diff --git a/internal/api/clock.go b/internal/api/clock.go
new file mode 100644
index 0000000..10121be
--- /dev/null
+++ b/internal/api/clock.go
@@ -0,0 +1,78 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+// ClockEventData represents the response data returned from the ServiceTrade clock endpoint.
+type ClockEventData struct {
+	TotalPages     int                `json:"totalPages"`
+	Page           int                `json:"page"`
+	ActivityTime   *ClockActivityMap  `json:"activityTime"`
+	PairedEvents   []ClockPairedEvent `json:"pairedEvents"`
+	UnpairedEvents []ClockEvent       `json:"unpairedEvents"`
+}
+
+// ClockActivityMap captures total elapsed seconds for each activity type.
+type ClockActivityMap struct {
+	Onsite  int64 `json:"onsite"`
+	Offsite int64 `json:"offsite"`
+	Enroute int64 `json:"enroute"`
+	Onbreak int64 `json:"onbreak"`
+}
+
+// ClockPairedEvent represents a paired start/end clock event.
+type ClockPairedEvent struct {
+	ElapsedTime int64      `json:"elapsedTime"`
+	Start       ClockEvent `json:"start"`
+	End         ClockEvent `json:"end"`
+}
+
+// ClockEvent represents an individual clock event.
+type ClockEvent struct {
+	EventTime int64     `json:"eventTime"`
+	EventType string    `json:"eventType"`
+	Activity  string    `json:"activity"`
+	Source    string    `json:"source"`
+	User      ClockUser `json:"user"`
+}
+
+// ClockUser represents a technician associated with a clock event.
+type ClockUser struct {
+	Name  string `json:"name"`
+	Email string `json:"email"`
+}
+
+type clockResponse struct {
+	Data ClockEventData `json:"data"`
+}
+
+// GetJobClockEvents retrieves paired clock events for a given job identifier.
+func (s *Session) GetJobClockEvents(jobID string) (*ClockEventData, error) {
+	endpoint := fmt.Sprintf("/clock?jobId=%s", jobID)
+	resp, err := s.DoRequest(http.MethodGet, endpoint, nil)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("error reading response body: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("API returned error: %s - %s", resp.Status, string(body))
+	}
+
+	var result clockResponse
+	if err := json.Unmarshal(body, &result); err != nil {
+		return nil, fmt.Errorf("error unmarshalling clock response: %w", err)
+	}
+
+	return &result.Data, nil
+}
+
diff --git a/internal/handlers/web/invoice_clock_report.go b/internal/handlers/web/invoice_clock_report.go
new file mode 100644
index 0000000..62f9989
--- /dev/null
+++ b/internal/handlers/web/invoice_clock_report.go
@@ -0,0 +1,348 @@
+package web
+
+import (
+	"bytes"
+	"encoding/csv"
+	"fmt"
+	"net/http"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"marmic/servicetrade-toolbox/internal/api"
+	"marmic/servicetrade-toolbox/internal/middleware"
+)
+
+var invoiceClockReportHeader = []string{
+	"invoice_number",
+	"invoice_id",
+	"job_id",
+	"job_number",
+	"assignment_type",
+	"vendor_name",
+	"tech_names",
+	"enroute_events",
+	"onsite_events",
+	"error",
+}
+
+// InvoiceClockReportHandler processes uploaded CSVs of invoice numbers and returns a clock-event report.
+func InvoiceClockReportHandler(w http.ResponseWriter, r *http.Request) {
+	session, ok := r.Context().Value(middleware.SessionKey).(*api.Session)
+	if !ok {
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	if err := r.ParseMultipartForm(10 << 20); err != nil {
+		http.Error(w, fmt.Sprintf("Unable to parse form: %v", err), http.StatusBadRequest)
+		return
+	}
+
+	file, _, err := r.FormFile("invoiceCsv")
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Error retrieving file: %v", err), http.StatusBadRequest)
+		return
+	}
+	defer file.Close()
+
+	csvReader := csv.NewReader(file)
+	records, err := csvReader.ReadAll()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Error reading CSV file: %v", err), http.StatusBadRequest)
+		return
+	}
+
+	if len(records) == 0 {
+		http.Error(w, "CSV file is empty", http.StatusBadRequest)
+		return
+	}
+
+	invoiceNumbers := extractInvoiceNumbers(records)
+	if len(invoiceNumbers) == 0 {
+		http.Error(w, "No invoice numbers found in CSV", http.StatusBadRequest)
+		return
+	}
+
+	var buffer bytes.Buffer
+	writer := csv.NewWriter(&buffer)
+
+	if err := writer.Write(invoiceClockReportHeader); err != nil {
+		http.Error(w, fmt.Sprintf("Error writing CSV header: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	for _, invoiceNumber := range invoiceNumbers {
+		row := buildInvoiceClockReportRow(session, invoiceNumber)
+		if err := writer.Write(row); err != nil {
+			http.Error(w, fmt.Sprintf("Error writing CSV row: %v", err), http.StatusInternalServerError)
+			return
+		}
+	}
+
+	writer.Flush()
+	if err := writer.Error(); err != nil {
+		http.Error(w, fmt.Sprintf("Error finalizing CSV: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	filename := fmt.Sprintf("invoice-clock-report-%s.csv", time.Now().Format("20060102-150405"))
+	w.Header().Set("Content-Type", "text/csv")
+	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", filename))
+	w.Header().Set("Cache-Control", "no-store")
+	w.Write(buffer.Bytes())
+}
+
+func extractInvoiceNumbers(records [][]string) []string {
+	if len(records) == 0 {
+		return nil
+	}
+
+	headers := make([]string, len(records[0]))
+	for i, header := range records[0] {
+		headers[i] = strings.ToLower(strings.TrimSpace(header))
+	}
+
+	columnIndex := 0
+	hasHeader := false
+	for i, header := range headers {
+		if header == "invoice_number" || header == "invoicenumber" || header == "invoice" {
+			columnIndex = i
+			hasHeader = true
+			break
+		}
+	}
+
+	var numbers []string
+	startRow := 0
+	if hasHeader {
+		startRow = 1
+	}
+	for _, row := range records[startRow:] {
+		if columnIndex >= len(row) {
+			continue
+		}
+		number := strings.TrimSpace(row[columnIndex])
+		if number != "" {
+			numbers = append(numbers, number)
+		}
+	}
+
+	return numbers
+}
+
+func buildInvoiceClockReportRow(session *api.Session, invoiceIdentifier string) []string {
+	row := make([]string, len(invoiceClockReportHeader))
+	row[0] = invoiceIdentifier
+
+	invoice, err := session.GetInvoice(invoiceIdentifier)
+	if err != nil {
+		row[len(row)-1] = fmt.Sprintf("invoice lookup error: %v", err)
+		return row
+	}
+	if invoice == nil {
+		row[len(row)-1] = "invoice not found"
+		return row
+	}
+
+	invoiceID := valueToString(invoice["id"])
+	row[1] = invoiceID
+
+	jobInfo, ok := invoice["job"].(map[string]interface{})
+	if !ok {
+		row[len(row)-1] = "invoice missing job information"
+		return row
+	}
+
+	jobID := valueToString(jobInfo["id"])
+	jobNumber := valueToString(jobInfo["number"])
+	row[2] = jobID
+	row[3] = jobNumber
+
+	var errors []string
+
+	jobDetails, err := session.GetJobDetails(jobID)
+	if err != nil {
+		errors = append(errors, fmt.Sprintf("job details error: %v", err))
+	}
+
+	clockData, err := session.GetJobClockEvents(jobID)
+	if err != nil {
+		errors = append(errors, fmt.Sprintf("clock events error: %v", err))
+	}
+
+	techNames := collectTechNames(jobDetails, clockData)
+
+	vendorName := extractVendorName(jobDetails, invoice)
+	assignmentType := determineAssignmentType(techNames, vendorName)
+
+	row[4] = assignmentType
+	row[5] = vendorName
+	row[6] = strings.Join(techNames, ", ")
+
+	if clockData != nil {
+		row[7] = formatActivityEvents(clockData.PairedEvents, "enroute")
+		row[8] = formatActivityEvents(clockData.PairedEvents, "onsite")
+	}
+
+	if len(errors) > 0 {
+		row[len(row)-1] = strings.Join(errors, "; ")
+	}
+
+	return row
+}
+
+func collectTechNames(jobDetails map[string]interface{}, clockData *api.ClockEventData) []string {
+	seen := map[string]struct{}{}
+
+	if jobDetails != nil {
+		if appointments, ok := jobDetails["appointments"].([]interface{}); ok {
+			for _, appt := range appointments {
+				apptMap, ok := appt.(map[string]interface{})
+				if !ok {
+					continue
+				}
+				if techs, ok := apptMap["techs"].([]interface{}); ok {
+					for _, tech := range techs {
+						if techMap, ok := tech.(map[string]interface{}); ok {
+							name := strings.TrimSpace(valueToString(techMap["name"]))
+							if name != "" {
+								seen[name] = struct{}{}
+							}
+						}
+					}
+				}
+			}
+		}
+		if current, ok := jobDetails["currentAppointment"].(map[string]interface{}); ok {
+			if techs, ok := current["techs"].([]interface{}); ok {
+				for _, tech := range techs {
+					if techMap, ok := tech.(map[string]interface{}); ok {
+						name := strings.TrimSpace(valueToString(techMap["name"]))
+						if name != "" {
+							seen[name] = struct{}{}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	if clockData != nil {
+		for _, event := range clockData.PairedEvents {
+			name := strings.TrimSpace(event.Start.User.Name)
+			if name != "" {
+				seen[name] = struct{}{}
+			}
+			name = strings.TrimSpace(event.End.User.Name)
+			if name != "" {
+				seen[name] = struct{}{}
+			}
+		}
+	}
+
+	if len(seen) == 0 {
+		return nil
+	}
+
+	var names []string
+	for name := range seen {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	return names
+}
+
+func extractVendorName(jobDetails map[string]interface{}, invoice map[string]interface{}) string {
+	if jobDetails != nil {
+		if vendor, ok := jobDetails["vendor"].(map[string]interface{}); ok {
+			if name := strings.TrimSpace(valueToString(vendor["name"])); name != "" {
+				return name
+			}
+		}
+	}
+
+	if vendor, ok := invoice["vendor"].(map[string]interface{}); ok {
+		if name := strings.TrimSpace(valueToString(vendor["name"])); name != "" {
+			return name
+		}
+	}
+
+	return ""
+}
+
+func determineAssignmentType(techNames []string, vendorName string) string {
+	if len(techNames) > 0 {
+		return "Technician"
+	}
+	if vendorName != "" {
+		return "Vendor"
+	}
+	return "Unknown"
+}
+
+func formatActivityEvents(events []api.ClockPairedEvent, activity string) string {
+	var parts []string
+	activityLower := strings.ToLower(activity)
+
+	for _, e := range events {
+		if strings.ToLower(e.Start.Activity) != activityLower {
+			continue
+		}
+
+		tech := strings.TrimSpace(e.Start.User.Name)
+		if tech == "" {
+			tech = "Unknown Tech"
+		}
+
+		start := formatTimestamp(e.Start.EventTime)
+		end := formatTimestamp(e.End.EventTime)
+		var durationText string
+		if e.ElapsedTime > 0 {
+			duration := time.Duration(e.ElapsedTime) * time.Second
+			durationText = duration.String()
+		}
+
+		detail := fmt.Sprintf("%s: %s -> %s", tech, start, end)
+		if durationText != "" {
+			detail = fmt.Sprintf("%s (%s)", detail, durationText)
+		}
+
+		parts = append(parts, detail)
+	}
+
+	return strings.Join(parts, " | ")
+}
+
+func formatTimestamp(epoch int64) string {
+	if epoch == 0 {
+		return ""
+	}
+	return time.Unix(epoch, 0).UTC().Format(time.RFC3339)
+}
+
+func valueToString(value interface{}) string {
+	switch v := value.(type) {
+	case string:
+		return v
+	case fmt.Stringer:
+		return v.String()
+	case float64:
+		return strconv.FormatInt(int64(v), 10)
+	case int64:
+		return strconv.FormatInt(v, 10)
+	case int:
+		return strconv.Itoa(v)
+	default:
+		if v == nil {
+			return ""
+		}
+		return fmt.Sprintf("%v", v)
+	}
+}