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The PATH specification — pillars, transverse layers, and the conventions every implementation follows.
This section specifies the protocol. If you are new to PATH, Learn explains the ideas first; this section assumes them.
Quickstart
A working integration in about fifteen minutes.
Open →Versioning
Two version lines, and which one to pin.
Open →The pillars
PATH ID
Subjects, verified identifiers, attestations.
Open →PATH ADDRESS
Opaque addresses, receive targets, standing intent.
Open →PATH REQUEST
Payment requests and checkout sessions.
Open →PATH CONNECT
Bounded, revocable authorisation.
Open →PATH SETTLEMENT
Signed receipts and reconciliation.
Open →Transverse
PATH FINDER
Reachability: SONAR then RESOLVER.
Open →PATH INTEROP
One URI across QR, deeplink and in-app.
Open →Discovery
What an operator publishes about itself.
Open →Working with it
Errors
The error registry and what to do with each code.
Open →Conformance
Declaring profiles, and how a third party checks.
Open →Security
Threat model, and the mistakes that matter.
Open →Conventions used throughout
Requirement levels. MUST, SHOULD and MAY carry their RFC 2119 meanings. A SHOULD that you do not follow is a decision to document, not a detail.
Status labels. Every section carries one:
Times are RFC 3339 in UTC. Amounts are decimal strings, never floats — a binary float cannot
represent 0.1, and a payment system that rounds is a payment system that loses money in a
direction someone will eventually notice.
Identifiers in examples are fictional.
Two rules that explain most of the design
PATH standardises what crosses a boundary between two organisations, and nothing else. Rails, custody, pricing, screens and ledgers belong to operators. A specification that reached into those would need renegotiating in every jurisdiction and would never ship.
INTEROP carries the envelope; the pillar owns the object. One URI grammar, one signature scheme, one reading algorithm, over objects that belong to different pillars. It is why adding a new kind of object does not mean inventing a new QR format.