diff --git a/README.md b/README.md
index 42aa5f2..196d1c1 100644
--- a/README.md
+++ b/README.md
@@ -24,3 +24,14 @@
      pandoc -f markdown -t gfm > $dir.md
    done
    ```
+## Compare certificates
+
+There is a script `compare_certs.py` that can be used to compare a certificate with other certificates.
+The script generates markdown.
+
+Example usage:
+
+   ```shell
+   poetry run python3 compare_certs.py cacert/root_X0F.crt certum/CA.crt globalsign/root-r6.crt | \
+   pandoc -f markdown -t gfm > compare_root_cas.m
+   ```
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