diff --git a/bitwise_or.py b/bitwise_or.py
new file mode 100644
index 0000000..97372f1
--- /dev/null
+++ b/bitwise_or.py
@@ -0,0 +1,76 @@
+'''
+bitwise_or
+==========
+
+Merge two or more files by performing bitwise or on their bits.
+
+> bitwise_or file1 file2 --output file3
+'''
+import argparse
+import os
+import sys
+
+from voussoirkit import betterhelp
+from voussoirkit import interactive
+from voussoirkit import operatornotify
+from voussoirkit import pathclass
+from voussoirkit import pipeable
+from voussoirkit import vlogging
+from voussoirkit import winglob
+
+log = vlogging.getLogger(__name__, 'bitwise_or')
+
+CHUNK_SIZE = 2**20
+
+def bitwise_or_argparse(args):
+    patterns = pipeable.input_many(args.files, skip_blank=True, strip=True)
+    files = [file for pattern in patterns for file in winglob.glob(pattern)]
+    files = [pathclass.Path(file) for file in files]
+
+    if len(files) < 2:
+        log.fatal('Need at least two input files.')
+        return 1
+
+    handles = [file.open('rb') for file in files]
+
+    output = pathclass.Path(args.output)
+    if output.is_dir:
+        log.fatal('Output path "%s" is a directory.', args.output)
+        return 1
+
+    if not output.exists:
+        pass
+    elif args.overwrite:
+        pass
+    elif not interactive.getpermission(f'Overwrite "{output.absolute_path}"?'):
+        return 1
+
+    output_handle = output.open('wb')
+    while True:
+        chunk = 0
+        length = 1
+        for handle in handles[:]:
+            read = handle.read(CHUNK_SIZE)
+            length = max(length, len(read))
+            if not read:
+                handles.remove(handle)
+            chunk |= int.from_bytes(read, 'big')
+        if not handles:
+            break
+        output_handle.write(chunk.to_bytes(length, 'big'))
+    pipeable.stdout(output.absolute_path)
+
+def main(argv):
+    argv = vlogging.set_level_by_argv(log, argv)
+
+    parser = argparse.ArgumentParser(description=__doc__)
+
+    parser.add_argument('files', nargs='+')
+    parser.add_argument('--output', required=True)
+    parser.add_argument('--overwrite', action='store_true')
+    parser.set_defaults(func=bitwise_or_argparse)
+
+    return betterhelp.single_main(argv, parser, __doc__)
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))