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Welcome

jPOS is infrastructure for financial messaging and transaction processing.

If you are here, chances are you need to pack and unpack ISO-8583 messages, connect to remote endpoints, orchestrate transaction flows, and build something that survives contact with production. jPOS can do that, but it helps to approach it as a framework rather than as a small utility library.

What jPOS is​

jPOS is a mature, opinionated Java platform for payment systems. It has been evolving for decades around demanding real-world use cases: gateways, acquirers, issuers, switches, key management, auditability, observability, and high-integrity transaction processing.

That is the good news and the bad news:

  • Good news: the framework already contains a large amount of what serious payment applications need.
  • Bad news: the shortest path is rarely "paste this snippet and move on."

Why this documentation exists​

It is tempting to skip straight to packing and unpacking a message, but most real systems quickly need much more:

  • multiple remote connections with independent configuration
  • inbound and outbound message routing
  • transaction orchestration and failure handling
  • PCI-aware logging and secret management
  • ANS X9.24-related key management
  • HSM integration
  • load balancing and failover
  • PIN translation and EMV support
  • monitoring, alerting, profiling, and operational visibility

jPOS exists to solve this broader class of problems coherently. Ignoring those integrated components often creates more complexity, not less.

info

This site has two jobs:

  • For newcomers: a tutorial path that gets you from setup to working flows.
  • For experienced developers and contributors: a reference for components, patterns, and project structure.

Over time, the goal is to replace the older programmers' guides with documentation that is easier to navigate, easier to update, and closer to the current codebase.

If you are new here, use this order:

  1. Read the project overview to understand the open-source and enterprise pieces.
  2. Continue with the tutorial setup to prepare your environment.
  3. Work through the tutorial sections instead of cherry-picking isolated snippets.

If you already know jPOS well, the docs sidebar and search should get you to the exact area you need.