# Firn's MetaMask Snap

One of Firn's key features is that its privacy is *pluggable*: you can call arbitrary smart contracts privately.

One difficult aspect, though, comes from the problem of assembling calldata. In *normal* (non-private) blockchain interactions, sophisticated front-ends like Uniswap's (or Firn's!) do the job of assembling transaction arguments for you, and also guide you through the process of submitting these to the blockchain.

In the setting where we want to do a complex contract interaction *and* get privacy at the same time, we'd like to still be able to leverage front-ends in order to populate our transactions, as we usually do. On the other hand, using Firn directly for this task—see the [God Mode](/overview/using-firn/god-mode.md) page—has the clear drawback that you have to enter your transaction arguments (or raw calldata) manually, and can't use the target site's web-based interface.

Firn's [*MetaMask Snap*](https://metamask.io/snaps/) offers a way of reconciling these two needs. Using our Snap, arbitrary third-party websites can integrate Firn's privacy functionality directly into their front-ends. Specifically, these applications can populate transaction arguments through a graphical interface, as they usually do, but then directly pipe these into Firn on the user's behalf. This can be viewed as a much-more-direct alternative to using God Mode.

Our Snap is fully working, and is ready for integration today. You can access it [through npm](https://www.npmjs.com/package/@firnprotocol/snap). For a live, hosted example app which *uses* our Snap, check out [tome.fm](https://tome.fm). Tome is, in fact, [open-source](https://github.com/firnprotocol/tome); by inspecting it, anyone interested in integrating Firn's pluggable privacy into *his own* project will find an invaluable template.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.firn.io/developers/firns-metamask-snap.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.