diff --git a/invivos/app.R b/invivos/app.R
new file mode 100644
index 0000000..f43b8a5
--- /dev/null
+++ b/invivos/app.R
@@ -0,0 +1,52 @@
+library(shiny)
+
+# Define UI for application
+ui <- fluidPage(
+   
+   #Navbar
+   navbarPage("Seguimiento in vivos",
+              tabPanel("Diseño",
+                sidebarPanel(
+                  fileInput(inputId = "file_sizes", label = "Hoja de tamaños", multiple = F),
+                  sliderInput("ncages", "Cajas", min=1, max=10, value=1),
+                  downloadButton("downloadData", "Descargar Excel")
+                  )
+              ),
+              tabPanel("Análisis")
+              )
+   
+   )
+
+# Define server logic required to draw a histogram
+server <- function(input, output) {
+  output$downloadData <- downloadHandler(
+    
+    filename = function() {
+      paste("invivo", ".xlsx", sep="")
+    },
+    content = function(file){
+      ncages<-input$ncages
+      nrat_cage<-5
+      id_tumors<-c("L","R")
+      timepoint<-c(7,10,13,16,19,22,25)
+      
+      
+      template<-expand.grid(LETTERS[1:ncages], 1:5, id_tumors, timepoint)
+      colnames(template)<-c("Cage", "ID animal", "ID tumor", "Timepoint")
+      template<-template[order(template$Timepoint, template$Cage, template$`ID animal`),]
+      template["Group"]<-""
+      template<-rbind(template, template, template)
+      template<-template[order(template$Timepoint, template$Cage, template$`ID animal`, template$`ID tumor`),]
+      template["TS"]<-rep(c("TS-Length", "TS-Width", "TS-Deep"), nrow(template)/3)
+      dtemplate<-dcast(template, Cage+`ID animal`+`ID tumor`+Group+TS~Timepoint)
+      dtemplate[,6:ncol(dtemplate)]<-""
+      
+      write.xlsx(dtemplate,file)
+    }
+  )
+   
+}
+
+# Run the application 
+shinyApp(ui = ui, server = server)
+