Polygon Commit Chain

NinjaWingnut Crypto
6 min readJul 31, 2021


In yesterday’s article about Layer 2 Scaling, I eluded to the fact that Polygon uses it’s own flavor of the plasma framework, and today I am going to explore that a little deeper, because it’s becoming quite a large player, and I think it’s important to understand how some of the core functionality works.

For the usual disclosure, I am not a financial advisor, I don’t even work in finance at all. My day job is as a telecommunications software engineer. Treat everything you read here as some educational resources and not financial advice.


We need to start with a quick refresher of what a sidechain is. They basically run in parallel to the main blockchain, processing transactions and periodically updating the main chain when necessary. They are one of the scaling solutions that is employed, especially on the Ethereum network, and help reduce the number of transactions that get processed on the main blockchain.

They generally have their own consensus mechanism, generally Proof of State (PoS), but really any of them can be used. Funds get moved between the main chain an the sidechains by some kind of bridge, which we’ll cover in more detail below. Once the funds are moved, you can use them with any of the Decentralized Applications (DApps) and smart contracts that have been deployed to the sidechain.

One thing to note, once you move your funds onto a sidechain, you’re now reliant on that blockchain and not the main one. So if you move your funds onto some sketchy sidechain, they can very easily be stolen, so always make sure you are trusting where you are sending your funds, as is the case with everything in crypto, and something I say often, Do You Own Research. This also includes the bridge that you are planning to use to get between the chains.

Polygon Commit Chain

The architecture of the Polygon network has quite a few differences from a standard sidechain, especially in how it leverages the main Ethereum blockchain to provide an extra layer of security that is not a standard part of the framework. Let’s explore some of these features and see just why Polygon is becoming as big as it is.


In most sidechains, the token holders choose only 21 validators to manage the blockchain by staking their tokens in pools on the various nodes. The 21 nodes with the most tokens staked, get to be the validators for the network and generate new blocks and keep the network running. Some even go so far as to have a Proof of Authority (PoA) system where the creators decide the validators themselves and manage the network in a more centralized manner.

On the Polygon network anyone can become a validator. Anyone can just setup a node, stake their Polygon (MATIC) tokens, which is done on the main Ethereum blockchain, and start validating transactions. Having the staking contracts and set of validators maintained on the main chain, allows leveraging it’s security to help control the network.

If a validator starts behaving maliciously on the Polygon network, their stake can be slashed. This can include things like significant downtime, or by double signing transactions, basically anything that a validator node should not be doing.

Heimdall Chain

The Heimdall chain works off the main smart contracts on the Ethereum network that manages all of the staking, It handles checkpoints, and it coordinates validator selection and updating the list. Because this is handled on the main chain, even if all of the validators decided to turn malicious, the community would still have the power to take control back over.

All that would be required would be to redeploy the contracts, and move their staked funds over to the new one, and even go ahead and slash all the bad actors stake as well. This basically helps protect the network from any kind of hostile takeover by a group accumulating a large amount of validator position and then deciding to wreak havoc, because they just get forked out of the equation. And no, that was not a replacement for cursing, I’m talking an actual hard fork, because essentially just moving the network out from under them by changing out the contracts.

Bor Chain

The Bor chain is the more traditional blockchain part of the architecture, in that it is where all the transactions get put together into blocks. The producers of these blocks are a smaller grouping of the validators, which is periodically chosen out at random.

A validator can be chosen to validate blocks on the Bor chain for a set period of time known as a span, which gets allocated out by Heimdall. There is some complicated happenings, but basically all the validators are put into a list based on the number of tokens they have, and given a set number of slots they could get, based on that number. All the possible slots are then put into a list which is randomized, and then the number of needed block producers is popped off the top of that list.

This means that theoretically any validator on the network can be chosen to produce blocks during a span, and of course the more you have staked, the more likely it is that your node gets chosen to create some blocks.


Checkpoints are the other important piece that I mentioned fell under responsibility of the Heimdall chain, but it is important enough to warrant it’s own section, as it’s another part that helps secure the Polygon network by leveraging the main Ethereum blockchain.

Heimdall will aggregate blocks that are being produced on the Bor chain, and periodically produce what is called a merkle root. Without getting too far into the weeds, just consider it a much more intense rollup type of feature where a bunch of transactions are grouped together and only the end states need to get stored on the main chain.

These checkpoints provide finality, and are used along with the main contract deployed on Ethereum to be considered the ultimate truth of the state of the Polygon network.

Ethereum Bridge

In a lot of sidechains, the bridge between the main network and the sidechain is handled by a much smaller group, generally under some kind of Proof of Authority type setup, rather than relying on the validators of the network. This of course is a pretty big security concern, as you have to trust the centralized point to get between the networks.

Polygon provides two separate bridges, the plasma bridge, and the PoS bridge. The plasma bridge is a more secure way to go, as it leverages the underlying security aspects of the plasma framework, but has one very big drawback, and that is that the exit function takes about a week to complete and get your funds back onto the main chain.

The PoS bridge is a much quicker option, and is maintained by a group of validators, stored and controlled on the main Ethereum network, again leveraging additional security by having it managed that way.


I know my focus was on how Polygon interfaces with the Ethereum network, but they are of course now connected to more than just Ethereum, but the differences there is more on the bridge side of things than anything, so it’s not worth muddying the waters by looking at that part of it.

Polygon seems to be a pretty well thought out sidechain, especially when it comes to securing the blockchain, and gives a cheaper way to get access into a lot of popular Ethereum DApps. If the Binance Smart Chain (BSC) is not your thing, but you also don’t want to pay for Ethereum transaction fees, well this might be a good option for you.

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Want some more content right now? Check out some of my previous posts:

Next Level Swaps: SwapSpaceExplained

Layer 2 Scaling
Why Is DeFi Expensive
DeFi Money Markets

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Originally Posted On My Website: https://ninjawingnut.xyz/2021/07/30/polygon-commit-chain/