While major cryptocurrencies like Bitcoin and Ether and popular meme coins like Dogecoin, and Shiba Inu tend to draw most of the headlines and the lion's share of trader attention, there are now more than 18,000 cryptocurrencies. Some deserve their obscurity, but others could be golden investing opportunities. Here are three cryptocurrencies you've probably never heard of that could be hidden gems.

1. Filecoin

With the largest market cap on this list at roughly $3.6 billion, Filecoin (FIL -2.91%) is not your traditional cryptocurrency. It runs on a peer-to-peer network that streamlines data storage. Users on the network provide the extra storage space on their own devices to securely store other people's data, and are compensated for doing so in Filecoins. The network offers better prices for this distributed cloud storage than regular data-storage companies. With different kinds of providers offering different storage options, customers of the network can pick which combination of redundancy, access speed, and cost best meets their needs.

Obviously, a lot will need to happen for these networks to really become sustainable, but I see networks that apply blockchain technology outside the payments realm to be one area of the blockchain universe that presents lots of differentiation and potential.

Person looking into a blinding light with different shades of Orange around it.

Image source: Getty Images.

2. Harmony One

Harmony (ONE -2.70%) is a relatively new blockchain network with a $1.4 billion market cap. From a technical standpoint, it's an extremely solid network. Harmony believes it has solved many of the issues that have prevented other blockchain networks from successfully scaling, avoiding network congestion problems while also maintaining the decentralization aspect that is key to blockchains' appeal. It utilizes a technique called sharding, which breaks its network into multiple groups of validators working with subsets of the blockchain database to approve transactions and create new blocks. It's the system that many blockchain networks, including Ethereum, are in the process of upgrading to.

Harmony can process 2,000 transactions per second on its network, which is similar to the number that Visa can handle. But Harmony believes its network could one day have the capacity to process 10 million transactions per second. Harmony also operates on a proof-of-stake concept to create new blocks, which involves having validators stake tokens to validate transactions. This is much more energy-efficient than the proof-of-work mining concepts that blockchain networks like Bitcoin started on, which use lots of computing power to solve cryptographic puzzles. All of these components have enabled Harmony to keep its "gas fees" (the cost of completing transactions) low compared to other networks.

3. Zcash

With a market cap of $2.1 billion, Zcash (ZEC -1.59%) is a cryptocurrency that runs on a blockchain network that focuses on privacy. When the first blockchain networks were developed, one key goal was to create an inclusive system that allowed anybody with internet access to send and receive money. Another was to create a decentralized system so that no single authority would have too much power over the transfer of money on the network. But since a blockchain is by its very nature a public ledger, it's not possible to fully shield transactions made on one. Sure, they can be hard to trace, but they are out there for anyone to find.

Zcash has created a network where users can initiate transactions publicly or privately. Users can do this by using either a private "Z-address" for a transaction or a public "T-address." All of the transactions are still visible on the public ledger, but transactions between two Z-addresses do not show the transaction amounts or memos, which are encrypted. Z-addresses and T-addresses can also send transactions between one another. For users who value privacy, Zcash is an appealing option. Interestingly, the maximum number of Zcash tokens that can ever be created is 21 million -- a ceiling similar to that of Bitcoin.