diff --git a/gshmm.go b/gshmm.go
index 8a0360d..ec4e52f 100644
--- a/gshmm.go
+++ b/gshmm.go
@@ -16,6 +16,12 @@ import (
 	"github.com/sahilm/fuzzy"
 )
 
+// filenameFilterMode searches by PDF file name.
+const filenameFilterMode = "filename"
+
+// contentFilterMode searches by PDF contents.
+const contentFilterMode = "content"
+
 // help is the command-line interface help output.
 const help = `go-sh-manymanuals: TODO
 
@@ -67,6 +73,8 @@ type model struct {
 	filteredDatasheets []string    // Filtered view on all datasheets
 
 	datasheetViewport viewport.Model // Viewport for the PDF content
+
+	filterMode string // The filtering mode ("filename", "content")
 }
 
 // datasheetFromName retrieves a datasheet via a name.
@@ -79,6 +87,15 @@ func (m model) datasheetFromName(name string) string {
 	return ""
 }
 
+// toggleFilterMode toggles the filter mode.
+func (m *model) toggleFilterMode() {
+	if m.filterMode == filenameFilterMode {
+		m.filterMode = contentFilterMode
+	} else {
+		m.filterMode = filenameFilterMode
+	}
+}
+
 // datasheet represents a datasheet on disk.
 type datasheet struct {
 	filename string // The name of the file
@@ -132,6 +149,7 @@ func initialModel() model {
 		datasheetNames:     datasheetNames,
 		filteredDatasheets: datasheetNames,
 		datasheetViewport:  viewp,
+		filterMode:         filenameFilterMode,
 	}
 
 	return m
@@ -182,6 +200,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		switch msg.String() {
 		case "ctrl+c":
 			return m, tea.Quit
+		case "tab":
+			m.toggleFilterMode()
 		}
 	}
 
@@ -208,6 +228,18 @@ func (m model) View() string {
 
 	body.WriteString("\n" + m.input.View())
 
+	mode := "filter: "
+	if m.filterMode == filenameFilterMode {
+		mode += "filename"
+	} else {
+		// TODO make this mode actually work once we figure out bleve
+		mode += "content (FIXME)"
+	}
+	body.WriteString("\n" + mode)
+
+	help := "[ctrl-c]: quit | [tab]: filter mode"
+	body.WriteString("\n" + help)
+
 	return body.String()
 }