We all know block explorers are essential public goods for blockchain users. They help both novice users and experienced developers peek under the hood of a blockchain to see and verify on-chain transaction history. 

But what if the on-chain information is only a part of the story? 

While block explorers play a crucial role in the ecosystem, they do not include any details on the ephemeral data layers that impact how transactions reach their final state. This is where mempool explorers come in.

Block Explorers: Seeing the On-Chain Truth

Before we explore what a mempool explorer is and why it’s needed, let's review the role that block explorers play in helping democratize access to on-chain data. 

The Role of Block Explorers

One day you might tell your grandchild that the only way to verify the first transactions on Ethereum was to run your own node - downloading the entire state of the chain to your desktop. Anyone who has done that is grateful for the experience of a block explorer. Block explorers remove the technical barrier of running your own node and make on-chain blockchain data readily available to the masses. They also provide a high degree of repeatability, allowing developers to simply point their dapps to a reliable explorer instead of reinventing the wheel.

Block Explorer: Defining Characteristics

• Focus: Primarily deals with on-chain data, information already confirmed and stored permanently on the blockchain.
  
  
• Data Type: Provides access to historical information, including transaction history, block details (hash, height, timestamp), wallet balances, and network statistics. Data is stored on all operating nodes and can be accessed at any time.
  
  
• Update Frequency: Relatively static, updates occur when new blocks are verified and added to the chain.
  
  
• Use Case: Ideal for tasks like verifying transactions, tracking wallet activity, and analyzing historical on-chain blockchain data.
  
  
• Example: Etherscan, Blockscout 

Ephemeral Data Sets: What Are They?

Block explorers are fantastic for on-chain data, but there's a whole other world happening before transactions are confirmed on-chain: the mempool. This ephemeral data layer holds unconfirmed transactions waiting to be included in a block. Just like with block explorers, not everyone has the technical chops to delve into the mempool.

Here's why a mempool explorer is just as crucial as its block-focused counterpart:

• Understanding the Why Behind the What: Mempool explorers remove the technical barrier, making pre-chain data readily available. You can see what happened with transactions, not just that they happened. This allows anyone to understand why a transaction might be delayed or stuck and track every step of a transaction's history. For example if a transaction is stuck was it a nonce issue, gas issue, something else? You can only answer these questions through the observability into the mempool layer.
  
  
• Transparency is Key: With increasing regulatory scrutiny, a mempool explorer demonstrates an ecosystem’s commitment to transparency. Institutional investors, regulators, and law enforcement can see what's happening within the ecosystem.
  
  
• Tracing Transactions on Each Layer: The blockchain ecosystem is booming, with Layer 2 (L2) solutions exploding and Layer 3 (L3) protocols emerging. But with this growth comes a challenge: tracking transactions across this intricate web of interconnected chains. Mempool explorers are critical for backend developers to troubleshoot issues and help ensure the orderly operation of their chains. Instead of having to decode transactions manually, the explorers do the heavy lifting for the entire ecosystem. 

Mempool explorers offer a crucial vantage point, revealing the current state of the transaction and potential reasons for issues or delays. They empower developers to pinpoint bottlenecks, streamline network performance, and maintain the seamless operation of L2/L3 protocols. 

Each protocol is unique and mempool explorers can cater to this differentiation. For example, on Ethereum, private transactions (transactions that are sent directly to block builders and never enter the public mempool) have increased in prominence and are impossible to identify with purely on-chain analytics. With a mempool explorer, however, one can easily filter for private transactions because of the added visibility into the mempool. 

Like block explorers, mempool explorers provide a high degree of repeatability, allowing developers to simply point their dapps to a reliable mempool explorer instead of reinventing the wheel. But unlike block explorers, the mempool is ephemeral and cannot be recreated—if nothing is capturing the data, the data is lost forever.

Mempool Explorer: Defining Characteristics

• Focus: Primarily deals with pre-chain data residing in the mempool, a temporary holding area for unconfirmed transactions.
  
  
• Data Type: Provides access to real-time and dynamic information, including transaction fees, transaction status (pending, confirmed, rejected), and mempool size. If not captured, data is lost forever.
  
  
• Update Frequency: Highly dynamic, constantly updating as transactions enter and leave the mempool.
  
  
• Use Case: Ideal for tasks like monitoring transaction confirmation times, identifying potential bottlenecks, and gaining insights into network activity.
  
  
• Example: Ethernow.xyz

The Future is Multi-Explorer

Blockchains are complex beasts, and explorers will increasingly focus on different aspects of the chain to give users and developers the best experience possible. Here's why the future holds multiple explorer classes:

• Streaming vs. Static: The mempool is a dynamic, ever-changing stream of data. Blockchains, on the other hand, are static ledgers with discrete entries. These require completely different architectures to run efficiently. A block explorer is a static explorer, while a mempool explorer is dynamic.
  
  
• Confirming vs Debugging: Block explorers confirm what happened, mempool explorers tell you why. While block explorers are fantastic for confirming a transaction landed on-chain, mempool explorers facilitate troubleshooting, provide insights into optimizing performance, and confirm smooth operations.

As blockchains and data availability layers evolve, expect to see a diverse ecosystem of explorers catering to different needs. Different types of explorers demand different classes of infrastructure. Block explorers require deep expertise in indexing and managing large data sets. While mempool explorers require deep expertise in streaming data, storing data, and real-time systems. For anyone who wants to ensure access to ephemeral data layers, adding a mempool explorer to your ecosystem can help to improve how developers, researchers, and other actors engage with your chain. 

If you are part of an L1, L2, or Protocol that wants to ensure your ephemeral data is captured and accessible as a public good for developers to attract and accelerate adoption, get in touch with Blocknative.