This site aims to be a comprehensive guide to Frida. We’ll cover topics such as doing interactive function tracing from the command-line, building your own tools on top of Frida’s APIs, and give you some advice on participating in the future development of Frida itself.

So what is Frida, exactly?

It’s Greasemonkey for native apps, or, put in more technical terms, it’s a dynamic code instrumentation toolkit. It lets you inject snippets of JavaScript into native apps on Windows, Mac, Linux, iOS and Android. Frida also provides you with some simple tools built on top of the Frida API. These can be used as-is, tweaked to your needs, or serve as examples of how to use the API.

Why do I need this?

Great question. We’ll try to clarify with some use-cases:

  • There’s this new hot app everybody’s so excited about, but it’s only available for iOS and you’d love to interop with it. You realize it’s relying on encrypted network protocols and tools like Wireshark just won’t cut it. You pick up Frida and use it for API tracing.
  • You’re building a desktop app which has been deployed at a customer’s site. There’s a problem but the built-in logging code just isn’t enough. You need to send your customer a custom build with lots of expensive logging code. Then you realize you could just use Frida and build an application- specific tool that will add all the diagnostics you need, and in just a few lines of Python. No need to send the customer a new custom build - you just send the tool which will work on many versions of your app.
  • You’d like to build a Wireshark on steroids with support for sniffing encrypted protocols. It could even manipulate function calls to fake network conditions that would otherwise require you to set up a test lab.
  • Your in-house app could use some black-box tests without polluting your production code with logic only required for exotic testing.

Why a Python API, but JavaScript debugging logic?

Frida’s core is written in C and injects Google’s V8 engine into the target processes, where your JS gets executed with full access to memory, hooking functions and even calling native functions inside the process. There’s a bi-directional communication channel that is used to talk between your app (Python?) and the JS running inside the target process.

On top of this C core there are multiple language bindings, e.g. Python, Node.js, .NET, Qml, etc., and it is very easy to build additional bindings for other languages and environments.

ProTips™, Notes, and Warnings

Throughout this guide there are a number of small-but-handy pieces of information that can make using Frida easier, more interesting, and less hazardous. Here’s what to look out for.

ProTips™ help you get more from Frida

These are tips and tricks that will help you be a Frida wizard!

Notes are handy pieces of information

These are for the extra tidbits sometimes necessary to understand Frida.

Warnings help you not blow things up

Be aware of these messages if you wish to avoid certain death.

If you come across anything along the way that we haven’t covered, or if you know of a tip you think others would find handy, please file an issue and we’ll see about including it in this guide.