diff --git a/vlib/json/json_test.v b/vlib/json/json_test.v
index fe02738746..c7db774a1e 100644
--- a/vlib/json/json_test.v
+++ b/vlib/json/json_test.v
@@ -7,10 +7,10 @@ enum JobTitle {
 }
 
 struct Employee {
-	name string
-	age  int
+	name   string
+	age    int
 	salary f32
-	title JobTitle
+	title  JobTitle
 }
 
 fn test_simple() {
@@ -37,10 +37,10 @@ struct User2 {
 struct User {
 	age           int
 	nums          []int
-	last_name     string [json:lastName]
-	is_registered bool   [json:IsRegistered]
-	typ           int    [json:'type']
-	pets          string [raw; json:'pet_animals']
+	last_name     string [json: lastName]
+	is_registered bool   [json: IsRegistered]
+	typ           int    [json: 'type']
+	pets          string [raw; json: 'pet_animals']
 }
 
 fn test_parse_user() {
@@ -113,3 +113,149 @@ fn test_struct_in_struct() {
 	assert country.cities[1].name == 'Manchester'
 	println(country.cities)
 }
+
+fn test_encode_map() {
+	expected := '{"one":1,"two":2,"three":3,"four":4}'
+	numbers := {
+		'one': 1
+		'two': 2
+		'three': 3
+		'four': 4
+	}
+	out := json.encode(numbers)
+	println(out)
+	assert out == expected
+}
+
+fn test_parse_map() {
+	expected := {
+		'one': 1
+		'two': 2
+		'three': 3
+		'four': 4
+	}
+	out := json.decode(map[string]int, '{"one":1,"two":2,"three":3,"four":4}') or {
+		assert false
+		r := {
+			'': 0
+		}
+		r
+	}
+	println(out)
+	assert out == expected
+}
+
+struct Data {
+	countries []Country
+	users     map[string]User
+	extra     map[string]map[string]int
+}
+
+fn test_nested_type() {
+	data_expected := '{"countries":[{"cities":[{"name":"London"},{"name":"Manchester"}],"name":"UK"},{"cities":[{"name":"Donlon"},{"name":"Termanches"}],"name":"KU"}],"users":{"Foo":{"age":10,"nums":[1,2,3],"lastName":"Johnson","IsRegistered":true,"type":0,"pet_animals":"little foo"},"Boo":{"age":20,"nums":[5,3,1],"lastName":"Smith","IsRegistered":false,"type":4,"pet_animals":"little boo"}},"extra":{"2":{"n1":2,"n2":4,"n3":8,"n4":16},"3":{"n1":3,"n2":9,"n3":27,"n4":81}}}'
+
+	data := Data{
+		countries: [
+			Country{
+				name: 'UK'
+				cities: [City{'London'},
+					City{'Manchester'},
+				]
+			},
+			Country{
+				name: 'KU'
+				cities: [City{'Donlon'},
+					City{'Termanches'},
+				]
+			},
+		]
+		users: {
+			'Foo': User{
+				age: 10
+				nums: [1, 2, 3]
+				last_name: 'Johnson'
+				is_registered: true
+				typ: 0
+				pets: 'little foo'
+			},
+			'Boo': User{
+				age: 20
+				nums: [5, 3, 1]
+				last_name: 'Smith'
+				is_registered: false
+				typ: 4
+				pets: 'little boo'
+			}
+		},
+		extra: {
+			'2': {
+				'n1': 2
+				'n2': 4
+				'n3': 8
+				'n4': 16
+			},
+			'3': {
+				'n1': 3
+				'n2': 9
+				'n3': 27
+				'n4': 81
+			},
+		}
+	}
+	out := json.encode(data)
+	println(out)
+	assert out == data_expected
+
+	data2 := json.decode(Data, data_expected) or {
+		assert false
+		Data{}
+	}
+	assert data2.countries.len == data.countries.len
+	for i in 0..1 {
+		assert data2.countries[i].name == data.countries[i].name
+		assert data2.countries[i].cities.len == data.countries[i].cities.len
+		for j in 0..1 {
+			assert data2.countries[i].cities[j].name == data.countries[i].cities[j].name
+		}
+	}
+	
+	for key, user in data.users {
+		assert data2.users[key].age == user.age
+		assert data2.users[key].nums == user.nums
+		assert data2.users[key].last_name == user.last_name
+		assert data2.users[key].is_registered == user.is_registered
+		assert data2.users[key].typ == user.typ
+		// assert data2.users[key].pets == user.pets // TODO FIX
+	}
+
+	for k, v in data.extra {
+		for k2, v2 in v {
+			assert data2.extra[k][k2] == v2
+		}
+	}
+}
+
+fn test_errors() {
+	invalid_array := fn () {
+		data := '{"countries":[{"cities":[{"name":"London"},{"name":"Manchester"}],"name":"UK"},{"cities":{"name":"Donlon"},"name":"KU"}],"users":{"Foo":{"age":10,"nums":[1,2,3],"lastName":"Johnson","IsRegistered":true,"type":0,"pet_animals":"little foo"},"Boo":{"age":20,"nums":[5,3,1],"lastName":"Smith","IsRegistered":false,"type":4,"pet_animals":"little boo"}},"extra":{"2":{"n1":2,"n2":4,"n3":8,"n4":16},"3":{"n1":3,"n2":9,"n3":27,"n4":81}}}'
+
+		json.decode(Data, data) or {
+			println(err)
+			assert err.starts_with('Json element is not an array:')
+			return
+		}
+		assert false
+	}
+	invalid_object := fn() {
+		data := '{"countries":[{"cities":[{"name":"London"},{"name":"Manchester"}],"name":"UK"},{"cities":[{"name":"Donlon"},{"name":"Termanches"}],"name":"KU"}],"users":[{"age":10,"nums":[1,2,3],"lastName":"Johnson","IsRegistered":true,"type":0,"pet_animals":"little foo"},{"age":20,"nums":[5,3,1],"lastName":"Smith","IsRegistered":false,"type":4,"pet_animals":"little boo"}],"extra":{"2":{"n1":2,"n2":4,"n3":8,"n4":16},"3":{"n1":3,"n2":9,"n3":27,"n4":81}}}'
+
+		json.decode(Data, data) or {
+			println(err)
+			assert err.starts_with('Json element is not an object:')
+			return
+		}
+		assert false
+	}
+	invalid_array()
+	invalid_object()
+}
diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index dceeaa58bf..d6542b8dc5 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -454,19 +454,42 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 	is_json_decode := name == 'json.decode'
 	g.is_json_fn = is_json_encode || is_json_decode
 	mut json_type_str := ''
+	mut json_obj := ''
 	if g.is_json_fn {
-		if name == 'json.encode' {
-			g.write('json__json_print(')
+		json_obj = g.new_tmp_var()
+		mut tmp2 := ''
+		cur_line := g.go_before_stmt(0)
+		if is_json_encode {
 			g.gen_json_for_type(node.args[0].typ)
 			json_type_str = g.table.get_type_symbol(node.args[0].typ).name
+
+			// `json__encode` => `json__encode_User`
+			encode_name := c_name(name) + '_' + util.no_dots(json_type_str)
+			g.writeln('// json.encode')
+			g.write('cJSON* $json_obj = ${encode_name}(')
+			g.call_args(node.args, node.expected_arg_types)
+			g.writeln(');')
+			tmp2 = g.new_tmp_var()
+			g.writeln('string $tmp2 = json__json_print($json_obj);')
 		} else {
-			g.insert_before_stmt('// json.decode')
 			ast_type := node.args[0].expr as ast.Type
 			// `json.decode(User, s)` => json.decode_User(s)
-			sym := g.table.get_type_symbol(ast_type.typ)
-			name += '_' + sym.name
+			typ := c_name(g.table.get_type_symbol(ast_type.typ).name)
+			fn_name := c_name(name) + '_' + typ
 			g.gen_json_for_type(ast_type.typ)
+			g.writeln('// json.decode')
+			g.write('cJSON* $json_obj = json__json_parse(')
+			// Skip the first argument in json.decode which is a type
+			// its name was already used to generate the function call
+			g.call_args(node.args[1..], node.expected_arg_types)
+			g.writeln(');')
+			tmp2 = g.new_tmp_var()
+			g.writeln('Option_$typ $tmp2 = $fn_name ($json_obj);')
 		}
+		g.write('cJSON_Delete($json_obj);')
+		g.write('\n$cur_line')
+		name = ''
+		json_obj = tmp2
 	}
 	if node.language == .c {
 		// Skip "C."
@@ -475,10 +498,6 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 	} else {
 		name = c_name(name)
 	}
-	if is_json_encode {
-		// `json__encode` => `json__encode_User`
-		name += '_' + util.no_dots(json_type_str)
-	}
 	if node.generic_type != table.void_type && node.generic_type != 0 {
 		// `foo<int>()` => `foo_int()`
 		name += '_' + g.typ(node.generic_type)
@@ -581,21 +600,15 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		g.write(')')
 	} else {
 		g.write('${g.get_ternary_name(name)}(')
-		if is_json_decode {
-			g.write('json__json_parse(')
-			// Skip the first argument in json.decode which is a type
-			// its name was already used to generate the function call
-			g.call_args(node.args[1..], node.expected_arg_types)
+		if g.is_json_fn {
+			g.write(json_obj)
 		} else {
 			g.call_args(node.args, node.expected_arg_types)
 		}
 		g.write(')')
 	}
 	g.is_c_call = false
-	if g.is_json_fn {
-		g.write(')')
-		g.is_json_fn = false
-	}
+	g.is_json_fn = false
 	if free_tmp_arg_vars {
 		g.tmp_idxs.clear()
 	}
diff --git a/vlib/v/gen/json.v b/vlib/v/gen/json.v
index ff2386f5d3..3322860ae5 100644
--- a/vlib/v/gen/json.v
+++ b/vlib/v/gen/json.v
@@ -63,15 +63,24 @@ $dec_fn_dec {
 	g.json_forward_decls.writeln('$enc_fn_dec;\n')
 	enc.writeln('
 $enc_fn_dec {
-\tcJSON *o = cJSON_CreateObject();')
+\tcJSON *o;')
 	if sym.kind == .array {
 		// Handle arrays
 		value_type := g.table.value_type(typ)
+		// If we have `[]Profile`, have to register a Profile en(de)coder first
 		g.gen_json_for_type(value_type)
 		dec.writeln(g.decode_array(value_type))
 		enc.writeln(g.encode_array(value_type))
 		// enc += g.encode_array(t)
+	} else if sym.kind == .map {
+		// Handle maps
+		m := sym.info as table.Map		
+		g.gen_json_for_type(m.key_type)
+		g.gen_json_for_type(m.value_type)
+		dec.writeln(g.decode_map(m.key_type, m.value_type))
+		enc.writeln(g.encode_map(m.key_type, m.value_type))
 	} else {
+		enc.writeln('\to = cJSON_CreateObject();')
 		// Structs. Range through fields
 		if sym.info !is table.Struct {
 			verror('json: $sym.name is not struct')
@@ -90,19 +99,24 @@ $enc_fn_dec {
 			}
 			field_type := g.typ(field.typ)
 			if field.attrs.contains('raw') {
-				dec.writeln(' res . ${c_name(field.name)} = tos2(cJSON_PrintUnformatted(' + 'js_get(root, "$name")));')
+				dec.writeln('\tres.${c_name(field.name)} = tos2(cJSON_PrintUnformatted(' + 'js_get(root, "$name")));')
 			} else {
 				// Now generate decoders for all field types in this struct
 				// need to do it here so that these functions are generated first
 				g.gen_json_for_type(field.typ)
 				dec_name := js_dec_name(field_type)
 				if is_js_prim(field_type) {
-					dec.writeln(' res . ${c_name(field.name)} = $dec_name (js_get(root, "$name"));')
+					dec.writeln('\tres.${c_name(field.name)} = $dec_name (js_get(root, "$name"));')
 				} else if g.table.get_type_symbol(field.typ).kind == .enum_ {
-					dec.writeln(' res . ${c_name(field.name)} = json__decode_u64(js_get(root, "$name"));')
+					dec.writeln('\tres.${c_name(field.name)} = json__decode_u64(js_get(root, "$name"));')
 				} else {
 					// dec.writeln(' $dec_name (js_get(root, "$name"), & (res . $field.name));')
-					dec.writeln('  res . ${c_name(field.name)} = *($field_type*) $dec_name (js_get(root,"$name")).data;')
+					tmp := g.new_tmp_var()
+					dec.writeln('\tOption_$field_type $tmp = $dec_name (js_get(root,"$name"));')
+					dec.writeln('\tif(!${tmp}.ok) {')
+					dec.writeln('\t\treturn *(Option_$styp*) &$tmp;')
+					dec.writeln('\t}')
+					dec.writeln('\tres.${c_name(field.name)} = *($field_type*) ${tmp}.data;')
 				}
 			}
 			mut enc_name := js_enc_name(field_type)
@@ -115,9 +129,9 @@ $enc_fn_dec {
 	}
 	// cJSON_delete
 	// p.cgen.fns << '$dec return opt_ok(res); \n}'
-	dec.writeln('Option_$styp ret;')
-	dec.writeln('opt_ok2(&res, (OptionBase*)&ret, sizeof(res));')
-	dec.writeln('return ret;\n}')
+	dec.writeln('\tOption_$styp ret;')
+	dec.writeln('\topt_ok2(&res, (OptionBase*)&ret, sizeof(res));')
+	dec.writeln('\treturn ret;\n}')
 	enc.writeln('\treturn o;\n}')
 	g.definitions.writeln(dec.str())
 	g.gowrappers.writeln(enc.str())
@@ -142,22 +156,32 @@ fn is_js_prim(typ string) bool {
 fn (mut g Gen) decode_array(value_type table.Type) string {
 	styp := g.typ(value_type)
 	fn_name := js_dec_name(styp)
-	// If we have `[]Profile`, have to register a Profile en(de)coder first
-	g.gen_json_for_type(value_type)
+	
 	mut s := ''
 	if is_js_prim(styp) {
 		s = '$styp val = ${fn_name}(jsval); '
 	} else {
-		s = '\t$styp val = *($styp*) ${fn_name}(jsval).data; '
+		s = '
+		Option_$styp val2 = $fn_name (jsval);
+		if(!val2.ok) {
+			array_free(&res);
+			return *(Option_array_${styp}*)&val2;
+		}
+		$styp val = *($styp*)val2.data;
+'
 	}
 	return '
-res = __new_array(0, 0, sizeof($styp));
-const cJSON *jsval = NULL;
-cJSON_ArrayForEach(jsval, root)
-{
-$s
-	array_push(&res, &val);
-}
+	if(!cJSON_IsArray(root)) {
+		Option err = v_error( string_add(tos_lit("Json element is not an array: "), tos2(cJSON_PrintUnformatted(root))) );
+		return *(Option_array_${styp} *)&err;
+	}
+	res = __new_array(0, 0, sizeof($styp));
+	const cJSON *jsval = NULL;
+	cJSON_ArrayForEach(jsval, root)
+	{
+	$s
+		array_push(&res, &val);
+	}
 '
 }
 
@@ -165,9 +189,75 @@ fn (mut g Gen) encode_array(value_type table.Type) string {
 	styp := g.typ(value_type)
 	fn_name := js_enc_name(styp)
 	return '
-o = cJSON_CreateArray();
-for (int i = 0; i < val.len; i++){
-	cJSON_AddItemToArray(o, $fn_name (  (($styp*)val.data)[i]  ));
-}
+	o = cJSON_CreateArray();
+	for (int i = 0; i < val.len; i++){
+		cJSON_AddItemToArray(o, $fn_name (  (($styp*)val.data)[i]  ));
+	}
+'
+}
+
+fn (mut g Gen) decode_map(key_type, value_type table.Type) string {
+	
+	styp := g.typ(key_type)
+
+	styp_v := g.typ(value_type)
+	fn_name_v := js_dec_name(styp_v)
+
+	mut s := ''
+	if is_js_prim(styp_v) {
+		s = '$styp_v val = $fn_name_v (js_get(root, jsval->string));'
+	} else {
+		s = '
+		Option_$styp_v val2 = $fn_name_v (js_get(root, jsval->string));
+		if(!val2.ok) {
+			map_free(&res);
+			return *(Option_map_${styp}_${styp_v}*)&val2;
+		}
+		$styp_v val = *($styp_v*)val2.data;
+'
+	}
+
+	return '
+	if(!cJSON_IsObject(root)) {
+		Option err = v_error( string_add(tos_lit("Json element is not an object: "), tos2(cJSON_PrintUnformatted(root))) );
+		return *(Option_map_${styp}_${styp_v} *)&err;
+	}
+	res = new_map_1(sizeof($styp_v));
+	cJSON *jsval = NULL;
+	cJSON_ArrayForEach(jsval, root)
+	{
+		$s
+		map_set(&res, tos2( (byteptr) jsval->string ) , &val );
+	}
+'
+}
+
+fn (mut g Gen) encode_map(key_type, value_type table.Type) string {
+	styp := g.typ(key_type)
+
+	styp_v := g.typ(value_type)
+	fn_name_v := js_enc_name(styp_v)
+
+	zero := g.type_default(value_type)
+
+	keys_tmp := g.new_tmp_var()
+
+	mut key := 'string key = '
+	if key_type.is_string() {
+		key += '(($styp*)${keys_tmp}.data)[i];'
+	} else {
+		// g.gen_str_for_type(key_type)
+		// key += '${styp}_str((($styp*)${keys_tmp}.data)[i]);'
+		verror('json: encode only maps with string keys')
+	}
+
+	return '
+	o = cJSON_CreateObject();
+	array_$styp $keys_tmp = map_keys(&val);
+	for (int i = 0; i < ${keys_tmp}.len; ++i) {
+		$key
+		cJSON_AddItemToObject(o, (char*) key.str, $fn_name_v ( *($styp_v*) map_get(val, key, &($styp_v[]) { $zero } ) ) );
+	}
+	array_free(&$keys_tmp);
 '
 }