The 6 Most Popular Sidechains

Cryptocurrency is a borderless way to send money around the globe, but transactions on chain aren’t always ideal. Not only can transactions lag, but sometimes the interoperability you require isn’t available on a certain blockchain. This is where sidechains come in.

Sidechains are blockchains that work on top of blockchains to provide better functionality to users. If you are using blockchain, then you should also be prepared to use a variety of side chains. Keep reading to learn more about the most popular sidechains in blockchain.

What Are Sidechains?

Before we dive in, you may be wondering what a side chain is exactly. Side chains are blockchains that are built to operate on top of other blockchains, and often can’t stand on their own. They are typically built to increase the functionality of the parent blockchain, making it more attractive for users.

Sidechains were introduced by Bitcoin developers in 2014 as a way to solve the scalability issue present in Bitcoin. Almost every large blockchain has at least one sidechain. Sidechains can be critical in the business use of a blockchain. Think of a sidechain a bit like a self-checkout at a grocery store with a cashier—even just a few people using one of the self-checkouts lowers the cashier line for everyone.

**Note that the only large blockchain not to have sidechains is Solana, thanks to the complicated proof-of-history consensus mechanism. This doesn’t mean Solana won’t have sidechains in the future, but for now it is its own thing.

Sidechains vs Layer-2 Solutions

It’s important not to confuse sidechains with layer-2 solutions, which are also built on top of blockchains to increase functionality. The difference, however, lies in the functionality, as side chains function in a far larger capacity than a layer-2 solution. Where layer-2 solutions typically solve a single issue within the blockchain, sidechains can solve many.

Not only that, but sidechains can have multiple purposes, everything from a DEX to a dApp, and more. Layer-2 solutions in and of themselves are a glorified dApp—meaning they will never stand on their own, nor will they expand in the same way a sidechain can. Sidechains typically have their own tokens, many of which grant governance rights to those who hold them.

The 6 Best Sidechains You Should Know

1. Polygon (MATIC)

Perhaps the most famous of all sidechains, Polygon was built on top of Ethereum back when it was still using a proof-of-work consensus mechanism. Ethereum, now one of the faster blockchains, was once much slower; thus, Polygon was created to make transactions faster. Many thought it would fade into the background when Ethereum switched to a proof-of-stake consensus mechanism, but thanks to high gas fees, Polygon is still prevalent as a less expensive way to transact on the Ethereum blockchain and is commonly used by developers.

2. SKALE

In addition to Polygon, Ethereum fans should be aware of SKALE, another Ethereum side chain that launched in 2018. Designed specifically for blockchain developers, users pay a flat monthly fee to use the SKALE side chain during the development process. This allows them to test functionality and interoperability without having to pay for every single small transaction on the blockchain. Use of this blockchain has declined over the years, though some developers still prefer the gasless setup when compared to on-chain development.

3. Rootstock

Rootstock is one of the few Bitcoin sidechains. Unlike Ethereum, which has several, Bitcoin’s placement as “digital gold” generally keeps individuals from needing sidechains when investing in Bitcoin—mostly because they are content with buying  and holding BTC for a long time instead of transacting frequently.

That being said, the Bitcoin blockchain has very little functionality when compared to others, meaning, in theory, it should be big business to have a sidechain for blockchain.

Rootstock was launched in 2018, and aims to bring dApps to the Bitcoin blockchain. It also allows developers to launch dApps on both Bitcoin and Ethereum simultaneously. While this is very cool, Rootstock has yet to make it big—likely because most people are happy with Bitcoin just as it is—without a sidechain.

4. Liquid Network

Another Bitcoin sidechain, we are actually huge fans of the Liquid Network, which allows individuals to transact on the Bitcoin blockchain, but with added security. Launched in 2018, Liquid Network is not only aiming to make Bitcoin transactions fast, but it also offers additional privacy features, obscuring everything from account numbers to asset types traded.

Of course, individuals looking for this level of privacy should also consider Monero, but this sidechain is one of the more useful ones on our list.

5. Gnosis Chain

Back to Ethereum sidechains, Gnosis Chain is a side chain specifically designed to interact with the Ethereum blockchain while offering users lower gas fees. Like SKALE, Gnosis Chain is mostly used for developers, specifically those designing dApps as it lowers the cost of development and testing on the Ethereum blockchain.

First proposed in 2017, Gnosis Chain is still going strong and now has several layer-1 and layer-2 solutions of its own. What is perhaps more interesting though is the fact that Gnosis was started as a blockchain prediction platform in 2015, only to discover that the need was already filled by Augur. Thus, the platform changed over to sidechaining Ethereum in 2017.

6. ZeroCross

ZeroCross is a sidechain proposed for Monero, utilized to further enhance the scalability and privacy of an already extremely private cryptocurrency. Like anything in life, there are still a few ways Monero can be tracked, but thanks to the sidechain ZeroCross, those former methods can be eliminated from possibility.

First proposed in 2022, we were unable to find concrete proof that ZeroCross has been able to work cohesively with the Monero blockchain. This does not mean it won’t be available in the future.

Overall, sidechains are a critical aspect of blockchain, as they improve interoperability while also lowering the cost of doing business. While you don’t have to use sidechains when using cryptocurrency, they are an asset to keep in mind. After all, you never know when you may need to perform multiple costly transactions in a row.