diff --git a/platform-independent/c/cli/src/mpw-cli.c b/platform-independent/c/cli/src/mpw-cli.c
index 00dbb635..486ca33d 100644
--- a/platform-independent/c/cli/src/mpw-cli.c
+++ b/platform-independent/c/cli/src/mpw-cli.c
@@ -156,7 +156,7 @@ typedef struct {
     const char *purposeResult;
     const char *resultState;
     const char *resultParam;
-    MPMarshalledUser *user;
+    MPMarshalledFile *file;
     MPMarshalledSite *site;
     MPMarshalledQuestion *question;
 } Operation;
@@ -185,7 +185,7 @@ void cli_save(Arguments *args, Operation *operation);
 
 MPMasterKeyProvider cli_masterKeyProvider_op(Operation *operation);
 MPMasterKeyProvider cli_masterKeyProvider_str(const char *masterPassword);
-void cli_masterKeyProvider_free();
+void cli_masterKeyProvider_free(void);
 
 /** ========================================================================
  *  MAIN                                                                     */
@@ -233,8 +233,8 @@ int main(const int argc, char *const argv[]) {
 
     // Operation summary.
     dbg( "-----------------" );
-    if (operation.user) {
-        dbg( "fullName         : %s", operation.user->fullName );
+    if (operation.file && operation.file->user) {
+        dbg( "fullName         : %s", operation.file->user->fullName );
         dbg( "identicon        : %s", operation.identicon );
         dbg( "sitesFormat      : %s%s", mpw_format_name( operation.sitesFormat ), operation.sitesFormatFixed? " (fixed)": "" );
         dbg( "sitesPath        : %s", operation.sitesPath );
@@ -272,7 +272,7 @@ void cli_free(Arguments *args, Operation *operation) {
         mpw_free_strings( &operation->fullName, &operation->masterPassword, &operation->siteName, NULL );
         mpw_free_strings( &operation->keyContext, &operation->resultState, &operation->resultParam, NULL );
         mpw_free_strings( &operation->identicon, &operation->sitesPath, NULL );
-        mpw_marshal_free( &operation->user );
+        mpw_marshal_free( &operation->file );
         operation->site = NULL;
         operation->question = NULL;
         cli_masterKeyProvider_free();
@@ -484,24 +484,25 @@ void cli_user(Arguments *args, Operation *operation) {
         }
     mpw_free( &extensions, count * sizeof( *extensions ) );
 
-    // Load the user object from mpsites.
-    if (!sitesFile)
+    if (!sitesFile) {
+        // If no user from mpsites, create a new one.
         mpw_free_string( &operation->sitesPath );
+        mpw_marshal_free( &operation->file );
+        operation->file = mpw_marshal_file( mpw_marshal_user(
+                operation->fullName, cli_masterKeyProvider_op( operation ), MPAlgorithmVersionCurrent ) );
+    }
 
     else {
-        // Read file.
+        // Load the user object from mpsites.
         const char *sitesInputData = mpw_read_file( sitesFile );
         if (!sitesInputData || ferror( sitesFile ))
             wrn( "Error while reading configuration file:\n  %s: %d", operation->sitesPath, ferror( sitesFile ) );
         fclose( sitesFile );
 
         // Parse file.
-        MPMarshalInfo *sitesInputInfo = mpw_marshal_read_info( sitesInputData );
-        MPMarshalFormat sitesInputFormat = args->sitesFormat? operation->sitesFormat: sitesInputInfo->format;
         MPMarshalError marshalError = { .type = MPMarshalSuccess };
-        mpw_marshal_info_free( &sitesInputInfo );
-        mpw_marshal_free( &operation->user );
-        operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat,
+        mpw_marshal_free( &operation->file );
+        operation->file = mpw_marshal_read( sitesInputData,
                 cli_masterKeyProvider_op( operation ), &marshalError );
         if (marshalError.type == MPMarshalErrorMasterPassword && operation->allowPasswordUpdate) {
             // Update master password in mpsites.
@@ -515,10 +516,11 @@ void cli_user(Arguments *args, Operation *operation) {
                     importMasterPassword = mpw_getpass( "Old master password: " );
                 }
 
-                mpw_marshal_free( &operation->user );
-                operation->user = mpw_marshal_read( sitesInputData, sitesInputFormat,
+                mpw_marshal_free( &operation->file );
+                operation->file = mpw_marshal_read( sitesInputData,
                         cli_masterKeyProvider_str( importMasterPassword ), &marshalError );
-                operation->user->masterKeyProvider = cli_masterKeyProvider_op( operation );
+                if (operation->file && operation->file->user)
+                    operation->file->user->masterKeyProvider = cli_masterKeyProvider_op( operation );
                 mpw_free_string( &importMasterPassword );
             }
         }
@@ -532,18 +534,12 @@ void cli_user(Arguments *args, Operation *operation) {
         }
 
         // Any other parse error.
-        if (!operation->user || marshalError.type != MPMarshalSuccess) {
+        if (!operation->file || !operation->file->user || marshalError.type != MPMarshalSuccess) {
             err( "Couldn't parse configuration file:\n  %s: %s", operation->sitesPath, marshalError.message );
             cli_free( args, operation );
             exit( EX_DATAERR );
         }
     }
-
-    // If no user from mpsites, create a new one.
-    if (!operation->user) {
-        operation->user = mpw_marshal_user(
-                operation->fullName, cli_masterKeyProvider_op( operation ), MPAlgorithmVersionCurrent );
-    }
 }
 
 void cli_site(Arguments *args, Operation *operation) {
@@ -552,14 +548,15 @@ void cli_site(Arguments *args, Operation *operation) {
         abort();
 
     // Load the site object from mpsites.
-    for (size_t s = 0; !operation->site && s < operation->user->sites_count; ++s)
-        if (strcmp( operation->siteName, (&operation->user->sites[s])->siteName ) == 0)
-            operation->site = &operation->user->sites[s];
+    MPMarshalledUser *user = operation->file->user;
+    for (size_t s = 0; !operation->site && s < user->sites_count; ++s)
+        if (strcmp( operation->siteName, (&user->sites[s])->siteName ) == 0)
+            operation->site = &user->sites[s];
 
     // If no site from mpsites, create a new one.
     if (!operation->site)
         operation->site = mpw_marshal_site(
-                operation->user, operation->siteName, operation->user->defaultType, MPCounterValueDefault, operation->user->algorithm );
+                user, operation->siteName, user->defaultType, MPCounterValueDefault, user->algorithm );
 }
 
 void cli_question(Arguments *args, Operation *operation) {
@@ -588,8 +585,8 @@ void cli_question(Arguments *args, Operation *operation) {
 void cli_operation(Arguments *args, Operation *operation) {
 
     mpw_free_string( &operation->identicon );
-    operation->user->identicon = mpw_identicon( operation->user->fullName, operation->masterPassword );
-    operation->identicon = mpw_identicon_render( operation->user->identicon );
+    operation->file->user->identicon = mpw_identicon( operation->file->user->fullName, operation->masterPassword );
+    operation->identicon = mpw_identicon_render( operation->file->user->identicon );
 
     if (!operation->site)
         abort();
@@ -703,9 +700,9 @@ void cli_algorithmVersion(Arguments *args, Operation *operation) {
 void cli_sitesRedacted(Arguments *args, Operation *operation) {
 
     if (args->sitesRedacted)
-        operation->user->redacted = strcmp( args->sitesRedacted, "1" ) == 0;
+        operation->file->user->redacted = strcmp( args->sitesRedacted, "1" ) == 0;
 
-    else if (!operation->user->redacted)
+    else if (!operation->file->user->redacted)
         wrn( "Sites configuration is not redacted.  Use -R 1 to change this." );
 }
 
@@ -716,21 +713,21 @@ void cli_mpw(Arguments *args, Operation *operation) {
 
     if (mpw_verbosity >= inf_level)
         fprintf( stderr, "%s's %s for %s:\n[ %s ]: ",
-                operation->user->fullName, operation->purposeResult, operation->site->siteName, operation->identicon );
+                operation->file->user->fullName, operation->purposeResult, operation->site->siteName, operation->identicon );
 
     // Determine master key.
     MPMasterKey masterKey = NULL;
-    if (operation->user->masterKeyProvider)
-        masterKey = operation->user->masterKeyProvider( operation->site->algorithm, operation->user->fullName );
+    if (operation->file->user->masterKeyProvider)
+        masterKey = operation->file->user->masterKeyProvider( operation->site->algorithm, operation->file->user->fullName );
     if (!masterKey) {
         ftl( "Couldn't derive master key." );
         cli_free( args, operation );
         exit( EX_SOFTWARE );
     }
     MPKeyID keyID = mpw_id_buf( masterKey, MPMasterKeySize );
-    if (!operation->user->keyID)
-        operation->user->keyID = mpw_strdup( keyID );
-    else if (!mpw_id_buf_equals( keyID, operation->user->keyID )) {
+    if (!operation->file->user->keyID)
+        operation->file->user->keyID = mpw_strdup( keyID );
+    else if (!mpw_id_buf_equals( keyID, operation->file->user->keyID )) {
         ftl( "Master key mismatch." );
         cli_free( args, operation );
         exit( EX_SOFTWARE );
@@ -792,7 +789,7 @@ void cli_mpw(Arguments *args, Operation *operation) {
     mpw_free_string( &result );
 
     // Update usage metadata.
-    operation->site->lastUsed = operation->user->lastUsed = time( NULL );
+    operation->site->lastUsed = operation->file->user->lastUsed = time( NULL );
     operation->site->uses++;
 }
 
@@ -807,7 +804,7 @@ void cli_save(Arguments *args, Operation *operation) {
         return;
 
     mpw_free_string( &operation->sitesPath );
-    operation->sitesPath = mpw_path( operation->user->fullName, extensions[0] );
+    operation->sitesPath = mpw_path( operation->file->user->fullName, extensions[0] );
     dbg( "Updating: %s (%s)", operation->sitesPath, mpw_format_name( operation->sitesFormat ) );
     mpw_free( &extensions, count * sizeof( *extensions ) );
 
@@ -818,7 +815,7 @@ void cli_save(Arguments *args, Operation *operation) {
     }
 
     MPMarshalError marshalError = { .type = MPMarshalSuccess };
-    const char *buf = mpw_marshal_write( operation->sitesFormat, operation->user, &marshalError );
+    const char *buf = mpw_marshal_write( operation->sitesFormat, operation->file, &marshalError );
     if (!buf || marshalError.type != MPMarshalSuccess)
         wrn( "Couldn't encode updated configuration file:\n  %s: %s", operation->sitesPath, marshalError.message );
 
diff --git a/platform-independent/c/core/src/mpw-marshal.c b/platform-independent/c/core/src/mpw-marshal.c
index c829ad3f..b95fc3ab 100644
--- a/platform-independent/c/core/src/mpw-marshal.c
+++ b/platform-independent/c/core/src/mpw-marshal.c
@@ -98,6 +98,21 @@ MPMarshalledQuestion *mpw_marshal_question(
     return question;
 }
 
+MPMarshalledFile *mpw_marshal_file(
+        MPMarshalledUser *user) {
+
+    MPMarshalledFile *file;
+    if (!user || !(file = malloc( sizeof( MPMarshalledFile ) )))
+        return NULL;
+
+    *file = (MPMarshalledFile){
+            .info = NULL,
+            .data = NULL,
+            .user = user,
+    };
+    return file;
+}
+
 bool mpw_marshal_info_free(
         MPMarshalInfo **info) {
 
@@ -111,15 +126,13 @@ bool mpw_marshal_info_free(
     return success;
 }
 
-bool mpw_marshal_free(
+static bool mpw_marshal_user_free(
         MPMarshalledUser **user) {
 
     if (!user || !*user)
         return true;
 
-    bool success = true;
-    success &= mpw_free_strings( &(*user)->fullName, NULL );
-    success &= mpw_free_strings( &(*user)->keyID, NULL );
+    bool success = mpw_free_strings( &(*user)->fullName, &(*user)->keyID, NULL );
 
     for (size_t s = 0; s < (*user)->sites_count; ++s) {
         MPMarshalledSite *site = &(*user)->sites[s];
@@ -138,10 +151,45 @@ bool mpw_marshal_free(
     return success;
 }
 
+static bool mpw_marshal_data_free(
+        MPMarshalledData **data) {
+
+    if (!data || !*data)
+        return true;
+
+    bool success = mpw_free_strings( &(*data)->key, &(*data)->str_value, NULL );
+    for (unsigned int c = 0; c < (*data)->obj_children_count; ++c)
+        success &= mpw_marshal_data_free( &(*data)->obj_children[c] );
+    success &= mpw_free( data, sizeof( MPMarshalledData ) );
+
+    return success;
+}
+
+bool mpw_marshal_free(
+        MPMarshalledFile **file) {
+
+    if (!file || !*file)
+        return true;
+
+    bool success = true;
+
+    success &= mpw_marshal_info_free( &(*file)->info );
+    success &= mpw_marshal_user_free( &(*file)->user );
+    success &= mpw_marshal_data_free( &(*file)->data );
+    success &= mpw_free( file, sizeof( MPMarshalledFile ) );
+
+    return success;
+}
+
 static const char *mpw_marshal_write_flat(
-        const MPMarshalledUser *user, MPMarshalError *error) {
+        const MPMarshalledFile *file, MPMarshalError *error) {
 
     *error = (MPMarshalError){ MPMarshalErrorInternal, "Unexpected internal error." };
+    MPMarshalledUser *user = file->user;
+    if (!user) {
+        *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing user." };
+        return NULL;
+    }
     if (!user->fullName || !strlen( user->fullName )) {
         *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing full name." };
         return NULL;
@@ -225,9 +273,14 @@ static const char *mpw_marshal_write_flat(
 #if MPW_JSON
 
 static const char *mpw_marshal_write_json(
-        const MPMarshalledUser *user, MPMarshalError *error) {
+        const MPMarshalledFile *file, MPMarshalError *error) {
 
     *error = (MPMarshalError){ MPMarshalErrorInternal, "Unexpected internal error." };
+    MPMarshalledUser *user = file->user;
+    if (!user) {
+        *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing user." };
+        return NULL;
+    }
     if (!user->fullName || !strlen( user->fullName )) {
         *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing full name." };
         return NULL;
@@ -361,17 +414,17 @@ static const char *mpw_marshal_write_json(
 #endif
 
 const char *mpw_marshal_write(
-        const MPMarshalFormat outFormat, const MPMarshalledUser *user, MPMarshalError *error) {
+        const MPMarshalFormat outFormat, const MPMarshalledFile *file, MPMarshalError *error) {
 
     switch (outFormat) {
         case MPMarshalFormatNone:
             *error = (MPMarshalError){ .type = MPMarshalSuccess };
             return NULL;
         case MPMarshalFormatFlat:
-            return mpw_marshal_write_flat( user, error );
+            return mpw_marshal_write_flat( file, error );
 #if MPW_JSON
         case MPMarshalFormatJSON:
-            return mpw_marshal_write_json( user, error );
+            return mpw_marshal_write_json( file, error );
 #endif
         default:
             *error = (MPMarshalError){ MPMarshalErrorFormat, mpw_str( "Unsupported output format: %u", outFormat ) };
@@ -430,7 +483,7 @@ static void mpw_marshal_read_flat_info(
     }
 }
 
-static MPMarshalledUser *mpw_marshal_read_flat(
+static MPMarshalledFile *mpw_marshal_read_flat(
         const char *in, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error) {
 
     *error = (MPMarshalError){ MPMarshalErrorInternal, "Unexpected internal error." };
@@ -474,23 +527,23 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                     *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
                 if (keyID && masterKey && !mpw_id_buf_equals( keyID, mpw_id_buf( masterKey, MPMasterKeySize ) )) {
                     *error = (MPMarshalError){ MPMarshalErrorMasterPassword, "Master key doesn't match key ID." };
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
 
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 if (!(user = mpw_marshal_user( fullName, masterKeyProvider, algorithm ))) {
                     *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't allocate a new user." };
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
 
@@ -512,7 +565,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &headerName, &headerValue, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
 
@@ -529,7 +582,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                     mpw_free_strings( &headerName, &headerValue, NULL );
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
                 algorithm = (MPAlgorithmVersion)value;
@@ -549,7 +602,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                     mpw_free_strings( &headerName, &headerValue, NULL );
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
                 defaultType = (MPResultType)value;
@@ -564,7 +617,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
             *error = (MPMarshalError){ MPMarshalErrorMissing, "Missing header: Full Name" };
             mpw_free_strings( &fullName, &keyID, NULL );
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             return NULL;
         }
         if (positionInLine >= endOfLine)
@@ -608,7 +661,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 *error = (MPMarshalError){ MPMarshalErrorFormat, mpw_str( "Unexpected import format: %u", format ) };
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
         }
@@ -621,7 +674,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
             long long int value = atoll( str_counter );
@@ -631,7 +684,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
             MPCounterValue siteCounter = (MPCounterValue)value;
@@ -642,7 +695,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
             MPAlgorithmVersion siteAlgorithm = (MPAlgorithmVersion)value;
@@ -653,7 +706,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
 
@@ -664,7 +717,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                 mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                 mpw_free_strings( &fullName, &keyID, NULL );
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 return NULL;
             }
 
@@ -679,7 +732,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
                     mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
                     mpw_free_strings( &fullName, &keyID, NULL );
                     mpw_free( &masterKey, MPMasterKeySize );
-                    mpw_marshal_free( &user );
+                    mpw_marshal_user_free( &user );
                     return NULL;
                 }
 
@@ -707,7 +760,7 @@ static MPMarshalledUser *mpw_marshal_read_flat(
             mpw_free_strings( &siteLoginState, &siteName, &siteResultState, NULL );
             mpw_free_strings( &fullName, &keyID, NULL );
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             return NULL;
         }
 
@@ -717,8 +770,15 @@ static MPMarshalledUser *mpw_marshal_read_flat(
     mpw_free_strings( &fullName, &keyID, NULL );
     mpw_free( &masterKey, MPMasterKeySize );
 
+    MPMarshalledFile *file = mpw_marshal_file( user );
+    if (!file) {
+        *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't allocate a new marshal file." };
+        mpw_marshal_user_free( &user );
+        return NULL;
+    }
+
     *error = (MPMarshalError){ .type = MPMarshalSuccess };
-    return user;
+    return file;
 }
 
 #if MPW_JSON
@@ -750,7 +810,7 @@ static void mpw_marshal_read_json_info(
     json_object_put( json_file );
 }
 
-static MPMarshalledUser *mpw_marshal_read_json(
+static MPMarshalledFile *mpw_marshal_read_json(
         const char *in, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error) {
 
     *error = (MPMarshalError){ MPMarshalErrorInternal, "Unexpected internal error." };
@@ -827,7 +887,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
     if (!(user = mpw_marshal_user( fullName, masterKeyProvider, algorithm ))) {
         *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't allocate a new user." };
         mpw_free( &masterKey, MPMasterKeySize );
-        mpw_marshal_free( &user );
+        mpw_marshal_user_free( &user );
         json_object_put( json_file );
         return NULL;
     }
@@ -848,7 +908,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (value < MPAlgorithmVersionFirst || value > MPAlgorithmVersionLast) {
             *error = (MPMarshalError){ MPMarshalErrorIllegal, mpw_str( "Invalid site algorithm version: %s: %d", siteName, value ) };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -857,7 +917,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (value < MPCounterValueFirst || value > MPCounterValueLast) {
             *error = (MPMarshalError){ MPMarshalErrorIllegal, mpw_str( "Invalid site counter: %s: %d", siteName, value ) };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -866,7 +926,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (!mpw_type_short_name( siteType )) {
             *error = (MPMarshalError){ MPMarshalErrorIllegal, mpw_str( "Invalid site type: %s: %u", siteName, siteType ) };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -875,7 +935,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (!mpw_type_short_name( siteLoginType )) {
             *error = (MPMarshalError){ MPMarshalErrorIllegal, mpw_str( "Invalid site login type: %s: %u", siteName, siteLoginType ) };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -886,7 +946,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (!siteLastUsed) {
             *error = (MPMarshalError){ MPMarshalErrorIllegal, mpw_str( "Invalid site last used: %s: %s", siteName, str_lastUsed ) };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -898,7 +958,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
         if (!site) {
             *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't allocate a new site." };
             mpw_free( &masterKey, MPMasterKeySize );
-            mpw_marshal_free( &user );
+            mpw_marshal_user_free( &user );
             json_object_put( json_file );
             return NULL;
         }
@@ -913,7 +973,7 @@ static MPMarshalledUser *mpw_marshal_read_json(
             if (!masterKeyProvider || !(masterKey = masterKeyProvider( site->algorithm, user->fullName ))) {
                 *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't derive master key." };
                 mpw_free( &masterKey, MPMasterKeySize );
-                mpw_marshal_free( &user );
+                mpw_marshal_user_free( &user );
                 json_object_put( json_file );
                 return NULL;
             }
@@ -958,8 +1018,15 @@ static MPMarshalledUser *mpw_marshal_read_json(
     mpw_free( &masterKey, MPMasterKeySize );
     json_object_put( json_file );
 
+    MPMarshalledFile *file = mpw_marshal_file( user );
+    if (!file) {
+        *error = (MPMarshalError){ MPMarshalErrorInternal, "Couldn't allocate a new marshal file." };
+        mpw_marshal_user_free( &user );
+        return NULL;
+    }
+
     *error = (MPMarshalError){ .type = MPMarshalSuccess };
-    return user;
+    return file;
 }
 
 #endif
@@ -993,23 +1060,31 @@ MPMarshalInfo *mpw_marshal_read_info(
     return info;
 }
 
-MPMarshalledUser *mpw_marshal_read(
-        const char *in, const MPMarshalFormat inFormat, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error) {
+MPMarshalledFile *mpw_marshal_read(
+        const char *in, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error) {
 
-    switch (inFormat) {
+    MPMarshalInfo *info = mpw_marshal_read_info( in );
+    MPMarshalledFile *file = NULL;
+    switch (info->format) {
         case MPMarshalFormatNone:
             *error = (MPMarshalError){ .type = MPMarshalSuccess };
-            return NULL;
+            break;
         case MPMarshalFormatFlat:
-            return mpw_marshal_read_flat( in, masterKeyProvider, error );
+            file = mpw_marshal_read_flat( in, masterKeyProvider, error );
+            break;
 #if MPW_JSON
         case MPMarshalFormatJSON:
-            return mpw_marshal_read_json( in, masterKeyProvider, error );
+            file = mpw_marshal_read_json( in, masterKeyProvider, error );
+            break;
 #endif
         default:
-            *error = (MPMarshalError){ MPMarshalErrorFormat, mpw_str( "Unsupported input format: %u", inFormat ) };
-            return NULL;
+            *error = (MPMarshalError){ MPMarshalErrorFormat, mpw_str( "Unsupported input format: %u", info->format ) };
+            break;
     }
+    if (file)
+        file->info = info;
+
+    return file;
 }
 
 const MPMarshalFormat mpw_format_named(
diff --git a/platform-independent/c/core/src/mpw-marshal.h b/platform-independent/c/core/src/mpw-marshal.h
index 5fee9970..27d57438 100644
--- a/platform-independent/c/core/src/mpw-marshal.h
+++ b/platform-independent/c/core/src/mpw-marshal.h
@@ -68,6 +68,19 @@ typedef struct MPMarshalError {
     const char *message;
 } MPMarshalError;
 
+typedef struct MPMarshalInfo {
+    MPMarshalFormat format;
+    time_t exportDate;
+    bool redacted;
+
+    MPAlgorithmVersion algorithm;
+    unsigned int avatar;
+    const char *fullName;
+    MPIdenticon identicon;
+    const char *keyID;
+    time_t lastUsed;
+} MPMarshalInfo;
+
 typedef struct MPMarshalledQuestion {
     const char *keyword;
     MPResultType type;
@@ -109,33 +122,44 @@ typedef struct MPMarshalledUser {
     MPMarshalledSite *sites;
 } MPMarshalledUser;
 
-typedef struct MPMarshalInfo {
-    MPMarshalFormat format;
-    time_t exportDate;
-    bool redacted;
+typedef struct MPMarshalledData {
+    // If data is held in a parent object.
+    const char *key;
+    // If data is held in a parent array.
+    unsigned int index;
 
-    MPAlgorithmVersion algorithm;
-    unsigned int avatar;
-    const char *fullName;
-    MPIdenticon identicon;
-    const char *keyID;
-    time_t lastUsed;
-} MPMarshalInfo;
+    // If data is a string.
+    const char *str_value;
+    // If data is a boolean.
+    bool bool_value;
+    // If data is a number.
+    double num_value;
+
+    // If data is an object or array.
+    struct MPMarshalledData **obj_children;
+    size_t obj_children_count;
+} MPMarshalledData;
+
+typedef struct MPMarshalledFile {
+    MPMarshalInfo *info;
+    MPMarshalledUser *user;
+    MPMarshalledData *data;
+} MPMarshalledFile;
 
 //// Marshalling.
 
 /** Write the user and all associated data out using the given marshalling format.
  * @return A string (allocated), or NULL if the format is unrecognized, does not support marshalling or a format error occurred. */
 const char *mpw_marshal_write(
-        const MPMarshalFormat outFormat, const MPMarshalledUser *user, MPMarshalError *error);
+        const MPMarshalFormat outFormat, const MPMarshalledFile *file, MPMarshalError *error);
 /** Best effort parse of metadata on the sites in the input buffer.  Fields that could not be parsed remain at their type's initial value.
  * @return A metadata object (allocated); NULL if the object could not be allocated or the format was not understood. */
 MPMarshalInfo *mpw_marshal_read_info(
         const char *in);
 /** Unmarshall sites in the given input buffer by parsing it using the given marshalling format.
  * @return A user object (allocated), or NULL if the format provides no marshalling or a format error occurred. */
-MPMarshalledUser *mpw_marshal_read(
-        const char *in, const MPMarshalFormat inFormat, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error);
+MPMarshalledFile *mpw_marshal_read(
+        const char *in, MPMasterKeyProvider masterKeyProvider, MPMarshalError *error);
 
 //// Utilities.
 
@@ -152,12 +176,16 @@ MPMarshalledSite *mpw_marshal_site(
  * @return A question object (allocated), or NULL if the marshalled question couldn't be allocated. */
 MPMarshalledQuestion *mpw_marshal_question(
         MPMarshalledSite *site, const char *keyword);
+/** Create a new file to marshal a user into.
+ * @return A file object (allocated), or NULL if the user is missing or the marshalled file couldn't be allocated. */
+MPMarshalledFile *mpw_marshal_file(
+        MPMarshalledUser *user);
 
 /** Free the given user object and all associated data. */
 bool mpw_marshal_info_free(
         MPMarshalInfo **info);
 bool mpw_marshal_free(
-        MPMarshalledUser **user);
+        MPMarshalledFile **user);
 
 //// Format.
 
diff --git a/platform-independent/c/core/src/mpw-types.h b/platform-independent/c/core/src/mpw-types.h
index f4e25020..b69588f7 100644
--- a/platform-independent/c/core/src/mpw-types.h
+++ b/platform-independent/c/core/src/mpw-types.h
@@ -36,6 +36,12 @@ MP_LIBS_END
 #define mpw_enum(_type, _name) _type _name; enum
 #endif
 
+#ifdef NS_OPTIONS
+#define mpw_opts(_type, _name) NS_OPTIONS(_type, _name)
+#else
+#define mpw_opts(_type, _name) _type _name; enum
+#endif
+
 //// Types.
 
 extern const size_t MPMasterKeySize, MPSiteKeySize; /* bytes */
@@ -52,7 +58,7 @@ typedef mpw_enum( uint8_t, MPKeyPurpose ) {
 };
 
 // bit 4 - 9
-typedef mpw_enum( uint16_t, MPResultTypeClass ) {
+typedef mpw_opts( uint16_t, MPResultTypeClass ) {
     /** Use the site key to generate a password from a template. */
             MPResultTypeClassTemplate = 1 << 4,
     /** Use the site key to encrypt and decrypt a stateful entity. */
@@ -62,7 +68,7 @@ typedef mpw_enum( uint16_t, MPResultTypeClass ) {
 };
 
 // bit 10 - 15
-typedef mpw_enum( uint16_t, MPSiteFeature ) {
+typedef mpw_opts( uint16_t, MPSiteFeature ) {
     /** Export the key-protected content data. */
             MPSiteFeatureExportContent = 1 << 10,
     /** Never export content. */