diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 0a3b910b..bf07b26d 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -26,3 +26,11 @@ jobs:
           python-version: ${{ matrix.python-version }}
       - name: Check configuration
         run: make check PIP=pip BUILDBOT=buildbot PYTHON_VERSION=${{ matrix.python-version }}
+      - name: Compare configuration reports
+        run: |
+          # Use the same formatter for both configurations, including older main revisions.
+          python -m utils.config_report -vvv > "$RUNNER_TEMP/branch_report"
+          git fetch --depth=1 origin main
+          git checkout FETCH_HEAD master/
+          python -m utils.config_report -vvv > "$RUNNER_TEMP/main_report"
+          git diff -U10 --color=always --no-index "$RUNNER_TEMP/main_report" "$RUNNER_TEMP/branch_report" || test "$?" -eq 1
diff --git a/Makefile b/Makefile
index 2e643adf..f13f2a1e 100644
--- a/Makefile
+++ b/Makefile
@@ -2,6 +2,7 @@ PYTHON_VERSION=3.13
 SYSTEM_PYTHON=python$(PYTHON_VERSION)
 VENV_DIR=./venv
 REQUIREMENTS=requirements-$(PYTHON_VERSION).txt
+PYTHON=$(VENV_DIR)/bin/python
 PIP=$(VENV_DIR)/bin/pip
 BUILDBOT=$(VENV_DIR)/bin/buildbot
 VENV_CHECK=$(VENV_DIR)/lib/python$(PYTHON_VERSION)/site-packages/buildbot/master.py
@@ -38,6 +39,12 @@ regen-requirements:
 check: $(VENV_CHECK)
 	$(BUILDBOT) checkconfig master
 
+
+## report [OPTS=...] Print out a summary of the current configuration
+.PHONY: report
+report: $(VENV_CHECK)
+	$(PYTHON) -m utils.config_report $(OPTS)
+
 # Management targets
 
 .PHONY: update-master start-master restart-master stop-master
diff --git a/utils/config_report.py b/utils/config_report.py
new file mode 100644
index 00000000..f9b0bd88
--- /dev/null
+++ b/utils/config_report.py
@@ -0,0 +1,146 @@
+import argparse
+import os
+import re
+import shlex
+import shutil
+import sys
+import textwrap
+from collections.abc import Mapping
+from pathlib import Path
+
+
+_COLOR = sys.stdout.isatty() and 'NO_COLOR' not in os.environ
+_WIDTH = shutil.get_terminal_size(fallback=(100, 24)).columns
+_STYLES = {'bold': 1, 'cyan': 36, 'dim': 2}
+
+
+def style(text, name):
+    if not _COLOR:
+        return text
+    return f'\033[{_STYLES[name]}m{text}\033[0m'
+
+
+def format_value(value):
+    # Handle things that look like renderers to avoid memory addresses in output
+    if hasattr(value, 'fn'):
+        name = getattr(value.fn, '__qualname__', type(value.fn).__qualname__)
+        if value.args or value.kwargs:
+            return f'renderer({name}, args={value.args!r}, kwargs={value.kwargs!r})'
+        return f'renderer({name})'
+    return str(value)
+
+
+def print_value(label, value, indent):
+    prefix = (' ' * indent + str(label)).ljust(indent + 12) + '  '
+    available_width = max(20, _WIDTH - len(prefix))
+    text = format_value(value)
+
+    lines = []
+    for paragraph in text.splitlines() or ['']:
+        wrapped = textwrap.wrap(
+            paragraph,
+            width=available_width,
+            break_long_words=False,
+            break_on_hyphens=False,
+        )
+        lines.extend(wrapped or [''])
+
+    print(style(prefix, 'cyan') + lines[0])
+    for line in lines[1:]:
+        print(' ' * len(prefix) + line)
+
+
+def print_detail(label, value, indent=2):
+    heading = ' ' * indent + str(label)
+
+    if isinstance(value, Mapping) and value:
+        print(style(heading, 'cyan'))
+        for key, item in value.items():
+            print_detail(key, item, indent + 2)
+        return
+
+    if isinstance(value, (list, tuple)) and value:
+        if label == 'command':
+            command = shlex.join(format_value(argument) for argument in value)
+            print_value(label, command, indent)
+        elif all(isinstance(item, str) for item in value):
+            print_value(label, ', '.join(value), indent)
+        else:
+            print(style(heading, 'cyan'))
+            for item in value:
+                print_detail('-', item, indent + 2)
+        return
+
+    print_value(label, value, indent)
+
+
+def report(config):
+    parser = argparse.ArgumentParser(description='List configured builders.')
+    parser.add_argument(
+        '-v', '--verbose', action='count', default=0,
+        help='show builder details; repeat to include build steps',
+    )
+    parser.add_argument(
+        '-f', '--filter',
+        help='Only report builders with a matching name',
+    )
+    args = parser.parse_args()
+
+    for builder in sorted(config['builders'], key=lambda b: b.name):
+        if not re.search(args.filter or '.*', builder.name, flags=re.IGNORECASE):
+            continue
+        print(style(builder.name, 'bold'))
+        if not args.verbose:
+            continue
+        print_detail('Factory', type(builder.factory).__name__)
+        for key in (
+            'workernames',
+            'builddir',
+            'tags',
+            'env',
+            'properties',
+            'defaultProperties',
+            'description',
+        ):
+            value = getattr(builder, key)
+            if not value:
+                continue
+            if isinstance(value, list):
+                value = sorted(value)
+            print_detail(key, value)
+        if args.verbose > 1:
+            for step in builder.factory.steps:
+                print(f'    {step.step_class.__name__}')
+                if step.args:
+                    print_detail('args', step.args, indent=6)
+                # Show useful inherited defaults as well as explicit overrides.
+                details = {}
+                if args.verbose > 2:
+                    for key in (
+                        'command', 'env', 'timeout', 'maxTime',
+                        'haltOnFailure', 'flunkOnFailure', 'warnOnFailure',
+                        'alwaysRun',
+                    ):
+                        value = getattr(step.step_class, key, None)
+                        if value is not None:
+                            details[key] = value
+                details.update(step.kwargs)
+                for key, value in details.items():
+                    print_detail(key, value, indent=6)
+        print()
+
+    counts = [
+        f'{len(config[key])} {key}'
+        for key in ('builders', 'workers', 'schedulers')
+    ]
+    totals = 'Totals: ' + ' · '.join(counts)
+    print(style(totals, 'dim'))
+
+
+if __name__ == '__main__':
+    import runpy
+
+    root_dir = Path(__file__) / '..' / '..'
+    master_config = root_dir / 'master' / 'master.cfg'
+
+    report(runpy.run_path(master_config.resolve())['BuildmasterConfig'])