diff --git a/autostate/types.go b/autostate/types.go
new file mode 100644
index 00000000..cd74a72f
--- /dev/null
+++ b/autostate/types.go
@@ -0,0 +1,71 @@
+package autostate
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+const (
+	// Version is the max version of the config file format supported
+	Version = 1
+)
+
+var (
+	// ErrInvalidVersion is returned when the config file version is not supported.
+	ErrInvalidVersion = errors.New("invalid version")
+
+	// ErrUnsupportedStorageType is returned when the storage type is not supported.
+	ErrUnsupportedStorageType = errors.New("unsupported storage type")
+)
+
+// Duration is a wrapper around time.Duration that allows us to unmarshal
+type Duration time.Duration
+
+// MarshalJSON marshals the duration as a string
+func (d Duration) MarshalJSON() ([]byte, error) {
+	return json.Marshal(time.Duration(d).String())
+}
+
+// UnmarshalJSON unmarshals the duration from a string or a float64
+func (d *Duration) UnmarshalJSON(b []byte) error {
+	var v interface{}
+	if err := json.Unmarshal(b, &v); err != nil {
+		return err
+	}
+	switch value := v.(type) {
+	case float64:
+		*d = Duration(time.Duration(value))
+		return nil
+	case string:
+		tmp, err := time.ParseDuration(value)
+		if err != nil {
+			return err
+		}
+		*d = Duration(tmp)
+		return nil
+	default:
+		return errors.New("invalid duration")
+	}
+}
+
+// StorageType is a wrapper around string that allows us to unmarshal
+type StorageType string
+
+// UnmarshalJSON unmarshals the storage type from a string and validates it
+func (s *StorageType) UnmarshalJSON(b []byte) error {
+	var v interface{}
+	if err := json.Unmarshal(b, &v); err != nil {
+		return err
+	}
+	switch value := v.(type) {
+	case string:
+		*s = StorageType(value)
+		if *s != "s3" {
+			return ErrUnsupportedStorageType
+		}
+		return nil
+	default:
+		return ErrUnsupportedStorageType
+	}
+}