diff --git a/cmp/compare.go b/cmp/compare.go
index 580ae20..af2f4d3 100644
--- a/cmp/compare.go
+++ b/cmp/compare.go
@@ -123,7 +123,7 @@ func Diff(x, y interface{}, opts ...Option) string {
 		s.result = diff.Result{} // Reset results
 	}
 
-	r := new(defaultReporter)
+	r := new(DefaultReporter)
 	s.reporters = append(s.reporters, reporter{r})
 	s.compareAny(rootStep(x, y))
 	d := r.String()
diff --git a/cmp/options_test.go b/cmp/options_test.go
index f8066c7..bfc83d7 100644
--- a/cmp/options_test.go
+++ b/cmp/options_test.go
@@ -128,7 +128,7 @@ func TestOptionPanic(t *testing.T) {
 	}, {
 		label:     "FilterPath",
 		fnc:       FilterPath,
-		args:      []interface{}{func(Path) bool { return true }, Reporter(&defaultReporter{})},
+		args:      []interface{}{func(Path) bool { return true }, Reporter(&DefaultReporter{})},
 		wantPanic: "invalid option type",
 	}, {
 		label: "FilterPath",
@@ -137,7 +137,7 @@ func TestOptionPanic(t *testing.T) {
 	}, {
 		label:     "FilterPath",
 		fnc:       FilterPath,
-		args:      []interface{}{func(Path) bool { return true }, Options{Ignore(), Reporter(&defaultReporter{})}},
+		args:      []interface{}{func(Path) bool { return true }, Options{Ignore(), Reporter(&DefaultReporter{})}},
 		wantPanic: "invalid option type",
 	}, {
 		label:     "FilterValues",
@@ -170,7 +170,7 @@ func TestOptionPanic(t *testing.T) {
 	}, {
 		label:     "FilterValues",
 		fnc:       FilterValues,
-		args:      []interface{}{func(int, int) bool { return true }, Reporter(&defaultReporter{})},
+		args:      []interface{}{func(int, int) bool { return true }, Reporter(&DefaultReporter{})},
 		wantPanic: "invalid option type",
 	}, {
 		label: "FilterValues",
@@ -179,7 +179,7 @@ func TestOptionPanic(t *testing.T) {
 	}, {
 		label:     "FilterValues",
 		fnc:       FilterValues,
-		args:      []interface{}{func(int, int) bool { return true }, Options{Ignore(), Reporter(&defaultReporter{})}},
+		args:      []interface{}{func(int, int) bool { return true }, Options{Ignore(), Reporter(&DefaultReporter{})}},
 		wantPanic: "invalid option type",
 	}}
 
diff --git a/cmp/report.go b/cmp/report.go
index aafcb36..ab1eb3f 100644
--- a/cmp/report.go
+++ b/cmp/report.go
@@ -4,10 +4,10 @@
 
 package cmp
 
-// defaultReporter implements the reporter interface.
+// DefaultReporter implements the reporter interface.
 //
 // As Equal serially calls the PushStep, Report, and PopStep methods, the
-// defaultReporter constructs a tree-based representation of the compared value
+// DefaultReporter constructs a tree-based representation of the compared value
 // and the result of each comparison (see valueNode).
 //
 // When the String method is called, the FormatDiff method transforms the
@@ -15,34 +15,35 @@ package cmp
 // of the textual output (see textNode).
 //
 // Lastly, the textNode.String method produces the final report as a string.
-type defaultReporter struct {
-	root *valueNode
-	curr *valueNode
+type DefaultReporter struct {
+	root          *valueNode
+	curr          *valueNode
+	FormatOptions FormatOptions
 }
 
-func (r *defaultReporter) PushStep(ps PathStep) {
+func (r *DefaultReporter) PushStep(ps PathStep) {
 	r.curr = r.curr.PushStep(ps)
 	if r.root == nil {
 		r.root = r.curr
 	}
 }
-func (r *defaultReporter) Report(rs Result) {
+func (r *DefaultReporter) Report(rs Result) {
 	r.curr.Report(rs)
 }
-func (r *defaultReporter) PopStep() {
+func (r *DefaultReporter) PopStep() {
 	r.curr = r.curr.PopStep()
 }
 
 // String provides a full report of the differences detected as a structured
 // literal in pseudo-Go syntax. String may only be called after the entire tree
 // has been traversed.
-func (r *defaultReporter) String() string {
+func (r *DefaultReporter) String() string {
 	assert(r.root != nil && r.curr == nil)
 	if r.root.NumDiff == 0 {
 		return ""
 	}
 	ptrs := new(pointerReferences)
-	text := formatOptions{}.FormatDiff(r.root, ptrs)
+	text := r.FormatOptions.FormatDiff(r.root, ptrs)
 	resolveReferences(text)
 	return text.String()
 }
diff --git a/cmp/report_compare.go b/cmp/report_compare.go
index 9e21809..a44efaa 100644
--- a/cmp/report_compare.go
+++ b/cmp/report_compare.go
@@ -35,7 +35,7 @@ const (
 	autoType
 )
 
-type formatOptions struct {
+type FormatOptions struct {
 	// DiffMode controls the output mode of FormatDiff.
 	//
 	// If diffUnknown,   then produce a diff of the x and y values.
@@ -52,23 +52,23 @@ type formatOptions struct {
 	TypeMode typeMode
 
 	// formatValueOptions are options specific to printing reflect.Values.
-	formatValueOptions
+	FormatValueOptions
 }
 
-func (opts formatOptions) WithDiffMode(d diffMode) formatOptions {
+func (opts FormatOptions) WithDiffMode(d diffMode) FormatOptions {
 	opts.DiffMode = d
 	return opts
 }
-func (opts formatOptions) WithTypeMode(t typeMode) formatOptions {
+func (opts FormatOptions) WithTypeMode(t typeMode) FormatOptions {
 	opts.TypeMode = t
 	return opts
 }
-func (opts formatOptions) WithVerbosity(level int) formatOptions {
+func (opts FormatOptions) WithVerbosity(level int) FormatOptions {
 	opts.VerbosityLevel = level
 	opts.LimitVerbosity = true
 	return opts
 }
-func (opts formatOptions) verbosity() uint {
+func (opts FormatOptions) verbosity() uint {
 	switch {
 	case opts.VerbosityLevel < 0:
 		return 0
@@ -83,7 +83,7 @@ const maxVerbosityPreset = 3
 
 // verbosityPreset modifies the verbosity settings given an index
 // between 0 and maxVerbosityPreset, inclusive.
-func verbosityPreset(opts formatOptions, i int) formatOptions {
+func verbosityPreset(opts FormatOptions, i int) FormatOptions {
 	opts.VerbosityLevel = int(opts.verbosity()) + 2*i
 	if i > 0 {
 		opts.AvoidStringer = true
@@ -97,7 +97,7 @@ func verbosityPreset(opts formatOptions, i int) formatOptions {
 
 // FormatDiff converts a valueNode tree into a textNode tree, where the later
 // is a textual representation of the differences detected in the former.
-func (opts formatOptions) FormatDiff(v *valueNode, ptrs *pointerReferences) (out textNode) {
+func (opts FormatOptions) FormatDiff(v *valueNode, ptrs *pointerReferences) (out textNode) {
 	if opts.DiffMode == diffIdentical {
 		opts = opts.WithVerbosity(1)
 	} else {
@@ -200,7 +200,7 @@ func (opts formatOptions) FormatDiff(v *valueNode, ptrs *pointerReferences) (out
 	}
 }
 
-func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind, ptrs *pointerReferences) textNode {
+func (opts FormatOptions) formatDiffList(recs []reportRecord, k reflect.Kind, ptrs *pointerReferences) textNode {
 	// Derive record name based on the data structure kind.
 	var name string
 	var formatKey func(reflect.Value) string
diff --git a/cmp/report_reflect.go b/cmp/report_reflect.go
index 28e0e92..45b4c97 100644
--- a/cmp/report_reflect.go
+++ b/cmp/report_reflect.go
@@ -15,7 +15,7 @@ import (
 	"github.com/google/go-cmp/cmp/internal/value"
 )
 
-type formatValueOptions struct {
+type FormatValueOptions struct {
 	// AvoidStringer controls whether to avoid calling custom stringer
 	// methods like error.Error or fmt.Stringer.String.
 	AvoidStringer bool
@@ -40,7 +40,7 @@ type formatValueOptions struct {
 
 // FormatType prints the type as if it were wrapping s.
 // This may return s as-is depending on the current type and TypeMode mode.
-func (opts formatOptions) FormatType(t reflect.Type, s textNode) textNode {
+func (opts FormatOptions) FormatType(t reflect.Type, s textNode) textNode {
 	// Check whether to emit the type or not.
 	switch opts.TypeMode {
 	case autoType:
@@ -103,7 +103,7 @@ func wrapParens(s textNode) textNode {
 
 // FormatValue prints the reflect.Value, taking extra care to avoid descending
 // into pointers already in ptrs. As pointers are visited, ptrs is also updated.
-func (opts formatOptions) FormatValue(v reflect.Value, parentKind reflect.Kind, ptrs *pointerReferences) (out textNode) {
+func (opts FormatOptions) FormatValue(v reflect.Value, parentKind reflect.Kind, ptrs *pointerReferences) (out textNode) {
 	if !v.IsValid() {
 		return nil
 	}
@@ -304,7 +304,7 @@ func (opts formatOptions) FormatValue(v reflect.Value, parentKind reflect.Kind,
 // formatMapKey formats v as if it were a map key.
 // The result is guaranteed to be a single line.
 func formatMapKey(v reflect.Value, disambiguate bool, ptrs *pointerReferences) string {
-	var opts formatOptions
+	var opts FormatOptions
 	opts.DiffMode = diffIdentical
 	opts.TypeMode = elideType
 	opts.PrintAddresses = disambiguate
diff --git a/cmp/report_slices.go b/cmp/report_slices.go
index 35315da..9a118dc 100644
--- a/cmp/report_slices.go
+++ b/cmp/report_slices.go
@@ -18,7 +18,7 @@ import (
 
 // CanFormatDiffSlice reports whether we support custom formatting for nodes
 // that are slices of primitive kinds or strings.
-func (opts formatOptions) CanFormatDiffSlice(v *valueNode) bool {
+func (opts FormatOptions) CanFormatDiffSlice(v *valueNode) bool {
 	switch {
 	case opts.DiffMode != diffUnknown:
 		return false // Must be formatting in diff mode
@@ -74,7 +74,7 @@ func (opts formatOptions) CanFormatDiffSlice(v *valueNode) bool {
 // FormatDiffSlice prints a diff for the slices (or strings) represented by v.
 // This provides custom-tailored logic to make printing of differences in
 // textual strings and slices of primitive kinds more readable.
-func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
+func (opts FormatOptions) FormatDiffSlice(v *valueNode) textNode {
 	assert(opts.DiffMode == diffUnknown)
 	t, vx, vy := v.Type, v.ValueX, v.ValueY
 
@@ -317,7 +317,7 @@ func formatASCII(s string) string {
 	return string(b)
 }
 
-func (opts formatOptions) formatDiffSlice(
+func (opts FormatOptions) formatDiffSlice(
 	vx, vy reflect.Value, chunkSize int, name string,
 	makeRec func(reflect.Value, diffMode) textRecord,
 ) (list textList) {