To piggyback off of Ashwath’s L2 post from yesterday, the demand for L2 blockspace continues to surge upwards. This adoption is clearly evident when monitoring usage metrics such as transaction counts, TVL, security costs, and ultimately profits.

There is no denying that the OP and ARB token airdrops aided in the uptick of activity for their respective networks. However, the continued usage and sustained growth have proven it’s not just a flash in the pan.

Moreover, with the launch of zkSync’s mainnet (Era) last month, accompanied by its speculated upcoming airdrop, it’s no surprise that zkSync has also witnessed an activity surge. In fact, zkSync Era now has the third largest TVL ($260M) of L2s that settle on ETH.

So, of the top 3 L2s by TVL (Arbitrum, Optimism, and zkSync), which is most profitable? To find this, we simply take the spread between the fee revenue generated and the L1 call data security costs (plus verification costs for zkrollups).

Over the past 12 months, Arbitrum has net profits of ~5,200 ETH, which is 80% above that of Optimism. Considering zkSync Era just launched, it doesn’t make sense to include it in this comparison, but for reference, zk has generated ~50 ETH in profit since launch.

So from a raw profit perspective, Arbitrum substantially trumps that of Optimism. But is it simply a product of heightened volume? Yes and no.

Although Arbitrum has 80% higher profits compared to Optimisim, it only has 54% more transaction volume and 28% more revenue. So, in short, Arbitrum is cheaper to transact on, which has led to less revenue on a per tx basis. The answer really lies within the L1 security costs, Arbitrum only has 20% higher security costs in comparison. On a per-transaction basis, Optimism is paying nearly double that of Arbitrum for L1 call data.

The demand for rollups is clear. As the L2 ecosystem continues to evolve and grow, so will its profitability metrics. As for now, Arbitrum is considerably more profitable in comparison to Optimism and zkSync due to higher throughput and cheaper security costs.