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Build Projects

Guided projects builders complete while progressing through roadmaps — concrete builds with clear ship criteria, not generic todos. Filter by track and difficulty, then open a project for architecture, requirements, and submission notes.

entries // 35 · beginner 10 · intermediate 13 · advanced 12

Category

Difficulty

35 projects in the library

Beginner5 daysbitcoin

BitcoinWallets

Address Format Lab

Generate and validate P2PKH, P2WPKH, P2SH-P2WPKH, and P2TR addresses from the same key material. Explain each encoding.

Skills

Bech32Base58CheckKey derivation basics

Prerequisites

Keys & Addresses · SegWit & Bech32

./view-project

Beginner3 daysbitcoin

BitcoinWallets

BIP-21 Payment URI Tool

Build and parse bitcoin: URIs with amount, label, and message. Generate QR codes merchants can scan.

Skills

BIP-21QR encodingURL query parsing

Prerequisites

Keys & Addresses

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Beginner1 weekbitcoin

Bitcoin

Bitcoin Script Puzzle Kit

Solve and author locking scripts with OP_IF, hash locks, and timelocks. Verify spends on regtest.

Skills

Bitcoin ScriptOpcodesRegtest

Prerequisites

Bitcoin Script · Transactions

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Beginner5 daysbitcoin

Bitcoin

Block Header Inspector

Decode block headers, verify proof-of-work targets, and walk merkle proofs for a chosen transaction.

Skills

HeadersMerkle treesDifficulty bits

Prerequisites

Blocks & Chain

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Beginner4 dayslightning

Lightning

BOLT11 Invoice Decoder

Decode Lightning invoices into amount, payment hash, expiry, route hints, and feature bits. Round-trip encode a test invoice.

Skills

BOLT11Bech32TLV tags

Prerequisites

Invoices · Lightning Overview

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Beginner1 weekbitcoin

BitcoinWallets

Coin Selection Playground

Implement largest-first and branch-and-bound style selection. Visualize waste, change, and fee tradeoffs on a fixed UTXO set.

Skills

UTXOsAlgorithmsFee math

Prerequisites

UTXO Model · Mempool & Fees

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Beginner2 daysbitcoin

BitcoinInfrastructure

Hello Regtest

Spin up bitcoind in regtest, mine your first blocks, fund a wallet, and print a confirmed balance with Core RPC.

Skills

Bitcoin CoreRPCDocker or local install

Prerequisites

Developer Environment

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Beginner1 weeklightning

LightningWallets

LNURL-Withdraw Kiosk

Implement a tiny LNURL-withdraw endpoint that hands out small testnet payments from a pre-funded node.

Skills

LNURLHTTP callbacksInvoice creation

Prerequisites

LNURL · Invoices

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Beginner5 daysbitcoin

BitcoinInfrastructure

Mempool Fee Thermometer

Poll fee estimates and mempool size, then chart next-block vs economy rates so users pick a sensible feerate.

Skills

REST or RPCSimple chartsFee units (sat/vB)

Prerequisites

Mempool & Fees

./view-project

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entries // 35 · beginner 10 · intermediate 13 · advanced 12