diff --git a/bundle/bundle.go b/bundle/bundle.go
index 4b08501dd7..652eaaa24c 100644
--- a/bundle/bundle.go
+++ b/bundle/bundle.go
@@ -23,6 +23,7 @@ import (
 	"github.com/open-policy-agent/opa/format"
 	"github.com/open-policy-agent/opa/internal/file/archive"
 	"github.com/open-policy-agent/opa/internal/merge"
+	"github.com/open-policy-agent/opa/loader/extension"
 	"github.com/open-policy-agent/opa/metrics"
 	"github.com/open-policy-agent/opa/util"
 )
@@ -600,10 +601,15 @@ func (r *Reader) Read() (Bundle, error) {
 				continue
 			}
 
+			var err error
 			var value interface{}
 
 			r.metrics.Timer(metrics.RegoDataParse).Start()
-			err := util.NewJSONDecoder(&buf).Decode(&value)
+			if handler := extension.FindExtension(".json"); handler != nil {
+				value, err = handler(buf.Bytes())
+			} else {
+				err = util.NewJSONDecoder(&buf).Decode(&value)
+			}
 			r.metrics.Timer(metrics.RegoDataParse).Stop()
 
 			if err != nil {
diff --git a/loader/extension/extension.go b/loader/extension/extension.go
new file mode 100644
index 0000000000..407ad96386
--- /dev/null
+++ b/loader/extension/extension.go
@@ -0,0 +1,46 @@
+// Copyright 2023 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package extension
+
+import (
+	"sync"
+)
+
+var pluginMtx sync.Mutex
+var bundleExtensions map[string]Handler
+
+// Handler is used to unmarshal a byte slice of a registered extension
+// EXPERIMENTAL: Please don't rely on this functionality, it may go
+// away or change in the future.
+type Handler func([]byte) (any, error)
+
+// RegisterExtension registers a Handler for a certain file extension, including
+// the dot: ".json", not "json".
+// EXPERIMENTAL: Please don't rely on this functionality, it may go
+// away or change in the future.
+func RegisterExtension(name string, handler Handler) {
+	pluginMtx.Lock()
+	defer pluginMtx.Unlock()
+
+	if bundleExtensions == nil {
+		bundleExtensions = map[string]Handler{}
+	}
+	bundleExtensions[name] = handler
+}
+
+// FindExtension ios used to look up a registered extension Handler
+// EXPERIMENTAL: Please don't rely on this functionality, it may go
+// away or change in the future.
+func FindExtension(ext string) Handler {
+	pluginMtx.Lock()
+	defer pluginMtx.Unlock()
+
+	for e, handler := range bundleExtensions {
+		if e == ext {
+			return handler
+		}
+	}
+	return nil
+}
diff --git a/loader/extension/extension_test.go b/loader/extension/extension_test.go
new file mode 100644
index 0000000000..2f92232405
--- /dev/null
+++ b/loader/extension/extension_test.go
@@ -0,0 +1,55 @@
+// Copyright 2023 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package extension_test
+
+import (
+	"crypto/rand"
+	"fmt"
+	"reflect"
+	"testing"
+	"testing/fstest"
+
+	"github.com/open-policy-agent/opa/loader"
+	"github.com/open-policy-agent/opa/loader/extension"
+	"github.com/open-policy-agent/opa/util"
+)
+
+func TestLoaderExtensionUnmarshal(t *testing.T) {
+	sentinelErr := fmt.Errorf("test handler called")
+	extension.RegisterExtension(".json", func([]byte) (any, error) {
+		return nil, sentinelErr
+	})
+	defer extension.RegisterExtension(".json", nil)
+
+	bs := make([]byte, 128)
+	_, err := rand.Read(bs)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var v any
+	if err := util.Unmarshal(bs, &v); err != sentinelErr {
+		t.Error(err)
+	}
+}
+
+func TestLoaderExtensionBundle(t *testing.T) {
+	data := map[string]any{"foo": "bar"}
+	extension.RegisterExtension(".json", func([]byte) (any, error) {
+		return data, nil
+	})
+	defer extension.RegisterExtension(".json", nil)
+
+	fs := fstest.MapFS{
+		"data.json": {},
+	}
+	ldr := loader.NewFileLoader().WithFS(fs)
+	res, err := ldr.All([]string{"."})
+	if err != nil {
+		t.Error(err)
+	}
+	if exp, act := data, res.Documents; !reflect.DeepEqual(exp, act) {
+		t.Errorf("expected %v, got %v", exp, act)
+	}
+}
diff --git a/loader/loader.go b/loader/loader.go
index d4d05943c2..c95a0df8a3 100644
--- a/loader/loader.go
+++ b/loader/loader.go
@@ -20,6 +20,7 @@ import (
 	"github.com/open-policy-agent/opa/bundle"
 	fileurl "github.com/open-policy-agent/opa/internal/file/url"
 	"github.com/open-policy-agent/opa/internal/merge"
+	"github.com/open-policy-agent/opa/loader/extension"
 	"github.com/open-policy-agent/opa/loader/filter"
 	"github.com/open-policy-agent/opa/metrics"
 	"github.com/open-policy-agent/opa/storage"
@@ -731,11 +732,16 @@ func loadRego(path string, bs []byte, m metrics.Metrics, opts ast.ParserOptions)
 
 func loadJSON(path string, bs []byte, m metrics.Metrics) (interface{}, error) {
 	m.Timer(metrics.RegoDataParse).Start()
-	buf := bytes.NewBuffer(bs)
-	decoder := util.NewJSONDecoder(buf)
+	var err error
 	var x interface{}
-	err := decoder.Decode(&x)
+	if handler := extension.FindExtension(".json"); handler != nil {
+		x, err = handler(bs)
+	} else {
+		buf := bytes.NewBuffer(bs)
+		err = util.NewJSONDecoder(buf).Decode(&x)
+	}
 	m.Timer(metrics.RegoDataParse).Stop()
+
 	if err != nil {
 		return nil, fmt.Errorf("%s: %w", path, err)
 	}
diff --git a/util/json.go b/util/json.go
index 283c496973..70ba660cf5 100644
--- a/util/json.go
+++ b/util/json.go
@@ -12,6 +12,8 @@ import (
 	"reflect"
 
 	"github.com/ghodss/yaml"
+
+	"github.com/open-policy-agent/opa/loader/extension"
 )
 
 // UnmarshalJSON parses the JSON encoded data and stores the result in the value
@@ -103,14 +105,25 @@ func Reference(x interface{}) *interface{} {
 	return &x
 }
 
-// Unmarshal decodes a YAML or JSON value into the specified type.
+// Unmarshal decodes a YAML, JSON or JSON extension value into the specified type.
 func Unmarshal(bs []byte, v interface{}) error {
 	if json.Valid(bs) {
 		return UnmarshalJSON(bs, v)
 	}
-	bs, err := yaml.YAMLToJSON(bs)
-	if err != nil {
-		return err
+	nbs, err := yaml.YAMLToJSON(bs)
+	if err == nil {
+		return UnmarshalJSON(nbs, v)
 	}
-	return UnmarshalJSON(bs, v)
+	// not json or yaml: try extensions
+	if value, ok := v.(*any); ok {
+		if handler := extension.FindExtension(".json"); handler != nil {
+			retval, err := handler(bs)
+			if err != nil {
+				return err
+			}
+			*value = retval
+			return nil
+		}
+	}
+	return err
 }