Learnings from ETHGlobal Prague

ETHGlobal Prague, our first sponsored hackathon of 2025, was a huge success! Of the 217 projects participating, 81 won Blockscout prizes for using the explorer, APIs, or SDK. Of the 10 overall finalists, 7 incorporated Blockscout into their projects. Blockscout was everywhere, and we certainly enjoyed meeting and mentoring all of the up-and-coming developers and app builders in the space.

After the hack we reached out to our winners to learn more about their experience, how they incorporated Blockscout, what worked (and what didn’t), and what they’ll be working on next. 

Below are responses from GM (🏆 Best Use of Blockscout), TruDelnik (🏆 Best Merits Use Case ) and KarmaProof (🏆 Best SDK Integration) along with some overall graphic insights from Blockscout pool prize entrants who filled out our short survey.

Tell us about your project in a few sentences

• GM is a terminal based ethereum wallet currently with apple keychain support for storing private keys.
• TruDelník is a multi-chain, risk-based Web3 game where players stake crypto, climb an exponentially growing multiplier ladder, and can cash out at any time—or lose it all on the next step.
• KarmaProof brings real-world good deeds on-chain by turning charitable actions like blood donations, volunteering, and environmental cleanup into verifiable blockchain credentials.

What made Blockscout the right choice for your project?

• Blockscout provides free APIs (up to a limit) without an API key. Almost every other provider requires an API key. Since my wallet is open source, I would have to ask the users to create an account with these data providers to get an API key for free. This creates an extremely bad UX for open-source applications. But only blockscout makes it practical. 
• Blockscout gave us two things we couldn’t find together anywhere else:
  • Merits module for effortless, on-chain reputation that became our progression system.
  • True multi-chain coverage (including Flare & Berachain)
• Blockscout's comprehensive SDK, Merits integration, and multi-chain support made it perfect for our social impact platform. Unlike other explorers, Blockscout offers seamless transaction notifications, built-in rewards through Merits, and excellent blockchain support for many networks.

What specific Blockscout features or APIs were most valuable for your project?

• I extremely like the feature that it doesn't require an API key for limited usage. I used the transactions API, which is common from other providers, not much technical difference
• Merits API – 1 Merit per game; higher difficulties unlock at Merit thresholds and verified-contract metadata – lets players audit our Game.sol logic directly from the explorer.
• The v2 API for real-time transaction monitoring and the Merits authentication flow using SIWE were very useful. These allowed us to create a seamless UX where users can track their proof verifications and exchange Karma tokens for Merits.

How did Blockscout help you achieve your hackathon goals?

• I was able to display some recent transactions in the address book. My application makes very few API calls and blockscout is the only service that doesn't require an API key.
• The team was always available and quickly unblocked us, so we could ship on time.
• Blockscout enabled us to build a complete transaction tracking system and rewards 'bridge' in just one weekend. The Merits integration gave us an instant way to provide Web3 rewards for real-world good deeds, perfectly aligning with our mission.

Any improvements to Blockscout that would help you?

• Light client friendly data. Currently blockscout is only giving data, but giving merkle proofs would be a crazy game changer and help wallets to also verify data from the centralised server against stateroot (which can be separately verified from consensus light clients).
• A Hackathon Toolkit bundle—pre-made starter repos, mock networks, and UI widgets for Merits—would shorten the runway for future teams.
• Quicker metadata availability for NFTs that were just minted or an automatic fallback to reading on-chain, since we had some issue with the metadata not being available yet if the NFT was just minted.

What would you tell other builders considering using Blockscout for their projects?

• Use it bro, it's actually better than every data provider!
• Start early; the docs are clear and the support is lightning-fast.
• Don't just use Blockscout as an explorer - leverage the full SDK and Merits system to create engaging user experiences. The transaction notifications and one-click explorer access significantly improve dApp usability.

Do you plan to continue working on your hackathon project, what new features can you imagine?

• Yes I am planning to add Reown (WalletConnect) support in the short term. Eventually I want to verify the data from using lightclients.
• Yes—next steps are mainnet launch, NFT badges, and more chains.
• Yes, we plan to expand supported charitable organizations and add more proof types beyond donations and email verification. We also plan to expand on the rewards store adding more options to redeem Karma tokens.

A Big Blockscout Thank you to GM, TruDelnik and KarmaProof for their thoughtful responses. Check out their projects below.

• GM Live demo and source code
• TruDelník Live demo and source code
• KarmaProof Live demo and source code

We'd also like to thank all projects who participated and filled out the Blockscout survey.  We look forward to building with you at the next hackathon!

We welcome your feedback on topics you'd like to see covered or any questions you have. Visit us on X or Discord to get your explorer questions answered or get your project added to our growing network list.