diff --git a/README.md b/README.md
index de792ba..f4d7363 100644
--- a/README.md
+++ b/README.md
@@ -1642,6 +1642,16 @@ which will halt execution.
   characters. For example, `choose('64', HEX)` will generate a random
   64-character lowercase hex string.
 
+#### Datetime
+
+- `datetime(format)`<sup>master</sup> - Return local time with `format`.
+- `datetime_utc(format)`<sup>master</sup> - Return UTC time with `format`.
+
+The arguments to `datetime` and `datetime_utc` are `strftime`-style format
+strings, see the
+[`chrono` library docs](https://docs.rs/chrono/latest/chrono/format/strftime/index.html)
+for details.
+
 #### Semantic Versions
 
 - `semver_matches(version, requirement)`<sup>1.16.0</sup> - Check whether a
diff --git a/src/function.rs b/src/function.rs
index 9226762..dbce934 100644
--- a/src/function.rs
+++ b/src/function.rs
@@ -47,6 +47,8 @@ pub(crate) fn get(name: &str) -> Option<Function> {
     "config_local_directory" => Nullary(|_| dir("local config", dirs::config_local_dir)),
     "data_directory" => Nullary(|_| dir("data", dirs::data_dir)),
     "data_local_directory" => Nullary(|_| dir("local data", dirs::data_local_dir)),
+    "datetime" => Unary(datetime),
+    "datetime_utc" => Unary(datetime_utc),
     "encode_uri_component" => Unary(encode_uri_component),
     "env" => UnaryOpt(env),
     "env_var" => Unary(env_var),
@@ -235,6 +237,14 @@ fn dir(name: &'static str, f: fn() -> Option<PathBuf>) -> FunctionResult {
   }
 }
 
+fn datetime(_context: Context, format: &str) -> FunctionResult {
+  Ok(chrono::Local::now().format(format).to_string())
+}
+
+fn datetime_utc(_context: Context, format: &str) -> FunctionResult {
+  Ok(chrono::Utc::now().format(format).to_string())
+}
+
 fn encode_uri_component(_context: Context, s: &str) -> FunctionResult {
   static PERCENT_ENCODE: percent_encoding::AsciiSet = percent_encoding::NON_ALPHANUMERIC
     .remove(b'-')
diff --git a/tests/datetime.rs b/tests/datetime.rs
new file mode 100644
index 0000000..5092cbe
--- /dev/null
+++ b/tests/datetime.rs
@@ -0,0 +1,27 @@
+use super::*;
+
+#[test]
+fn datetime() {
+  Test::new()
+    .justfile(
+      "
+        x := datetime('%Y-%m-%d %z')
+      ",
+    )
+    .args(["--eval", "x"])
+    .stdout_regex(r"\d\d\d\d-\d\d-\d\d [+-]\d\d\d\d")
+    .run();
+}
+
+#[test]
+fn datetime_utc() {
+  Test::new()
+    .justfile(
+      "
+        x := datetime_utc('%Y-%m-%d %Z')
+      ",
+    )
+    .args(["--eval", "x"])
+    .stdout_regex(r"\d\d\d\d-\d\d-\d\d UTC")
+    .run();
+}
diff --git a/tests/lib.rs b/tests/lib.rs
index 42b3aff..292482f 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -47,6 +47,7 @@ mod completions;
 mod conditional;
 mod confirm;
 mod constants;
+mod datetime;
 mod delimiters;
 mod directories;
 mod dotenv;