[Top Builder 2025]: Blockstamp.app

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🏗️ Top Builder 2025 Application Form to track progress through Round 1 - 3 ~ Currently in Round 1

📝 Instructions

Welcome to the Top Builder competition! Before you begin, here’s what you need to know:

1. Eligibility: Only teams that have been officially selected for Top Builder by PlebLab are eligible to use this form.
2. Detailed Submissions: Provide comprehensive information to assist the judges in evaluating your project effectively.
3. Submission Deadlines: Adhere to submission deadlines for each round to remain in good standing.

🧑‍🤝‍🧑 The Team

• Team Name: Blockstamp
• Number of Founders: 1
• Team Background: I'm a Bitcoin enthusiast looking to learn more about building software on top of Bitcoin. Professionally I'm a mechanical engineer. I started building Blockstamp as a learning exercise for myself and looking to continue the journey.
• Bitcoin & Lightning Involvement: I've contributed to a few hackathons through ATLbitlab and helped with some improvements to the ATLbit.dev website. Blockstamp.app is the first solo project that I have deployed.
• Origin Story: I had a niche problem - I wanted to know the blockheight at a specific date (my nephew's birthday, so I could have it engraved on a gift for my brother). I found no readily available tools that accomplished this in an automated way, so I started writing a script that made RPC calls to my Bitcoin node. Using a binary search algorithm, I got the script working reliably and returning accurate blockheights. Eventually I wrote a frontend with the help of some fellow ATLbitlab attendees and deployed it to blockstamp.app. In the end, I accomplished my primary goal - learning - and I had a simple but useful and functioning application.

💡 The Idea

• Project Overview: Blockstamp.app upgrade -> allow users to "stamp the blockchain" to commemorate meaningful events (birth of a kid, wedding dates, etc.). With the upgrade, users will be able to schedule a Bitcoin transaction at a date of their choosing which contains their message in an OP_RETURN transaction. The site will charge the user a lightning fee to cover the future transaction fee plus a small additional fee for providing the service.
• Website: https://blockstamp.app/
• GitHub: https://github.com/gratten/blockstamp
• Project Stage: The site currently returns the blockheight for any arbitrary date provided by the user. The upgrade will enable the "blockchain stamping" functionality outlined above.
• Supplementary Materials:
• • Presentation I gave at ATLbitlab on the project - https://docs.google.com/presentation/d/1T5EYdXaESDjARv0KMgHxwlQzshtZaCWaX3pxLPMfFY4/edit?usp=drive_link

📚 Additional Information

• Additional Links/Info:
  TODO
• • develop logic to request user message if a future date is submitted
• • integrate a database to store target dates/blockheights and user messages
• • develop blockheight estimation logic (and potentially re-estimation logic that runs at a regular time interval)
• • develop fee estimation logic
• • integrate lightning payment
• • stretch goal - simplified mempool.space style UX that allows users to see their "stamps" on the blockchain in an aesthetic way

📌 Submission Type

• Initial Project Creation

🚀 Current Project Progress

• Progress Made: So far, I've developed a proof of concept cli tool that prompts the user for a desired future blockheight and message. The tool then waits for the target blockheight, then builds, signs and sends a transaction containing the message in an OP_RETURN. This tool was developed using regtest.
• Challenges Faced:
• • Estimate fees: It may be difficult to estimate future fees, particular if the transaction is in the far-future. A solution to mitigate this challenge could be to limit how far out a user is allowed to schedule a transaction.
• • Estimate blockheights accurately: If a user is interested in the transaction taking place at a specific time, the initial blockheight estimate may become inaccurate. A potential solution is to create an automated function that re-estimates target dates/blockheights on a regular basis (hourly, daily, etc.)
• Future Roadmap of what's next: Would be really cool to tie this application to an Etsy style webstore where you can buy items engraved with your blockheight and "stamped" message!

⏳ Round 1 Milestone

• Keep in mind that completion will need to be by February 8th, 2025.
• First-round milestone the team has set for themselves:
• The site is successfully:
• • estimating future blockheight per user entered target date
• • prompting user for the text they'd like to include in the OP_RETURN
• • storing the estimated target blockheight and the user entered text in a database
• • building a transaction including the user submitted text in an OP_RETURN and the target blockheight in an nLockTime
• • signing and broadcasting the transaction

📝 Submission Complete

• All required information has been provided above.

📅 Top Builder Program Structure

Registration Opens: Monday, October 28th, 2024

• Application: Interested teams apply for Top Builder.
• Selection: Teams will be chosen based on their application. See FAQ for details.

Round 1: January 6th - February 8th, 2025

• Workshops: PlebLab weekly workshops start, available live and online.
• Chat Access: Selected teams join the PlebLab internal chat.
• Mentorship: Begins for teams.
• Project Milestones: Teams are set and judged on their first-round milestones.

Round 2: February 9 - 22nd, 2025

• Team Reduction: PlebLab cuts half of the Top Builder teams. (Only half continued in Round 2.)
• Project Milestones: Teams are set and judged on their second-round milestones.
• Workshops: PlebLab weekly workshops continue.
• Mentorship: Continues.

Round 3: Starting February 23rd, 2025

• Team Reduction: PlebLab narrows down to 5 Top Builder teams. (All will be pitching in Austin.)
• Final Milestones: Teams set final project milestones for the last round.
• Preparation: Teams prepare their pitch in front of judges. Final teams are contacted to come to Austin for Startup Day.

Final Round at Startup Day: March 13, 2025

• Preparation: Teams work on their final pitches at PlebLab.
• Presentations: Final teams present before judges on Startup Day.
• Deliberation: Judges decide during a happy hour.
• Announcement: The winner of Top Builder is announced at Austin BitDevs.
• Celebration: After-party for Top Builder.

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Update - 1/30/25

• added logic to distinguish when a user enters a past date or future date and behave accordingly
  • if past date, app works as normal (binary search on blockchain to return corresponding blockheight)
  • if future date, app estimates a target blockheight and presents the user with a text input field
• implemented a database to store the target date, target blockheight, and "stamp" aka user-entered text to be included in the OP_RETURN upon submission of the "stamp" input field
• added /stamps page to display target blockheight, user-submitted "stamps", and transaction ID after broadcast
• implemented building, signing and broadcasting of a bitcoin transaction containing the "stamp" in an OP_RETURN
• implemented a function to monitor target blockheights in the database and compare to the the current blockheight - when a match is found the transaction is broadcasted and /stamps page is updated with the transaction ID
• added logic to check if a transaction has been mined yet, if so indicated with green text on the /stamps page
• began testing with testnet today, successfully broadcasted a few transactions to the network that were eventually mined/confirmed
  • https://mempool.space/testnet/tx/3d4d2d495b7a205817bbd362f8ac3d32d104bd320bc0fdcd5faa6f9e78e93503
  • https://mempool.space/testnet/tx/390c5f07bee6efb09d32cd1a4ecd6cd53999d9ba58061ac79cffd9aed6c41b81
• following data on the site is dynamically rendered via HTMX, polling the server every 3 seconds:
  • current blockheight and date the block was mined
  • blockheight or blockheight estimate corresponding to user-submitted date
  • stamp submission text field
  • data in table on /stamps page, including transaction ID after broadcast and green text after transaction is mined

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See link below for my demo:

https://vimeo.com/1054653652?share=copy#t=0

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Update 2/10/25:

• started working on implementing lightning payments
• I've already got an instance of lnbits running, so plan is to use the lnbits api to serve invoices and maintain a database of lightning transactions
• so far, I have it serving an invoice for a static fee, including QR code and invoice string
• stamps will not be added to the database without a successful lightning payment

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Update 2/17/25

• implemented lightning payments using lnbits API
• got it working by setting up polling from the app to the lnbits instance, would like to eventually get it working using webhooks
• all the critical pieces are in place and working, but I'm starting to re-think my deployment strategy
• currently using the lnbits instance running on my VPS
• starting to explore using docker to simulate the VPS environment locally, so I can test with testnet locally and mainnet once deployed

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Here's my latest demo:

https://vimeo.com/manage/videos/1059009551