diff --git a/bib_add_keyword.py b/bib_add_keyword.py
new file mode 100644
index 0000000..7540d55
--- /dev/null
+++ b/bib_add_keyword.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8; mode: python -*-
+
+"""This script adds one or more keywords to all entries of a bibtex file.
+
+This is a feature that surprisingly no bibtex editor offers."""
+
+__version__ = "1.0"
+__date__ = "20181017"
+__author__ = "kthoden@mpiwg-berlin.mpg.de"
+
+import argparse
+import logging
+import bibtexparser
+from bibtexparser.bwriter import BibTexWriter
+from bibtexparser.bibdatabase import BibDatabase
+
+logging.basicConfig(level=logging.INFO, format=' %(asctime)s - %(levelname)s - %(message)s')
+
+def add_keyword(entry, keyword):
+    """Add keyword to bibtex entry"""
+
+    try:
+        entry_keyword = entry["keyword"]
+        # bibtex parser uses keyword rather than keywords, we correct this here
+        if entry["keyword"]:
+            entry["keywords"] = entry["keyword"]
+            entry.pop("keyword")
+    except KeyError as err:
+        print("no keyword found", err)
+    try:
+        entry_keywords = entry["keywords"]
+        # entry["keywords"] = args.keyword
+        all_keywords = [x.strip() for x in entry_keywords.split(",")]
+        print(all_keywords)
+        if keyword in all_keywords:
+            logging.info("Keyword %s already in.", keyword)
+        else:
+            logging.info("Adding keyword %s.", keyword)
+            entry["keywords"] = entry_keyword + "," + keyword
+    except KeyError as err:
+        logging.info("%s, Found no keywords, adding one.", err)
+        entry["keywords"] = keyword
+
+    return entry
+# def add_keyword ends here
+
+def main():
+    """The main bit"""
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-k", "--keyword", help="Assign one or more\
+    keywords. Several keyword must be separated by ',' and wrapped in\
+    quotes.")
+    parser.add_argument("bibtexfile", help="A text file containing a formatted bibliography.")
+    args = parser.parse_args()
+
+    with open(args.bibtexfile) as btf:
+        btb = bibtexparser.load(btf)
+
+    bib_database = BibDatabase()
+    db_list = []
+
+    for entry in btb.entries:
+        new_keywords = args.keyword.split(",")
+        print(new_keywords)
+        for keywords in new_keywords:
+            newentry = add_keyword(entry, keywords)
+
+        db_list.append(newentry)
+
+    bib_database.entries = db_list
+
+    bibfile_path = args.bibtexfile.replace(".bib", "-addedkeyword.bib")
+
+    writer = BibTexWriter()
+    # indent entries with 4 spaces instead of one
+    writer.indent = '    '
+    with open(bibfile_path, 'w') as fakebibfile:
+        fakebibfile.write(writer.write(bib_database))
+    logging.debug("Added keywords to entries and wrote %s.", bibfile_path)
+# def main ends here
+
+
+if __name__ == '__main__':
+    main()
+# finis