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stefan matić

Senior Full Stack Engineer · CTO & Co-Founder of DEVLEGION

I build the whole system, and keep it running.

I'm a full-stack engineer and CTO of DEVLEGION, based in Niš. For seven years I've built production software end to end, from data models and event-driven services to the React interfaces on top. I care about systems that keep working once real users arrive.

Book a 30-min callSee case studies
  • 7 yrs in production
  • 20+ products
  • 0 regressions on a live migration
Portrait of Stefan Matić
How a request travels through a system I buildFive layers: interface, gateway, services, queue and data. Select a layer or send a request to see what each one does.InterfaceReact · Next.jsGatewayApigee · AuthServicesNestJS · gRPCQueueBullMQ · RedisDataPostgres · Mongo↳ hover or tab through the layers
requests served: 0

Press "Send a request". Watch it travel through every layer I build.

Plate 00 · How I buildNiš · CET
Shipped for teams atHostelworldCommonwealth Charter AcademyStatsPerformSimwave Academy
Work

Selected work

All 20+ projects →
Hostelworld: system diagramA booking platform used around the world was running on ageing code. I helped move it onto six modern codebases while guests kept booking, then built what came next: sign-in at the gateway, AI features and a paid subscription.LEGACYExpress · MariaDB6+ NX MONOREPOSNestJSGATEWAYApigee · authLINKUPS APPVue · PlaywrightDATAMongo · Firestore · RedisSOCIAL PASSGoogle Play
Plate 01 · HostelworldBefore → after
Plate 01 · Travel

Hostelworld

A booking platform used around the world was running on ageing code. I helped move it onto six modern codebases while guests kept booking, then built what came next: sign-in at the gateway, AI features and a paid subscription.

0 regressions on live traffic

NestJSNxTypeScriptExpressMongoDB
Read the case study →
edio: system diagramA US online school with 20,000+ students is rebuilding its platform. I help ship version 3, rewriting old features and building new ones side by side, while the current version keeps working for students, teachers and parents.SHARED LIBRARIESReact · Git submodulesEXAMScreate · takeGRADINGgrades · reviewSTUDENTSmanagementPROGRESStracking · feedback
Plate 02 · edioVersion 3
Plate 02 · Education (US K–12)

edio

A US online school with 20,000+ students is rebuilding its platform. I help ship version 3, rewriting old features and building new ones side by side, while the current version keeps working for students, teachers and parents.

One library behind 20,000+ learners

ReactTypeScriptTanStack QueryTailwind CSSDaisyUI
Read the case study →
Atlas Sports Analytics: system diagramLive sports data arrives messy and fast. I've worked across the whole pipeline, from the service that collects raw StatsPerform data to the app fans use, so live scores and stats reach the screen accurately.STATSPERFORMraw dataPROVIDERNestJS · CQRSCONSUMERgRPC · NestJSDATAMongoDBBFFNestJS · CQRSFRONTENDAngular · RxJS
Plate 03 · Atlas Sports AnalyticsReal-time pipeline
Plate 03 · Sports analytics

Atlas Sports Analytics

Live sports data arrives messy and fast. I've worked across the whole pipeline, from the service that collects raw StatsPerform data to the app fans use, so live scores and stats reach the screen accurately.

Predictable latency under sustained load

NestJSCQRSTypeScriptgRPCRxJS
Read the case study →
Process

How I work

  1. 01

    Discover

    We talk about the problem before the tech. You get a clear estimate and a plan you can check.

  2. 02

    Design the system

    I sketch the whole system first: screens, services and data. You sign off before we build.

  3. 03

    Build & test

    Working releases you can click through every week. Automated tests guard every change.

  4. 04

    Ship & stay

    Launch through an automated pipeline. I stay on after launch to fix, tune and grow it.

Engagements

Ways to work together

For a defined product

Project

For: An MVP, a rebuild or a migration with a clear goal.

How: Scoped plan and estimate, weekly releases you can click through.

Book a call →
Available from October 2026

Contract, in your team

For: Teams that need a senior full-stack engineer now, without a long hiring process.

How: Monthly rate, long-term. I work in your tools, rituals and codebase, overlapping with US and EU hours.

Discuss a contract
For permanent hires

Full-time

For: Companies hiring a senior engineer or tech lead.

How: Remote from Niš (CET). The full CV has every project.

Download CV →
7 years

shipping production software

since 09.2019

20+

products shipped

20,000+

learners on a platform whose component library I co-maintain

0

regressions on a live legacy migration for a global booking platform

Stack

What I work with

Grouped by the layers in the diagram above
InterfaceWhat people click
ReactNext.jsTypeScriptAngularVueTailwindshadcn/uiTanStack
API & gatewayWho gets in, and how
RESTGraphQLgRPCWebSocketsJWT / OAuthApigee
ServicesWhere the work happens
Node.jsNestJSExpressNx monoreposMicroservices
Queue & eventsSlow work, in order
BullMQRedisRxJSEvent-driven design
DataSaved safely, found fast
PostgreSQLMongoDBFirestoreMySQLPrismaTypeORM
Cloud & qualityShips safely, stays up
GCPAWSDockerCI/CDPlaywrightJestCucumber
Leading teamsThe human layer
ArchitectureCode review standardsHiringMentoringEstimation
Have a project?

Let's build the whole thing properly.

An MVP, a rebuild, or a system that has to survive launch day. Tell me what you're building in a 30-minute call.

Book a 30-min callmaticstefan1996@gmail.com
Need an engineer on your team?

Senior full-stack, remote, CET.

Available as a long-term contractor on a monthly rate, embedded in your team, or full-time. Seven years across React, Node and the cloud, plus CTO experience.

Discuss a contractDownload CVLinkedIn →