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The Payments Engineer Playbook

news.alvaroduran.com

The only publication on Earth tailor-made for the builders of money software. Click to read The Payments Engineer Playbook, by Alvaro Duran, a Substack publication with thousands of subscribers.

DatabasesDistributed systems / cloudCrypto / fintech

’23’24’25’26
Posts
164 from 31 May 2023 to 21 Oct 2026
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weekly (48 in the last year)
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personal blog
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2026 41

  1. Why Money Software Must Have No Dependencies
  2. How to Apply Secure By Design Practices To Money Software
  3. How To Choose a Database For Your Ledger
  4. Datomic, or When The Past Is The Product
  5. YugabyteDB and the Responsibility of Global Transactions
  6. FoundationDB And The Case For Extreme Ledgers
  7. XTDB, Time traveling, and the ‘As Of’ Ledgers
  8. Spanner Lets You Top Up on Earth and Pay for Groceries on Mars
  9. Multi-currency ledgers for single-currency businesses
  10. Why Optimistic Locking in Ledgers Isn’t Always a Good Idea
  11. Assume that Manual Work in a Ledger Is Impossible
  12. The Playbook's 2026 Beach Reads
  13. Forget Agents: Here's What's Great About x402
  14. Why You Can Have Too Much Idempotency In Ledgers
  15. Losing The Fear of SQL
  16. A Ledger is 3 Products in 1
  17. Don't Be Careful, Be Competent
  18. The Missing State In Your State Machine
  19. How to Recover The Flexibility of Paper In Ledgers
  20. In An Agentic Commerce World, Fraud Will Be Indistinguishable From Legit
  21. Virtual Bank Accounts Are Virtually Inexhaustible
  22. No Such Thing As A Currency Of Reference
  23. Source-Destination Pairs Need Imaginary Accounts to Work
  24. Why Database-Layer Double-Entry Is a Bet, Not a Guarantee
  25. The Only Accounting You Need to Know to Build a Ledger
  26. There Are Only 3 Databases You Can Trust With Your Money
  27. Nobody Got Fired for Uber's $8 Million Ledger Mistake?
  28. Ledger Transactions Don't Have to Be Atomic
  29. The Luxury Playbook for Online Businesses
  30. Why Ledgers Are More Than Data Warehouses of Money
  31. You Don't Know What a Ledger Is For
  32. How to Explain Accounting To Payments Engineers
  33. Why Ledgers Must be Immutable
  34. Accounting For Multi-Currency Ledgers
  35. Modern Treasury's Stablecoin Sandwich
  36. Stablecoins for Skeptics
  37. Ledgers of Catan
  38. Why Low Cardinality Accounts Are A Ledger's Bottleneck
  39. TigerBeetle's Stablecoin Mistake
  40. Why Don't You Use Generics in Ledgers?
  41. Money as Metadata

2025 51

  1. The Playbook's 2025 Year In Review
  2. From Stock Markets To Ledgers, Part VI: Mechanical Sympathy
  3. From Stock Markets To Ledgers, Part V: Continuous Deployment
  4. From Stock Markets To Ledgers, Part IV: Queues
  5. From Stock Markets To Ledgers, Part III: Time
  6. Raft Consensus in 2,000 words
  7. From Stock Markets to Ledgers, Part II: Fault-tolerance
  8. From Stock Markets To Ledgers, Part I: Fairness
  9. What payment providers can learn from Go contexts
  10. Why AI Commerce Isn't Going Anywhere
  11. How To Prevent Cache Stampedes
  12. What Makes DynamoDB a Good Database Choice for Payments
  13. CQRS Is Just Balances And Records
  14. How To Review Code That Deals With Money
  15. How to Build Payment Webhooks Fast
  16. The Sequence-Speed tradeoff
  17. Richard Pryor Stole a lot of Half Cents and Bought a Ferrari
  18. Paying At The Pump: Why Auth and Preauth Are Not The Same Thing
  19. The Playbook's 2025 Beach Reads
  20. Testable Payment Webhooks
  21. Pull Requests Are Herbie
  22. Code-First Reliability: 4 Unconventional Approaches to Always-on Payments
  23. Database Migration Wartime Stories
  24. The Joy of Being On Call For Payment Systems
  25. The Ultimate Guide to Payment Tokens
  26. Why Payments Are Path-Dependent
  27. Code-First Reliability in Payment Systems
  28. Why Payments Aren't Money Movements
  29. Ouch! What To Do When A Payment Fails
  30. Stripe Deploys 1,000 Times A Day And You Don't Deploy On Fridays
  31. Enterprises Hope That Python Will Make Them AI-first
  32. The Technical Face of Payments as a Service
  33. The Regulatory Face of Payments as a Service
  34. 3RI Is A Technical Lever
  35. This newsletter will get you promoted at a fintech company
  36. 5 Common Antipatterns in Payment Systems Design
  37. Never Make a Status Request Again: How to Communicate with PSPs
  38. Payment State Machines Are Not Cyclical
  39. Leveraging Spaced Repetition to Power My Weekly Newsletter
  40. The Unreasonable Effectiveness of Logistic Regression for Busting Payments Fraud
  41. The Best Payments Database Is the One You Aren't Using
  42. Caching In the Past Is a Rare Event
  43. 3 Ways You Can Improve Your Payments Authorization Rate Right Now
  44. Why Orchestration Matters To Payments Engineers
  45. Hard-won Insights as a Service: The value of Payments Orchestration
  46. If Amazon Can't Figure Out How To Make Money From Blockchain Databases, Nobody Can
  47. Meta's Card Catastrophe: Payments as Corporate Benefits
  48. Banks move money by sharing files, and that's OK
  49. A Tale of Two Ledgers
  50. The Intuition of Money
  51. Payments Patterns: Elements of Reusable Money Software

2024 46

  1. NoDB: Processing Payments Without a Database
  2. The Playbook's 2024 Year In Review
  3. Consistency, Availability, Prowess: How Stripe and Shopify push the limits of distributed payments
  4. How to build 99.999% uptime payment systems
  5. How Modern Treasury Invented Event Locking
  6. Payment for Payment Flow: How revenue sharing agreements impact payment orchestration
  7. Payment Cards Are An Insecure Protocol
  8. Dynamic Linking, and the limitations of 2FA in Payments
  9. Exemptions and Data Science: The European Way of Building 3DS
  10. The Customer Must Never Know: The American Way of Building 3DS
  11. How to design mixed payment methods with store credits
  12. The Payments Engineer Playbook Is Going Paid in 2025—Here's What You Need to Know
  13. Why Payments Engineers Should Avoid State Machines
  14. An Approach To Ledgers That Makes Multi-Currency Not Just Possible, But Easy
  15. Engineers Do Not Get To Make Startup Mistakes When They Build Ledgers
  16. The Most Important Book In Payments Is a Data Systems Book
  17. Boring Is Good: How Shopify Prepares for Black Friday
  18. How To Scale Payment Systems With The Saga Pattern
  19. Exactly-Once Payments At Airbnb
  20. Cringey, But True: How Uber Tests Payments In Production
  21. Stripe Made The Obvious Choice When Building Its Payments API. It Took Two Years To Fix It.
  22. Doubling Down On The Engineers of Payments
  23. We Love Writing Software So Much, We’re Willing To Do It For Free
  24. Enterprise Python
  25. Not Now, Honey! I'm Trying to Compile This Code
  26. The Prototype's Language
  27. Keeping Up With The Databases
  28. The Narrow Waist of Payments Orchestration
  29. The Economics of Open Source Payments
  30. A Sketch of a Payment Systems Protocol
  31. A Problem-First Approach To Building Engineering Teams
  32. What Amazon Can Teach Payments Companies About Collaboration
  33. Acquiring: Call It a Prototype
  34. Scale is Overrated in Payments. You Should Focus on Scalability Instead.
  35. Pyments: How to Design Payment Applications in Python
  36. Bad API design costs a lot of money. In payments, it's clear why.
  37. A Taxonomy of Payment Methods
  38. Advice I Wish I Had Known When I Built My First Payment Application
  39. The Uncontrollability of Payment Systems
  40. Nobody Gets Fired For Choosing Java
  41. Relational Databases Aren't Paying Off In Payments
  42. Pizza Place Payments
  43. Fighting Ghosts With Gremlins: A Primer on Credit Card Exemptions
  44. Check Me If You Can
  45. Tokenization, or How I Learned to Stop Worrying and Love the Vault
  46. Gumroad Wallet, A $100M Opportunity

2023 26

  1. Building Money In Transit
  2. Sailing Ships In The Polar B2B Waters
  3. The Payment Experience Manifesto
  4. Launching The Databases of Money
  5. Announcing The Databases of Money
  6. Must There Be A Payment Platform?
  7. The Suits Gap
  8. Mario Andretti's Law
  9. Designing Payment Applications
  10. The Turbulent Tango Of Payment Providers
  11. What Makes Payment Applications Different?
  12. How To Communicate With Software Engineers So That They Understand You
  13. The John Scully's Disease
  14. State Machines Are Probably a Bad Idea
  15. The Relevance Of Tech Conferences In A Post Pandemic World
  16. Transformational, Not Transactional
  17. The Concurrency Ambition
  18. Payment of the Seas
  19. A Grid in the Sky, part III - Hackers and Pilots
  20. A Grid in the Sky, part II - Bonus points
  21. A Grid in the Sky, Part I: The Apple of European travel
  22. Where Does Your Credit Card Data Go When You Press Pay?
  23. Abstracting Money Wisely
  24. NDC: Nothing Decent Coming
  25. Why OTAs should not integrate with Stripe?
  26. Coming soon