About
Go under the hood of the XRP Ledger. Build `xrpld` from source and learn how the node works from the inside: architecture, storage, cryptography, networking, RPC, consensus, and then extend the protocol.
Go under the hood of the XRP Ledger
This is the deep track for developers who want to understand xrpld, the C++ node that runs the XRP Ledger, from the inside, and then change it.
Who it's for. You are comfortable with C++, the command line, and git. You do not need to be a blockchain expert; the ledger-specific parts are explained as you go. It is an advanced, hands-on journey of about 50 hours.
What you'll be able to do by the end. Build and run your own node from source, read the codebase with confidence, add a custom RPC handler, explain how consensus keeps every node in agreement, follow the amendment process that evolves the protocol, and, in the capstone, ship a small protocol extension of your own.
How it works. Start with the short Welcome module, then take the phases in order; each builds on the last:
- Run a node: compile
xrpldand run it locally. - Inside rippled: architecture, codebase, storage, and transaction processing.
- Cryptography: keys, hashing, signing, and the pitfalls.
- Networking: how nodes find each other and talk.
- Communication (RPC): build and test your own command.
- Consensus and Extend the protocol: how the network agrees and how amendments evolve it.
- Capstone: extend the protocol end to end.
Every module ends with a summary and a short auto-graded quiz; many add a self-checked micro-lab or a mentor-reviewed homework. The code is verified against the stable rippled 3.2.0 release, and each module links to the exact directory or file in the source where its subject lives.
Modules
Start here
Run a node
Build & run your own xrpld node
LockedComplete Welcome to the Core Dev Bootcamp to unlock this module.
Turn the open-source rippled code into a running node: set up the C++ toolchain, compile the `xrpld` binary with Conan + CMake, then run it locally in standalone mode.
Inside rippled
Phase overview: Inside rippled
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Inside rippled phase: architecture and tooling, state and storage, and transaction processing, and how the sixteen modules fit together.
The Application layer
LockedComplete Phase overview: Inside rippled to unlock this module.
How the `Application` class wires rippled together — the central orchestrator that owns and coordinates every subsystem, plus the job queue and configuration.
Navigating the rippled codebase
LockedComplete The Application layer to unlock this module.
Find your way around the modern rippled source tree (`include/xrpl`, `src/libxrpl`, `src/xrpld`) and the naming conventions used throughout.
The complete transaction lifecycle
LockedComplete Navigating the rippled codebase to unlock this module.
Follow a transaction from creation and signing through submission, validation, consensus, canonical application and final validation.
Development & debugging techniques
LockedComplete The complete transaction lifecycle to unlock this module.
The tools and workflows for investigating rippled behaviour — standalone mode, logging, gdb, and inspecting ledgers and transactions.
Protocols & wire messages
LockedComplete Development & debugging techniques to unlock this module.
How rippled nodes talk on the wire — the peer protocol, protobuf message types, and where message handling lives.
State-management foundations
LockedComplete Protocols & wire messages to unlock this module.
Why blockchain state needs a cryptographic commitment, and the tree / Merkle / Patricia-trie foundations behind XRPL's SHAMap.
SHAMap architecture & hashing
LockedComplete State-management foundations to unlock this module.
The structure of XRPL's SHAMap — inner vs leaf nodes, node types, key-based navigation, and how hashes roll up to the root.
SHAMap synchronization & proofs
LockedComplete SHAMap architecture & hashing to unlock this module.
How nodes compare and sync SHAMaps by hash, and how compact Merkle proofs let clients verify state without the full ledger.
NodeStore architecture
LockedComplete SHAMap synchronization & proofs to unlock this module.
The pluggable, hash-indexed key-value store that persists SHAMap nodes, and its `NodeObjectType` model.
Storage backends & database operations
LockedComplete NodeStore architecture to unlock this module.
The NodeStore backends (NuDB, RocksDB…) and the fetch / store / batch / async lifecycle above them.
Caching & resource management
LockedComplete Storage backends & database operations to unlock this module.
The cache layer that keeps hot nodes in memory, and the memory / disk / throughput characteristics of a production node.
Transactor architecture
LockedComplete Caching & resource management to unlock this module.
The `Transactor` base class and framework — contexts, phases, and how every transaction type extends a shared base.
The transaction processing pipeline
LockedComplete Transactor architecture to unlock this module.
The four-phase validation pipeline (preflight → preclaim → doApply → finalization) and what each phase may and may not do.
State modification, fees & sequences
LockedComplete The transaction processing pipeline to unlock this module.
How a transactor modifies ledger state through views, and how fees, reserves and sequence numbers are handled.
TER result codes
LockedComplete State modification, fees & sequences to unlock this module.
The Transaction Engine Result taxonomy — tes / tec / ter / tef / tem / tel — and how to choose the right code.
Case study — the CheckCreate transactor
LockedComplete TER result codes to unlock this module.
A code-level walkthrough of a real transactor (`CheckCreate`) across preflight, preclaim and doApply.
Cryptography
Phase overview: Cryptography
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Cryptography phase: primitives, keys and encoding, and the applied crypto of signing and the peer handshake, across eight modules.
Security foundations
LockedComplete Phase overview: Cryptography to unlock this module.
The four pillars of blockchain security and the lifecycle of a cryptographic key in XRPL.
Hash functions in XRPL
LockedComplete Security foundations to unlock this module.
SHA-512Half, hash prefixes and ledger namespaces, and how hashing underpins IDs, keys and integrity.
Key generation & derivation
LockedComplete Hash functions in XRPL to unlock this module.
How rippled turns randomness (or a seed) into secp256k1 / ed25519 key pairs and account IDs.
Secure memory handling
LockedComplete Key generation & derivation to unlock this module.
Why secrets must be wiped from memory and how rippled does it (`secure_erase` / `OPENSSL_cleanse`).
Base58Check encoding
LockedComplete Secure memory handling to unlock this module.
How XRPL encodes account IDs, keys and seeds as human-readable strings with a checksum and type byte.
Transaction signing & verification
LockedComplete Base58Check encoding to unlock this module.
The signing / verification pipeline for secp256k1 and ed25519, canonical signatures and malleability.
The peer handshake
LockedComplete Transaction signing & verification to unlock this module.
How two nodes prove identity and bind a session cryptographically during the peer handshake.
Crypto pitfalls & performance
LockedComplete The peer handshake to unlock this module.
Common cryptographic mistakes to avoid and the performance characteristics of XRPL's cryptography.
Networking
Phase overview: Networking
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Networking phase: the overlay network, peer discovery, and message relaying, in three modules.
The overlay network
LockedComplete Phase overview: Networking to unlock this module.
rippled's peer-to-peer overlay — mesh topology, connection types and the OverlayImpl / PeerImp architecture.
Peer discovery & connection lifecycle
LockedComplete The overlay network to unlock this module.
How nodes find peers (config, DNS, gossip, crawler) and the lifecycle of a peer connection.
Handshake & message relaying
LockedComplete Peer discovery & connection lifecycle to unlock this module.
The protocol handshake and how messages (proposals, validations, transactions) are relayed and squelched — plus a look at proposed protocol extensions.
Communication (RPC)
Phase overview: Communication (RPC)
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Communication (RPC) phase: how the outside world talks to a node, and how to build, harden, and test your own command, in six modules.
RPC architecture & request flow
LockedComplete Phase overview: Communication (RPC) to unlock this module.
How rippled's RPC layer dispatches JSON-RPC / WebSocket / gRPC requests to handlers.
RPC authentication & error handling
LockedComplete RPC architecture & request flow to unlock this module.
Role-based access control and the RPC error-code system.
Building a custom RPC handler
LockedComplete RPC authentication & error handling to unlock this module.
Implement a new RPC command end-to-end — the handler function, registration and conditions.
RPC handler best practices
LockedComplete Building a custom RPC handler to unlock this module.
Patterns and helpers for robust, consistent RPC handlers.
Testing RPC handlers
LockedComplete RPC handler best practices to unlock this module.
How to test RPC handlers with the jtx framework and debug them.
Advanced RPC features
LockedComplete Testing RPC handlers to unlock this module.
Subscriptions, WebSocket streams and gRPC — beyond simple request / response.
Consensus
Phase overview: Consensus
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Consensus phase: the ledger being agreed on, the agreement algorithm itself, staying in sync, and the trust layer, in seven modules.
Ledger architecture & data structures
LockedComplete Phase overview: Consensus to unlock this module.
The `Ledger` object and its data structures — LedgerHeader and the state and transaction trees.
Consensus fundamentals
LockedComplete Ledger architecture & data structures to unlock this module.
The XRP Ledger Consensus Protocol — what it agrees on and the generic consensus engine.
Consensus lifecycle & phases
LockedComplete Consensus fundamentals to unlock this module.
A consensus round in detail — modes, phases (open / establish / accepted) and timing.
Ledger acquisition & the tx lifecycle
LockedComplete Consensus lifecycle & phases to unlock this module.
How a node acquires and validates ledgers, and the end-to-end path of a transaction across RPC, peers and consensus.
Consensus validations
LockedComplete Ledger acquisition & the tx lifecycle to unlock this module.
How validators sign ledgers, how validations are collected, and how a ledger becomes fully validated.
Consensus peers & the UNL
LockedComplete Consensus validations to unlock this module.
Trusted validators, the UNL and negative UNL, and how peers participate in consensus.
Transaction ordering
LockedComplete Consensus peers & the UNL to unlock this module.
How the network agrees on a deterministic, salted canonical order for transactions in a ledger.
Extend the protocol
Phase overview: Extend the protocol
LockedComplete Build & run your own xrpld node to unlock this module.
Your map of the Extend the protocol phase: the AMM as a worked example of a big extension, then the amendment system that activates protocol changes, in six modules.
AMM architecture & logic
LockedComplete Phase overview: Extend the protocol to unlock this module.
The Automated Market Maker — pool / pseudo-account design, LP tokens, and the constant-product maths.
AMM transactions & pathfinding
LockedComplete AMM architecture & logic to unlock this module.
The seven AMM transaction types and how AMM liquidity is integrated into pathfinding alongside the order book.
Amendments — overview & architecture
LockedComplete AMM transactions & pathfinding to unlock this module.
How protocol upgrades work on XRPL — the amendment system, feature flags and the AmendmentTable.
The amendment lifecycle
LockedComplete Amendments — overview & architecture to unlock this module.
The path of an amendment from introduction through majority to activation.
Voting & network coordination
LockedComplete The amendment lifecycle to unlock this module.
How validators vote on amendments and how the network coordinates activation.
Amendment impact & monitoring
LockedComplete Voting & network coordination to unlock this module.
How an amendment changes transaction processing and the ledger, and how to monitor amendment status.
Capstone
Capstone: extend the protocol end to end Capstone
LockedComplete Case study — the CheckCreate transactor and Crypto pitfalls & performance and Handshake & message relaying and Advanced RPC features and Transaction ordering and Amendment impact & monitoring to unlock this module.
The integrative project: design and build a small protocol feature, a new transaction type gated behind an amendment, with an RPC command and tests, on rippled 3.2.0.
Achievements
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Say hello to the cohort or complete a module to earn your first milestone.
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