diff --git a/src/imcflibs/strtools.py b/src/imcflibs/strtools.py
index d522c46..b65a333 100644
--- a/src/imcflibs/strtools.py
+++ b/src/imcflibs/strtools.py
@@ -175,3 +175,44 @@ def pad_number(index, pad_length=2):
     '0042'
     """
     return str(index).zfill(pad_length)
+
+
+def text_in_last_bracket_group(text):
+    """Return the content of the last balanced square-bracket group.
+
+    Parameters
+    ----------
+    text : str
+        The input string to search for the last balanced square-bracket group.
+
+    Returns
+    -------
+    str or None
+        The content of the last balanced square-bracket group, or None if no
+        such group exists.
+
+    Examples
+    --------
+    >>> text_in_last_bracket_group("foo[bar]baz")
+    'bar'
+    >>> text_in_last_bracket_group("foo[bar[baz]qux]")
+    'bar[baz]qux'
+    >>> text_in_last_bracket_group("foo[]bar")
+    ''
+    >>> text_in_last_bracket_group("foobar")
+    None
+    """
+    depth = 0
+    end = None
+
+    for index in range(len(text) - 1, -1, -1):
+        if text[index] == "]":
+            if end is None:
+                end = index
+            depth += 1
+        elif text[index] == "[":
+            depth -= 1
+            if depth == 0:
+                return text[index + 1 : end]
+
+    return None
diff --git a/tests/test_strtools.py b/tests/test_strtools.py
index 87cf17c..be73293 100644
--- a/tests/test_strtools.py
+++ b/tests/test_strtools.py
@@ -1,13 +1,17 @@
 """Tests for `imcflibs.strtools`."""
 # -*- coding: utf-8 -*-
 
-import pytest
 import os
 
-from imcflibs.strtools import _is_string_like
-from imcflibs.strtools import filename
-from imcflibs.strtools import flatten
-from imcflibs.strtools import strip_prefix
+import pytest
+
+from imcflibs.strtools import (
+    _is_string_like,
+    filename,
+    flatten,
+    strip_prefix,
+    text_in_last_bracket_group,
+)
 
 
 def test__is_string_like():
@@ -37,3 +41,51 @@ def test_strip_prefix():
     """Test `strip_prefix()`."""
     assert strip_prefix("foobar", "foo") == "bar"
     assert strip_prefix("foobar", "bar") == "foobar"
+
+
+def test_text_in_last_bracket_group_basic():
+    """Test `text_in_last_bracket_group()` with a single bracket group."""
+    assert text_in_last_bracket_group("foo[bar]baz") == "bar"
+
+
+def test_text_in_last_bracket_group_multiple():
+    """Test `text_in_last_bracket_group()` with multiple bracket groups."""
+    assert text_in_last_bracket_group("foo[bar]baz[qux]") == "qux"
+
+
+def test_text_in_last_bracket_group_nested():
+    """Test `text_in_last_bracket_group()` with nested bracket groups."""
+    assert text_in_last_bracket_group("foo[bar[baz]qux]") == "bar[baz]qux"
+
+
+def test_text_in_last_bracket_group_empty():
+    """Test `text_in_last_bracket_group()` with an empty bracket group."""
+    assert text_in_last_bracket_group("foo[]bar") == ""
+
+
+def test_text_in_last_bracket_group_no_brackets():
+    """Test `text_in_last_bracket_group()` with no bracket groups."""
+    assert text_in_last_bracket_group("foobar") is None
+
+
+def test_text_in_last_bracket_group_empty_string():
+    """Test `text_in_last_bracket_group()` with an empty string."""
+    assert text_in_last_bracket_group("") is None
+
+
+def test_text_in_last_bracket_group_only_brackets():
+    """Test `text_in_last_bracket_group()` with only brackets."""
+    assert text_in_last_bracket_group("[foo]") == "foo"
+
+
+def test_text_in_last_bracket_group_deeply_nested():
+    """Test `text_in_last_bracket_group()` with deeply nested brackets."""
+    assert text_in_last_bracket_group("foo[bar[baz[qux]]]") == "bar[baz[qux]]"
+
+
+def test_multi_series_files():
+    """Test `text_in_last_bracket_group()` with multiple series files."""
+    filename = "ChannelSD - DAPI 20x,SD - GFP 20x,SD - Cy3 20x,SD - Cy5 20x_Seq0002.nd2"
+    input = "%s [%s (series 1)]" % (filename, filename)
+    expected = "%s (series 1)" % filename
+    assert text_in_last_bracket_group(input) == expected