Saipa

Sep 2020 – Nov 2021

Tehran, Iran

  • Led migration of internal system from Oracle Forms to modern ASP.NET Core + React
  • Used Kendo UI for front-end and Stimulsoft for reporting
ASP.NET CoreReactKendo UIStimulsoft

Projects

Pishgamit — Tech News & Learning Platform

Founder and sole engineer since 2017 — the longest-running system I own. 4,000+ articles, peak 157K monthly visits, rebuilt from ASP.NET MVC onto .NET 8.

  • Full ownership: SQL Server, IIS, VPS, deployment, monitoring and SEO.
  • Recovered from a Google penalty by removing ~60% of low-quality content and rebuilding the taxonomy (11,000 tags down to a usable structure).

Digital Wallet — Microservices (Open Source)

Open-source digital wallet with modern architecture

  • ASP.NET Core 8 + Clean Architecture + CQRS + Event-Driven + Docker Compose

Soft Skills

  • Accountable and committed to deadlines
  • Strong requirements analysis
  • Experience under high pressure
  • Familiar with Scrum/Agile
  • Onboarding & technical documentation
  • Remote-work capable
  • Continuous learning mindset
  • Fast learner of unfamiliar systems

Education

Bachelor’s Degree – Software Engineering Technology

Islamic Azad University, Mahshahr Branch | 2013 – 2017 | GPA: 15/20

Contact