Metachain testnet is now live, with the first subchain deployed for Replay

Theta Labs
Theta Network
Published in
3 min readOct 5, 2022


Theta Metachain has reached an important milestone on the way to production release in December. We’re happy to announce that the Metachain testnet is now live! The first demo subchain has now been deployed to Testnet for use in testing by Replay, the video tracking and payments platform built on Theta. In the coming weeks, Theta Wallet will be updated to allow Theta community developers to test as well, with support and documentation for cross-subchain token transfers.

Theta Metachain is an interconnected network of blockchains, a “chain of chains”. It will allow permissionless horizontal scaling of the Theta blockchain network in order to achieve potentially unlimited transactional throughput and subsecond block finalization time. This enables a customizable, highly scalable blockchain tailored for emerging Web3 businesses in the media and entertainment space.

The Metachain consists of one “main chain” and an unlimited number of “subchains”. Just as “meta-” as a prefix refers to something that transcends or is more comprehensive than the subject, ex. metaphysics describing what exists beyond physics, Theta Metachain refers to an overarching “main chain” above many purpose-specific “subchains”. The “main chain” in this case refers to the existing Theta mainnet. Theta will offer an easy-to-use SDK that developers can quickly use to launch a subchain and plug it into the main chain. Since each subchain can execute transactions independently, this provides a viable path to infinitely scale the processing capacity of the Metachain. The subchain SDK will implement a built-in interchain messaging channel which connects the subchains and the main chain, and thus allows crypto assets like TNT20/721 tokens to flow freely across the chains. The process of creating a subchain is permissionless, meaning that anyone can register and launch a subchain. No approval from Theta Labs is required. You can find the open-source Metachain code on Theta GitHub.

The first demo subchain has now been deployed to Testnet for testing by Replay, the video tracking and payments platform built on Theta. We’ve internally tested transferring assets including TFuel and TNT20/TNT721/TNT1155 tokens back-and-forth between the mainchain and the subchain, validating that the inter-channel communication protocol is working correctly. The subchain produces a new block every 2 seconds, which is much faster than the Theta mainchain. Because of this, transaction finalization on the subchain will also be significantly faster.

The Testnet launch features a new Testnet Metachain Explorer design which showcases the mainchain and the demo subchain:

A newly-designed “Metachain navigation bar” has been added to the explorer pages for users to quickly jump between different chains. Users can simply click on the “Go to chain” drop-down menu on the right to see the list of the chains (see the screenshot below). Users can also click on the “Metachains” menu item to navigate to the Metachain overview page.

The Theta Wallet upgrade for the Metachain Testnet will be ready in the coming weeks. At that time we’ll provide instructions on how to transfer assets cross-chain using the wallet. More documentation for developers will be available at that time, so that anyone can prepare for Metachain release by starting up their own subchain on testnet.

Please note, during the Subchain testing phase we may need to wipe out the Subchain data multiple times and restart the Subchain from genesis.