Blockscout - Rootstock Case Study

It was mid 2023, Bitcoin was holding steadyish in the 30K range, and a handful of forward-thinking projects were busy scaling Bitcoin. State channels used by the Lightning Network enabled instant and low-fee payments between parties but didn’t extend Bitcoin’s functionality beyond basic transfers. Bitcoin sidechains introduced more advanced functionality, like smart contract programmability and DeFi protocol development, and Rootstock was (and remains) the leading Bitcoin sidechain solution.

Originally ideated in 2015, Rootstock has grown to become the most widely used scaling platform for the Bitcoin Network. Because Rootstock is fully EVM-compatible, Ethereum developers can build and deploy applications directly on the chain. Assets can be bridged between Ethereum and Rootstock, with Bitcoin (RBTC, pegged 1:1 with BTC) functioning as the native token, allowing for fast and efficient operations, all within the BTC paradigm.

In 2023 Rootstock had its own block explorer which was developed in-house and provided all of the necessary information for their users. When the team reached out to Blockscout, they didn’t want to replace their current explorer (active today at https://explorer.rootstock.io/), but rather augment their explorer capabilities with a full-featured, Ethereum-aligned explorer that included advanced smart contract verification and interaction capabilities.

Up to that point, Blockscout had worked on many EVM configurations, but not one specifically designed for the Bitcoin ecosystem. We were excited for the challenge, and immediately got to work indexing the Rootstock Network and mapping out the required customizations.

Baseline Requirements

Out-of-the-box Blockscout is extremely configurable and provides support for basic operations on any EVM-based chain. Transactions, blocks, accounts, and token features were already accounted for when we started on the Rootstock explorer. Providing realtime updates for transactions and blocks along with accurate revert tx messaging were priority items for the RSK team, and these were also baked into the application. This meant we had a headstart as we catalogued requirements relevant to the RSK environment.

Custom block data

Some of the first changes required simplifying information and removing irrelevant data. For example, Blockscout supports “burnt fees” within an Ethereum context, where a portion of the transaction fee (the base fee) is burned when any transaction is processed. This mechanism was implemented in EIP-1559 and designed to counteract ETH inflation (with mixed results). This concept is not applicable to Bitcoin or RSK, so info removal was an important first step to keep the interface clean and applicable.

Next we needed to augment blocks with additional information. This included adding the minimumGasPrice field to each block. This field is written into the block header by RSK miners to establish the minimum gas price for any transaction included in a block.  The minimumGasPrice can change up to 1% between blocks, so it is something users need to have easy access to so they can price fees accordingly (generally adding an additional 10% in gas fees to act as a buffer).  

We also added additional data fields related to RSK-Bitcoin merged mining. This feature allows Bitcoin miners to mine RSK simultaneously with no additional cost or impact. Information includes the Bitcoin merged mining header, merged mining coinbase transaction (which includes RSKblockinfo), merged mining Merkle proof, merged mining hash, and block difficulty.

RNS support

The RIF Name Service (RNS) enables the use of human readable names for blockchain addresses, helping users to send and receive transactions using personalized domains (ie satoshi.rsk). RNS domains are multichain but primarily utilized on the RSK network. The Rootstock team needed full support for RNS and Blockscout was in the beginning stages of implementing the ENS service for Ethereum chains.

Because we were working on several name service integrations at the same time, we decided to move this development feature to its own dedicated microservice, and leveraged the RNS resolver library to support RNS names specifically. This gave us the opportunity to modularize the feature and provide support for multiple name service integrations, proving to be a valuable feature as we’ve expanded name service support to many chains. The microservice also allows chains to add their own subgraphs for custom name service functionality on their own chains. 

Users can now search for .rsk names on the Blockscout Rootstock explorer and use the name services lookup feature to find and filter info related to .rsk addresses.

Contract verification and interactivity

Blockscout provides a robust contract verification service which streamlines contract verification and interaction. Users can verify a contract directly through Blockscout's UI or use familiar tools like Hardhat or Sourcify. Contracts that have already been verified in other contexts or on other chains are also auto-verified using the Ethereum bytecode database microservice.

Once verified, possibilities for interaction and analysis open up, including reading/writing directly to the contract, opening in Remix, viewing a UML diagram of a contract, testing with a custom ABI, and other useful tools.

When we started on the Rootstock instance in 2023, many of these features were still in development, and a dedicated microservice was launched to provide contract verification services within the RSK environment. This included the ability to identify already deployed contracts, so that contracts sharing the same underlying code were identified when deployed to different addresses.

Contract interaction within the explorer was another requirement for Rootstock. Users needed to be able to read and write to methods in contracts, leveraging the explorer as a secure source of truth for contract interactivity. We refined Blockscout's interactive capabilities to handle these requests, which helped elevate our contract verification services for all of our Blockscout instances.

Branding, identification & speed optimizations

Blockscout provides the ability to easily update colors, logos, and other UI elements to reflect the unique brand identity of any chain. We worked with the Rootstock team to implement their updates including a customized footer and logo enhancements for both light and dark Blockscout modes. This resulted in a clean, Rootstock branded interface that provided all of the UI elements users expect in a full-featured explorer.

We updated the UI with support for Rootstock-specific transactions (REMASC and bridge transactions) for easy identification. Reward Manager Smart Contract (REMASC) transactions are responsible for fairly distributing rewards to participants, and users were interested in quickly identifying these tx types. Additional support for NFTs (the ability to query NFT ownership and NFT image improvement) was also configured for Rootstock users.

Finally, we worked (and continue to work) on increasing performance and indexing speed of the Rootstock explorer. We've made many gains since 2023 through database optimizations to provide a near-real-time explorer for all users.

Ongoing Partnership

When we completed v1 of the Rootstock explorer in early 2024 it was only the beginning of the story. Since then we've completed several major upgrades to the Blockscout architecture and incorporated these seamlessly into the Rootstock instance. This includes features like the Dappscout marketplace for decentralized applications, new charts and stats, an advanced gas tracker, and DeFi interactivity.

We've also supported Rootstock network upgrades and worked closely with the team to implement additional features and troubleshoot issues as they arise. We are working with Rootstock Collective, which consumes Blockscout APIs, to show staked holdings and community membership in the RC dApp. We provide full hosting and maintenance services within our data center, ensuring the Rootstock explorer is always available and supported with optimized resources. This partnership has allowed us to learn more about Bitcoin EVM integrations and improve our customization process for all chains in all ecosystems we support.

The Future of Blockscout and Bitcoin L2s

As we dive into 2025, Bitcoin L2s are one of the fastest growing chain segments launching today. Rollups are thriving in many ecosystems, providing scalability and advancing use cases like games, microtransactions, and efficient trading and borrowing platforms. Bitcoin is the most trusted and secure blockchain, and it makes sense that enhancing programmability and scalability will further elevate the Bitcoin ecosystem, allowing users to tap into huge amounts of liquidity and build DeFi products designed for the masses.

Blockscout is the #1 explorer for Bitcoin-based L2s. Chains like Build on Bitcoin (BOB) and Citrea are leveraging Blockscout to provide a seamless block explorer experience for their users. Thanks to our learnings from Rootstock, Blockscout is well positioned to continue serving the Bitcoin ecosystem in the years to come.

If you are an L2 building on Bitcoin (or any other ecosystem 😉) reach out to learn more about how Blockscout can support your chain and provide your users and developers with a full-featured and streamlined block explorer.