diff --git a/docs/n3/develop/write/update.md b/docs/n3/develop/write/update.md
index 5dcd04b..2393657 100644
--- a/docs/n3/develop/write/update.md
+++ b/docs/n3/develop/write/update.md
@@ -24,7 +24,7 @@ If you want to update the contract later, you must implement the `update` method
 ### Updating the contract
 1. Get the compiled NEF file and Manifest file of the new contract ready
 
-2. Base64-encode the NEF file with the tool like [File to Base64 online](https://www.hitoy.org/tool/file_base64.php)
+2. Base64-encode the NEF file with the tool like [File to Base64 online](https://base64.guru/converter/encode/file)
 
 3. Compress and escape the Manifest file with the tool like [JSON compressed and escaped online](http://www.bejson.com/zhuanyi/)
 
diff --git a/i18n/zh/docusaurus-plugin-content-docs/current/n3/develop/write/update.md b/i18n/zh/docusaurus-plugin-content-docs/current/n3/develop/write/update.md
index c5f52ed..1e88244 100644
--- a/i18n/zh/docusaurus-plugin-content-docs/current/n3/develop/write/update.md
+++ b/i18n/zh/docusaurus-plugin-content-docs/current/n3/develop/write/update.md
@@ -25,7 +25,7 @@ public static void Update(ByteString nefFile, string manifest)
 
 1. 准备好新合约编译后的 NEF 文件和 Manifest 文件
 
-2. 获得 Base64 格式的 NEF，可使用 [文件在线转 Base64](https://www.hitoy.org/tool/file_base64.php)
+2. 获得 Base64 格式的 NEF，可使用 [文件在线转 Base64](https://base64.guru/converter/encode/file)
 
 3. 获得压缩转义的 Manifest，可使用 [JSON在线压缩转义](http://www.bejson.com/zhuanyi/)