# Protobuf > Decode Protobuf HTTP and HTTPS requests, responses, and WebSocket messages in Proxyman with a .desc file descriptor and a Message Type rule. ## 1. Protobuf * Proxyman macOS can decode the Protobuf body of your HTTP/HTTPS requests and responses with a given Protobuf desc file * Decode Protobuf binary and show it as plain text * Supports a Single Message or multiple Delimited Messages in a single Protobuf binary * Import a desc file and read all its Message Types to decode Protobuf binary * Decode [Protobuf from Websocket](https://proxyman.com/docs/advanced-features/websocket#websocket-with-protobuf-payload) ![Proxyman shows a raw Protobuf request body next to the same body decoded as JSON](https://proxyman.com/docs/assets/Screen_Shot_2020-04-25_at_21_32_54.png) ## 2. Protobuf File Descriptor (\*.desc) Proxyman requires a File Descriptor (\*.desc) to properly parse the Protobuf Data. There are a few ways to get the File Descriptor: ### 1. Ask your colleagues. If your company uses Protobuf, there's a good chance that your colleagues already have this file, especially the Backend and Frontend teams. It might be one or multiple descriptor files. ### 2. Generate from \*.proto file If you have many \*.proto files, you can generate one \*.desc file with the following command. ```bash # Install protobuf cli if need brew install protobuf # Create `input` folder on the Desktop # Copy all proto files to the `input` folder # Generate 1 descriptor file with multiple proto files protoc --descriptor_set_out=output.desc --include_imports -I=/Users//Desktop/input /Users//Desktop/input/*.proto # Done # output.desc ``` Once you have the Descriptor File, import it to Proxyman: * **Tools** menu -> **Protobuf…** -> click the **Protobuf Schema...** button * Click the **+** button and select the **output.desc** file > **Note:** Proxyman 3.6.0+ only accepts **File Descriptor (\*.desc)** for better Protobuf parsing. > > If you have **\*.proto** files, you can convert them to **\*.desc**. See [Generate from \*.proto file](#2-generate-from-proto-file) above. > **Note:** Proxyman automatically imports all common types from **Google Protobuf**, such as Timestamp, Struct, Value, Enum, Method, etc. > > Proxyman supports both **proto2** and **proto3** syntax. [Read more](https://developers.google.com/protocol-buffers/docs/proto3) ## 3. Protobuf Config Before using Protobuf, you have to set which Message Type Proxyman should use to parse the Protobuf data. The following table describes the settings: | Name | Description | | ----------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Schema | Add a `.desc` file if needed | | Message Type | The Class name of the root object in Protobuf binary. **Must include Package name** | | Payload Type: **Auto** | Auto detect if the Protobuf Binary is encoded as a Single Message or [Delimited Message](https://developers.google.com/protocol-buffers/docs/techniques#streaming) | | Payload Type: **Single Message** | Single Message in a Protobuf Binary | | Payload Type: **Delimited List** | Multiple Messages in a Protobuf Binary (Length-Prefix) | ![Proxyman Protobuf Settings rule with matching rule, Add Schema, Message Type and Payload Type options](https://proxyman.com/docs/assets/Screenshot%202026-01-31%20at%2010.04.50.png) _Decode Protobuf HTTPS Response with Proxyman_ ## 4. How to use? There are **two** ways to parse Protobuf properly with named fields: * Define Protobuf Rules * Read from Content-Type Header ### 4.1 Define Protobuf Rule 1. Your Protobuf request should have a Content-Type header: `Content-Type: application/x-protobuf` or `Content-Type: application/protobuf` 2. Proxyman detects the Protobuf payload and shows a warning that it can't parse it properly because the message type is missing. Click **Add** to open Protobuf Settings. Alternatively, you can right-click on your request -> **Tools** -> **Protobuf…** ![Proxyman Protobuf request body with a Missing Message Type warning, an Add button and numbered fields without names](https://proxyman.com/docs/assets/Screen_Shot_2020-04-25_at_21_56_19.png) 3\. In the Protobuf rule window, select the Message Type for this Request/Response (add a desc file if needed). > **Note:** If the Request and Response use different Protobuf Message Types, select the \`Use different Message Type for Request / Response\` checkbox. 4\. Click **Add** and see the body in JSON format. ### 4.2 Read from Content-Type Header You can **dynamically** provide the Protobuf Config from `Content-Type` For example: Your `Content-Type` in the Request or Response might look like: `Content-Type: application/x-protobuf; messageType="tutorial.Address"; delimited=true` `Content-Type: application/x-protobuf; messageType="com.proxyman.User"; delimited=false` This tells Proxyman the Message Type and the payload encoding of the Protobuf body. ## 5. ✅ Protobuf With Websocket (from macOS 6.5.0 or later) * Decode a single binary WebSocket frame: Read [websocket.md](https://proxyman.com/docs/advanced-features/websocket) * You can create a Protobuf rule for WebSocket. Use the Request Message Type for client messages, and the Response Message Type for server messages. ## 6. Troubleshooting ### 6.1 Some name fields are missing Some field names can be missing when their definitions are not in your Protobuf File Descriptor. Your descriptor might be out of date. **Solution**: * Remove the old Protobuf Schema and add the latest descriptor file from your server. * If you're using Proxyman 3.5.2 or older, please update to Proxyman 3.6.0 or later. Then, use File Descriptor (\*.desc) for better results. ## Learn more * [How to capture WebSocket and decode Protobuf message](https://proxyman.com/posts/how-to-capture-websocket-with-protobuf-message) * [Proxyman vs mitmproxy: Decode Protobuf WebSocket Messages](https://proxyman.com/posts/2026-07-21-Proxyman-vs-mitmproxy-Protobuf-WebSocket)