Crypto Gloss

David Schwartz

David Schwartz (online pseudonym: JoelKatz) is the Chief Technology Officer of Ripple and one of the three original co-architects of the XRP Ledger (XRPL) alongside Jed McCaleb and Arthur Britto, having designed core components of the Ripple Protocol Consensus Algorithm (RPCA) — a consensus mechanism in which a quorum of trusted validator nodes (selected via Unique Node Lists, or UNLs) must agree by 80% supermajority on the validity of a transaction set before ledger closure — achieving transaction finality in 3–5 seconds with zero mining and negligible energy use compared to proof-of-work systems.

Background

David Schwartz studied computer science at the University of Houston. In the 1990s, he founded a company building distributed encrypted cloud storage systems — conceptually ahead of its time — that encountered commercial difficulties. He subsequently worked in software development and security. By 2011, he had encountered Bitcoin and within months began work on what would become the XRP Ledger alongside Jed McCaleb and Arthur Britto.

Schwartz uses the online handle “JoelKatz” — derived from his admiration for Joel Spolsky and Katz (the creator of the vi text editor) — which predates his Ripple work and remains his primary public identity online.

XRP Ledger Design

Schwartz and co-designers created the XRPL with specific design goals different from Bitcoin:

  • No mining — Eliminates energy waste; validators are identified entities, not anonymous PoW miners.
  • Fast settlement — 3–5 second ledger closure, 1,500 TPS baseline (expandable).
  • Low cost — Micro-XRP transaction fees (destroyed, not paid to validators).
  • Trust-based validator model — Each user selects a Unique Node List (UNL) of validators they trust; consensus forms when 80% UNL agreement is reached.

RPCA (Ripple Protocol Consensus Algorithm):

Unlike Nakamoto consensus (longest chain wins), RPCA achieves finality through validator agreement. If validators are chosen without sufficient UNL overlap between different users, ledger forks are theoretically possible. Schwartz has written extensively on XRP’s fork safety properties and how UNL diversity affects safety/liveness tradeoffs.

Role at Ripple

Schwartz joined Ripple (then OpenCoin) as a founding engineer and CTO. He was compensated in XRP. His role has included:

  • Protocol architecture and RPCA design.
  • Smart contract language (Hooks) and XRPL amendment governance.
  • Public spokesperson and technical educator for Ripple and XRP.
  • Architecture of Ripple’s payment network products (ODL, xRapid, xVia).

He has served as Ripple’s CTO continuously since founding. His Twitter account (@JoelKatz) is one of the most-followed and most-informative accounts for XRP and Ripple technical discussions.

SEC vs. Ripple

The SEC sued Ripple in December 2020 alleging XRP is an unregistered security. Schwartz was a key technical advisor to Ripple’s legal defense. In July 2023, Judge Analisa Torres issued a partial summary judgment finding XRP was not a security when sold on exchanges (programmatic sales), while institutional direct sales may have been unregistered securities. Schwartz publicly characterized the ruling as a significant vindication. The case saw further proceedings through 2024.

Key Dates

  • 2011 — Co-designs XRP Ledger with Jed McCaleb and Arthur Britto.
  • 2012 — Ripple (OpenCoin) formally founded; Schwartz joins as CTO.
  • 2013 — XRPL mainnet live; XRP Ledger transaction processing operational.
  • December 2020 — SEC sues Ripple; XRP delisted from Coinbase and other U.S. exchanges.
  • July 2023 — Partial summary judgment favorable to Ripple on programmatic XRP sales.
  • 2024 — Further SEC vs. Ripple proceedings; settlement discussions.

Common Misconceptions

  • “The XRP Ledger is centralized because Ripple controls validators.” — The XRPL has 35+ independent validators, many operated by universities, companies, and exchanges. Ripple runs some validators but not a majority; UNL diversity is a key design property.
  • “David Schwartz is the same as Jed McCaleb.” — Jed McCaleb and David Schwartz both co-designed XRP, but McCaleb left Ripple in 2013 to co-found Stellar. Schwartz has remained Ripple’s CTO throughout.

Last updated: 2026-04

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