diff --git a/README.md b/README.md
index 9d3bd37..e043abe 100644
--- a/README.md
+++ b/README.md
@@ -200,6 +200,12 @@ render("{{ float(\"1.8\") > 2 }}", data); // false
 // Set default values if variables are not defined
 render("Hello {{ default(neighbour, \"my friend\") }}!", data); // "Hello Peter!"
 render("Hello {{ default(colleague, \"my friend\") }}!", data); // "Hello my friend!"
+
+// Check if a key exists in an object
+render("{{ exists(\"guests\") }}", data); // "true"
+render("{{ exists(\"city\") }}", data); // "false"
+render("{{ existsIn(time, \"start\") }}", data); // "true"
+render("{{ existsIn(time, neighbour) }}", data); // "false"
 ```
 
 ### Callbacks
diff --git a/src/inja.hpp b/src/inja.hpp
index 1647eae..b1d4c65 100644
--- a/src/inja.hpp
+++ b/src/inja.hpp
@@ -279,6 +279,8 @@ struct Parsed {
 		Sort,
 		Upper,
 		ReadJson,
+		Exists,
+		ExistsInObject,
 		Default
 	};
 
@@ -513,6 +515,15 @@ public:
 				Parsed::CallbackSignature signature = std::make_pair(element.command, element.args.size());
 				return map_callbacks.at(signature)(element.args, data);
 			}
+			case Parsed::Function::Exists: {
+				const std::string name = eval_expression<std::string>(element.args[0], data);
+				return data.find(name) != data.end();
+			}
+			case Parsed::Function::ExistsInObject: {
+				const std::string name = eval_expression<std::string>(element.args[1], data);
+				const json d = eval_expression(element.args[0], data);
+				return d.find(name) != d.end();
+			}
 		}
 
 		inja_throw("render_error", "unknown function in renderer: " + element.command);
@@ -688,6 +699,8 @@ public:
 		{Parsed::Function::Round, function_regex("round", 2)},
 		{Parsed::Function::Sort, function_regex("sort", 1)},
 		{Parsed::Function::Upper, function_regex("upper", 1)},
+		{Parsed::Function::Exists, function_regex("exists", 1)},
+		{Parsed::Function::ExistsInObject, function_regex("existsIn", 2)},
 		{Parsed::Function::ReadJson, Regex{"\\s*([^\\(\\)]*\\S)\\s*"}}
 	};
 
diff --git a/test/src/unit-renderer.cpp b/test/src/unit-renderer.cpp
index 41098c4..4acad8c 100644
--- a/test/src/unit-renderer.cpp
+++ b/test/src/unit-renderer.cpp
@@ -104,6 +104,9 @@ TEST_CASE("functions") {
 	data["city"] = "New York";
 	data["names"] = {"Jeff", "Seb", "Peter", "Tom"};
 	data["temperature"] = 25.6789;
+	data["brother"]["name"] = "Chris";
+	data["brother"]["daughters"] = {"Maria", "Helen"};
+	data["property"] = "name";
 
 	SECTION("upper") {
 		CHECK( env.render("{{ upper(name) }}", data) == "PETER" );
@@ -203,6 +206,22 @@ TEST_CASE("functions") {
 		CHECK( env.render("{{ default(surname, \"nobody\") }}", data) == "nobody" );
 		CHECK_THROWS_WITH( env.render("{{ default(surname, lastname) }}", data), "[inja.exception.render_error] variable '/lastname' not found" );
 	}
+
+	SECTION("exists") {
+		CHECK( env.render("{{ exists(\"name\") }}", data) == "true" );
+		CHECK( env.render("{{ exists(\"zipcode\") }}", data) == "false" );
+		CHECK( env.render("{{ exists(name) }}", data) == "false" );
+		CHECK( env.render("{{ exists(property) }}", data) == "true" );
+	}
+
+	SECTION("existsIn") {
+		CHECK( env.render("{{ existsIn(brother, \"name\") }}", data) == "true" );
+		CHECK( env.render("{{ existsIn(brother, \"parents\") }}", data) == "false" );
+		CHECK( env.render("{{ existsIn(brother, property) }}", data) == "true" );
+		CHECK( env.render("{{ existsIn(brother, name) }}", data) == "false" );
+		CHECK_THROWS_WITH( env.render("{{ existsIn(sister, \"lastname\") }}", data), "[inja.exception.render_error] variable '/sister' not found" );
+		CHECK_THROWS_WITH( env.render("{{ existsIn(brother, sister) }}", data), "[inja.exception.render_error] variable '/sister' not found" );
+	}
 }
 
 TEST_CASE("callbacks") {
diff --git a/test/src/unit-string-helper.cpp b/test/src/unit-string-helper.cpp
index f6ee964..87f4618 100644
--- a/test/src/unit-string-helper.cpp
+++ b/test/src/unit-string-helper.cpp
@@ -155,6 +155,8 @@ TEST_CASE("match-functions") {
 	CHECK( inja::match(" upper(lower()) ", map_regex).type() == inja::Parsed::Function::Upper );
 	CHECK( inja::match("lower(upper(test))", map_regex).type() == inja::Parsed::Function::Lower );
 	CHECK( inja::match("round(2, 3)", map_regex).type() == inja::Parsed::Function::Round );
+	CHECK( inja::match("exists(\"var\")", map_regex).type() == inja::Parsed::Function::Exists );
+	CHECK( inja::match("existsIn(var, \"othervar\")", map_regex).type() == inja::Parsed::Function::ExistsInObject );
 }
 
 TEST_CASE("create-regex-functions") {