diff --git a/dnsapi.md b/dnsapi.md
index 83fc535..e24c8e4 100644
--- a/dnsapi.md
+++ b/dnsapi.md
@@ -2732,6 +2732,26 @@ The `cPanel_Username`, `cPanel_Apitoken` and `cPanel_Hostname` will be saved in
 
 Please report any issue to [https://github.com/acmesh-official/acme.sh/issues/3732](https://github.com/acmesh-official/acme.sh/issues/3732)
 
+## 137. Use ISPMan domain API
+
+The `dns_ispman.sh` api Adds & Deletes domain TXT records by authenticating into the [ISPMan](http://ispman.sourceforge.net/) Customer Control Panel and executing HTTP POST & GET requests.
+
+The `dns_ispman.sh` api requires your `<domain>` and `<passwd>` for authentication:
+```sh
+export ISPMan_Username=<domain>
+export ISPMan_Password=<passwd>
+```
+
+The `ISPMan_Username` and `ISPMan_Password` will be saved in `$LE_WORKING_DIR/account.conf` and will be reused for certificate renewals.
+
+Ok, let's issue a cert:
+
+```sh
+acme.sh --issue --dns dns_ispman -d example.com -d *.example.com
+```
+
+Please report bugs to [https://github.com/acmesh-official/acme.sh/issues/3751](https://github.com/acmesh-official/acme.sh/issues/3751)
+
 # Use custom API
 
 If your API is not supported yet, you can write your own DNS API.