diff --git a/tests/test_validators.py b/tests/test_validators.py
new file mode 100644
index 0000000..2e0d8d8
--- /dev/null
+++ b/tests/test_validators.py
@@ -0,0 +1,96 @@
+"""Tests for syntax validation."""
+
+import pytest
+
+from config_convert.validators import validate
+
+
+class TestValidateJSON:
+    def test_valid_json(self):
+        is_valid, error = validate('{"name": "test"}', "json")
+        assert is_valid is True
+        assert error is None
+
+    def test_valid_json_pretty(self):
+        is_valid, error = validate('{\n  "name": "test\n"}', "json")
+        assert is_valid is True
+
+    def test_invalid_json(self):
+        is_valid, error = validate('{invalid}', "json")
+        assert is_valid is False
+        assert error is not None
+
+    def test_invalid_json_trailing_comma(self):
+        is_valid, error = validate('{"a": 1,}', "json")
+        assert is_valid is False
+
+
+class TestValidateYAML:
+    def test_valid_yaml(self):
+        is_valid, error = validate("name: test", "yaml")
+        assert is_valid is True
+        assert error is None
+
+    def test_valid_yaml_nested(self):
+        data = """database:
+   host: localhost
+   port: 5432
+ """
+        is_valid, error = validate(data, "yaml")
+        assert is_valid is True
+
+    def test_invalid_yaml(self):
+        is_valid, error = validate("[invalid: yaml", "yaml")
+        assert is_valid is False
+        assert error is not None
+
+
+class TestValidateTOML:
+    def test_valid_toml(self):
+        is_valid, error = validate('name = "test"', "toml")
+        assert is_valid is True
+        assert error is None
+
+    def test_valid_toml_nested(self):
+        data = """[database]
+ host = "localhost"
+ port = 5432
+ """
+        is_valid, error = validate(data, "toml")
+        assert is_valid is True
+
+    def test_invalid_toml(self):
+        is_valid, error = validate('invalid = "toml" extra', "toml")
+        assert is_valid is False
+
+
+class TestValidateENV:
+    def test_valid_env(self):
+        is_valid, error = validate("NAME=test\nVALUE=123", "env")
+        assert is_valid is True
+        assert error is None
+
+    def test_valid_env_with_comments(self):
+        data = "# comment\nNAME=test\n# another comment"
+        is_valid, error = validate(data, "env")
+        assert is_valid is True
+
+    def test_valid_env_with_empty_lines(self):
+        data = "NAME=test\n\nVALUE=123"
+        is_valid, error = validate(data, "env")
+        assert is_valid is True
+
+    def test_invalid_env_missing_equals(self):
+        is_valid, error = validate("NAME test", "env")
+        assert is_valid is False
+
+    def test_invalid_env_leading_space(self):
+        is_valid, error = validate(" NAME=test", "env")
+        assert is_valid is False
+
+
+class TestValidateUnsupported:
+    def test_unsupported_format(self):
+        is_valid, error = validate("test", "unsupported")
+        assert is_valid is False
+        assert "Unsupported format" in error.message