How to open a .pb file (Windows, Mac, Linux)

Q: Why can't I open my .pb file?

Usually your computer lacks an app that understands Protobuf. Install one of the apps listed here, or convert the file to a more common format.

Q: Why does my .pb file look like random bytes?

By design. Protobuf stores only field numbers and packed values, no names or structure markers, so the .proto definition is required to interpret it.

A .pb file is a Protocol Buffers Binary Data. If double-clicking does nothing, your computer simply does not have an app that reads Protobuf yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .pb file step by step

Confirm the file really is a .pb. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with protoc (with the .proto schema) or Python (protobuf library).
On Mac, use protoc or Python (protobuf library).
On Linux, try protoc or Python (protobuf library).
Still stuck? Convert the .pb to json (via schema), which opens more widely.

Best apps to open .pb files

Windows

protoc (with the .proto schema)
Python (protobuf library)

macOS

protoc
Python (protobuf library)

Linux

protoc
Python (protobuf library)

Before you open it: Safe as data; a .pb file does not execute. As with any parser input, decode untrusted files with a current protobuf library.

Frequently asked questions

Why can't I open my .pb file?

Almost always because no installed app understands Protobuf. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I open a .pb file?

With its schema: protoc --decode=package.Message schema.proto < file.pb prints it as text. Without a schema, protoc --decode_raw shows field numbers and raw values.

Why does my .pb file look like random bytes?