diff --git a/main.go b/main.go
index 339c23f..a923d4c 100644
--- a/main.go
+++ b/main.go
@@ -44,6 +44,8 @@ func main() {
 		errl.Fatalf("repository: %v", err)
 	}
 
+	seedDemoData(repo)
+
 	s := &Server{
 		Cfg:        cfg,
 		initialCfg: cfg,
@@ -79,6 +81,10 @@ func (s *Server) resetLoop(interval time.Duration) {
 		if resetter, ok := s.repo.(interface{ Reset() }); ok {
 			resetter.Reset()
 		}
+
+		// Re-seed demo data after reset
+		seedDemoData(s.repo)
+
 		s.mu.Lock()
 		s.Cfg = s.initialCfg
 		s.resetAt = time.Now().Add(interval)
diff --git a/seed.go b/seed.go
new file mode 100644
index 0000000..14c471e
--- /dev/null
+++ b/seed.go
@@ -0,0 +1,133 @@
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"zeitkort-web/repository"
+)
+
+func seedDemoData(repo repository.Repository) {
+	if resetter, ok := repo.(interface{ Reset() }); ok {
+		resetter.Reset()
+	}
+
+	now := time.Now()
+	loc := now.Location()
+
+	mukki, _ := repo.InsertCompany(repository.Company{
+		Name:         "Mukki",
+		Address:      "Snoppiesgøta 1, FO-100 Tórshavn",
+		ContactEmail: "kontakt@mukki.fo",
+		ContactPhone: "+298 210000",
+		HourlyRate:   850,
+	})
+
+	teltlar, _ := repo.InsertCompany(repository.Company{
+		Name:         "Teldlar og Teldur",
+		Address:      "Teldutrøð 5, FO-100 Tórshavn",
+		ContactEmail: "info@teltlar.fo",
+		ContactPhone: "+298 310000",
+		HourlyRate:   750,
+	})
+
+	sjogvur, _ := repo.InsertCompany(repository.Company{
+		Name:         "Sjógvur.fo",
+		Address:      "Vesturgøta 22, FO-100 Tórshavn",
+		ContactEmail: "heiðri@sjogvur.fo",
+		ContactPhone: "+298 410000",
+		HourlyRate:   650,
+	})
+
+	mukkiAPI, _ := repo.InsertAssignment(repository.Assignment{
+		CompanyID:   mukki.ID,
+		Name:        "Microservices Backend Migration",
+		Description: "Refactoring legacy monolith into Go microservices.",
+		HourlyRate:  850,
+		Status:      "active",
+	})
+	mukkiInfra, _ := repo.InsertAssignment(repository.Assignment{
+		CompanyID:   mukki.ID,
+		Name:        "Kubernetes Cluster Setup",
+		Description: "Deploying K3s cluster.",
+		HourlyRate:  850,
+		Status:      "active",
+	})
+
+	teltlarERP, _ := repo.InsertAssignment(repository.Assignment{
+		CompanyID:   teltlar.ID,
+		Name:        "ERP Integration Module",
+		Description: "REST API bridge between SQL Server and frontend.",
+		HourlyRate:  750,
+		Status:      "active",
+	})
+
+	sjogvurWeb, _ := repo.InsertAssignment(repository.Assignment{
+		CompanyID:   sjogvur.ID,
+		Name:        "Corporate Website Redesign",
+		Description: "Modernizing frontend with Tailwind and static generation.",
+		HourlyRate:  650,
+		Status:      "active",
+	})
+
+	tMukkiAPI, _ := repo.InsertTask(repository.Task{AssignmentID: mukkiAPI.ID, Name: "Design gRPC Protobufs"})
+	tMukkiAPI2, _ := repo.InsertTask(repository.Task{AssignmentID: mukkiAPI.ID, Name: "Implement Auth Middleware"})
+	tMukkiInfra, _ := repo.InsertTask(repository.Task{AssignmentID: mukkiInfra.ID, Name: "Ansible Playbooks"})
+
+	tTeltlar, _ := repo.InsertTask(repository.Task{AssignmentID: teltlarERP.ID, Name: "SQL Stored Procedures"})
+	tTeltlar2, _ := repo.InsertTask(repository.Task{AssignmentID: teltlarERP.ID, Name: "API Endpoints"})
+
+	tSjogvur, _ := repo.InsertTask(repository.Task{AssignmentID: sjogvurWeb.ID, Name: "Design System"})
+	tSjogvur2, _ := repo.InsertTask(repository.Task{AssignmentID: sjogvurWeb.ID, Name: "SEO Optimization"})
+
+	addSession := func(assignID, taskID int64, daysAgo int, hours float64) {
+		start := time.Date(now.Year(), now.Month(), now.Day()-daysAgo, 9, 0, 0, 0, loc)
+		end := start.Add(time.Duration(hours * float64(time.Hour)))
+
+		task, _ := repo.GetTaskByID(taskID)
+		desc := fmt.Sprintf("%d - %s", task.Number, task.Name)
+
+		repo.InsertManualWorkSession(repository.WorkSession{
+			AssignmentID:    assignID,
+			TaskID:          taskID,
+			TaskDescription: desc,
+			StartTime:       start,
+			EndTime:         &end,
+		})
+	}
+
+	addSession(mukkiAPI.ID, tMukkiAPI.ID, 5, 4.5)
+	addSession(mukkiAPI.ID, tMukkiAPI2.ID, 3, 2.0)
+	addSession(mukkiInfra.ID, tMukkiInfra.ID, 1, 6.0)
+
+	addSession(teltlarERP.ID, tTeltlar.ID, 4, 3.5)
+	addSession(teltlarERP.ID, tTeltlar2.ID, 2, 5.0)
+
+	addSession(sjogvurWeb.ID, tSjogvur.ID, 6, 2.5)
+	addSession(sjogvurWeb.ID, tSjogvur2.ID, 0, 1.5)
+
+	runningStart := now.Add(-45 * time.Minute)
+	task, _ := repo.GetTaskByID(tSjogvur2.ID)
+	desc := fmt.Sprintf("%d - %s", task.Number, task.Name)
+
+	runningSession, _ := repo.InsertWorkSession(repository.WorkSession{
+		AssignmentID:    sjogvurWeb.ID,
+		TaskID:          tSjogvur2.ID,
+		TaskDescription: desc,
+		StartTime:       runningStart,
+		EndTime:         nil,
+	})
+
+	if runningSession != nil {
+		updated := repository.WorkSession{
+			ID:              runningSession.ID,
+			AssignmentID:    runningSession.AssignmentID,
+			TaskID:          runningSession.TaskID,
+			TaskDescription: desc,
+			StartTime:       runningSession.StartTime,
+			EndTime:         runningSession.EndTime,
+			DurationMinutes: runningSession.DurationMinutes,
+		}
+		repo.UpdateWorkSession(runningSession.ID, updated)
+	}
+}