With a market cap of $480 billion, Ethereum (ETH -0.36%) has soared over 540,000% since its 2015 inception -- leaving late investors kicking themselves for not getting in while it was cheaper. 

But the good news is that assets like Solana (SOL -1.02%) and Polkadot (DOT 0.28%) could make great alternatives. Dubbed "Ethereum killers," these blockchains boast smaller market caps and superior scalability, setting them up for explosive long-term growth. 

Flaming stock chart moving upwards.

Image source: Getty Images.

1. Solana 

Up 28% in the last 30 days to a market cap of $60 billion, Solana is rapidly gaining ground among cryptocurrency investors. The programable blockchain allows users to create autonomous programs called decentralized applications (dApps). And it is a top Ethereum alternative because of its smaller valuation and technical innovations.

Solana's advantage comes from its block validation system. Unlike Ethereum, which uses a proof-of-work (PoW) protocol where miners solve puzzles to verify transactions, Solana uses a proof-of-stake (PoS) system. Miners update the blockchain using existing coins -- supported by a proof-of-history (PoH) algorithm that speeds up the process by recording time. 

According to its developers, Solana is the fastest blockchain in the world, capable of processing over 50,000 transactions per second compared to Ethereum's 15 or less. Solana's massive transaction capacity means more dApps will be able to run concurrently without slowing things down -- boosting demand for its native token, SOL, which will be used to pay fees and interact on the network. 

Solana's website lists 500 dApps operating on its blockchain, compared to Ethereum's 2,880 (according to stateofthedapps.com). Ethereum's first-mover advantage and brand recognition help it dominate the space. But Solana's superior functionality positions it to catch up over the long term. 

2. Polkadot 

Started by Ethereum co-founder Gavin Wood, Polkadot boasts a unique approach to dApp development that aims to give developers more freedom. With a scalable design and market cap of just $39 billion, it looks like a good deal relative to larger rivals. 

Polkadot operates two types of blockchains: its primary network called the relay chain, and 100 (this number can be increased as needed) programmable networks called parachains, which can be customized for specific uses while benefiting from the security and technical capabilities of the main chain. 

The parachains can function similarly to dApps, and Polkadot's development team is currently auctioning off parachain slots to private developers who will create their own projects. The auctions are conducted with Polkadot's native token, DOT, which boosts demand for the asset. 

Existing Polkadot parachain projects include decentralized crypto exchange Acala, and Parallel Finance, a lending protocol that allows users to earn interest on their tokens by providing liquidity. The Polkadot network boasts an impressive transaction capacity of 166 per second, which is 11 times higher than Ethereum at 15. 

Betting on fundamentals 

Solana and Polkadot help push blockchain technology forward in scalability, which will help attract dApp development and investor capital over the long term. With relatively modest market caps, both cryptos are excellent alternatives for investors who missed out on Ethereum when it was cheap.