Sergio Hernández

Software Engineer

I design, build, and run software for a living — .NET on the back end, and front ends in ASP.NET MVC, .NET MAUI, or React, depending on what the product needs. The projects below span that range: web apps built on React, a GraphQL microservice platform, and a mobile sample on .NET MAUI. This site is a small collection of things I have built on my own time, because I think the best way to show work is to let people see it.

Some of these run live on this server; for the rest, the source is open. Try the live instances, read the code, and if something interests you, it's yours to use.

Projects

Compendio

Live demo

A self-hosted, files-first knowledge base for small and medium organizations. Every page is a plain Markdown file in a folder you own — open it in VS Code, back it up by copying the folder — with an editor a non-technical person can use, folder-level permissions, full-text search, versioning, optional AES-256 encrypted folders, and an optional AI assistant. One binary, one service, zero external dependencies. Fully bilingual (English and Spanish), AGPL-licensed.

.NET 10 · React 19 · SQLite + FTS5 · single container

About this demo instance Sign in with admin / Compendio-Demo! — yes, the credentials are public on purpose.
  • Anyone can read and edit, so treat everything in it as public. Please don't put real or personal information in it.
  • The whole instance is restored to its default state every Monday, so any changes — content, users, even a changed admin password — are wiped weekly.
  • If someone left it in a mess or changed the password, come back after Monday's reset.

Everdue

Live demo

An operational accountability platform for small and medium non-software businesses. The name encodes the model: a responsibility is ever due — it never finishes, it comes due again every period, and whether it happened goes on the record. Missed periods are recorded as missed instead of silently rolled forward, and fixed reports answer what a manager actually asks: which responsibilities are chronically missed, who is blocked rather than unreliable, and where waiting time goes. AGPL-licensed.

.NET 10 · React 19 · SQLite / PostgreSQL · single container

About this demo instance Sign in as the admin ana@demo.everdue.app or the regular member john@demo.everdue.app — password EverdueDemo2026! for both. The credentials are public on purpose, and the instance comes pre-loaded with six months of realistic (fake) history so the reports have something to say.
  • Anyone can sign in and change things, so treat everything in it as public. Please don't put real or personal information in it.
  • The instance is wiped and reseeded every Monday, so any changes are temporary by design.

TrackHub

Source only

A vendor-neutral fleet-tracking platform for organizations that inherited their GPS hardware from several suppliers, each with its own portal and login. TrackHub connects to every provider through a pluggable provider model, normalizes what they report, and gives the whole fleet one live map, one set of geofences, one trip board, one report catalog and one permission model. Open source, self-hosted, multi-tenant and bilingual (English and Spanish).

.NET 10 · React 19 · GraphQL microservices · PostgreSQL + PostGIS

MAUI Location Service

Source only

A .NET MAUI sample app that demonstrates how to obtain periodic GPS location updates and keep delivering them while the app runs in the foreground and — with platform support and the proper permissions — in the background. It includes permission-consent helpers for iOS and Android, a configurable background polling loop, and lightweight messaging to push updates to the UI, with platform-specific service implementations for each OS.

.NET MAUI (.NET 10) · iOS + Android · CoreLocation · foreground/background services