Zcash Elastic Subnet Bridge on Avalanche

Announcing ZavaX Oracle

To demonstrate our completion of Milestone 1 of the Zcash Elastic Subnet Bridge on Avalanche, red·dev is excited to announce ZavaX Oracle! Along with our first deliverable, we have decided to name our project ZavaX. We like this name because it is short and snappy, it pays homage to both Zcash and Avalanche, and the capital X symbolizes a crossing or bridge.

The Deliverable

Deliverable 1.1: Preliminary PoC that supports querying testnet Zcash transactions from a testnet Avalanche subnet with a CLI, published on Github and with a one-node subnet on the Avalanche testnet.

The ZavaX Oracle exceeds what is required for this deliverable in three ways:

  • In addition to providing a command-line interface, we are also providing a simple web-based GUI, to make it easy for more people to try it out.
  • Instead of querying transactions on the Zcash testnet, we are querying full blocks of transactions from the Zcash mainnet, as these pertain to Zcash users’ daily lives.
  • Instead of using a one-node Avalanche subnet, the ZavaX subnet contains three nodes, allowing for us to test consensus mechanisms, to illustrate the utility of multiple redundant endpoints, and to increase fault-tolerance.


The website, located at https://zavax-oracle.red.dev, is easy to use. We recommend using Brave or Chrome. Just select one of the three ZavaX subnet nodes to be your endpoint (where you are submitting your request), enter the block height of a block in the Zcash blockchain (between 1 and about 2156229) that contains the transaction that you are interested in viewing, and press Submit to ZavaX. The website will then send the request to the node on the ZavaX subnet that you selected. There are two possibilities of what will happen next.

  1. If the Zcash block has previously been added to the ZavaX subnet’s chain, the node will respond with the contents of the block. Below the Response box, you can see what ZavaX block was used.
  2. If the block has not yet been added, the node will initiate a request to add the Zcash block you requested to the ZavaX subnet’s chain, and a consensus conversation will take place between the subnet’s nodes. The website will wait a few seconds for the consensus conversation to finish and then will ask for the block again. By this time, the ZavaX nodes should have reached consensus and added your Zcash block to the ZavaX subnet’s chain, so the node will respond with the Zcash block’s contents.

You may be surprised at how quickly this happens. Avalanche consensus is fast. On top of that, only three nodes need to reach consensus which only takes milliseconds. (Avalanche consensus scales logarithmically, so even with thousands of nodes, it will still only take about a second.)

Note 1: The ZavaX Oracle subnet is running on the Avalanche Fuji testnet, and it is performing queries only, so no gas is required.

Note 2: This is proof-of-concept software, and from time to time, it may not function perfectly. We are testing new infrastructure and new code, and we are building on top of brand new features of Avalanche. As you probably know, with software, “brand new” has its downsides. Please report any problems you encounter to us, and we will resolve them as quickly as possible.

For Techies

If you would like to try this out yourself from the command line, you can use the curl command in the Request box. You will need to grab a copy of the SSL cert for this to work and add its path to your curl command (it is available in the GitHub repo).

There is a link on the website to the source code on GitHub. The code, which is based on examples provided by Ava Labs, can also illustrate to other Avalanche subnet builders about how to build a basic non-EVM subnet.

In the next few months, we will be performing stress tests on the ZavaX subnet, for instance monitoring behavior when validators expire or behave in a byzantine manner. We will announce some of these tests here so that you can participate.

* * *

We are happy to have reached this milestone. This seemingly simple project has allowed the red·dev team to familiarize ourselves with most of the important pieces of technology that we will combine to build this bridge—from the resources Ava Labs provides, to the Zcash chain and Zcashd, to our first non-EVM subnet, and so on.

Our next step is to create the specification for the bridge itself. We intend to proceed carefully; we are building a bridge to last. It seems that with each passing week, another bridge fails, so we are wary. However, just as blockchains can stand the test of time, so can bridges with the proper safeguards.

It is also important for the long-term health of the ZavaX technology to establish business partnerships, so please consider this forum post an open solicitation to other businesses to join with us around ZavaX—whether to create an oracle subnet on Avalanche, or to integrate with the ZavaX bridge we are building, or in other ways that we have not yet imagined.

We are honored to have this opportunity to connect two of our favorite blockchains! Thank you @ZcashGrants for the funding. Also thank you to the Ava Labs developer relations team for your support. It is also humbling to see on Twitter the founders of both Zcash and Avalanche taking an interest in our shared success.