RFC 9535 is the 2024 IETF standard that finally specifies JSONPath formally, ending years of divergent implementations. It defines the root identifier $, child segments, the descendant segment .., wildcards, array slices, filter selectors and a small set of function extensions like length() and count().

What is recursive descent in JSONPath?

The descendant segment, written .., searches the current node and all of its descendants at any depth. For example $..price selects every price field anywhere in the document, no matter how deeply nested. It is powerful but can be slow on large documents.

How do filter expressions work?

A filter selector ? keeps only the items for which the expression is true. Inside the filter, @ refers to the current item, so $.items[?@.price < 10] selects items whose price is under 10. Filters support comparison, &&, || and existence tests.

What is the difference between $ and @ in JSONPath?

$ is the root of the whole document and starts every JSONPath query. @ is the current node being tested and is only valid inside a filter expression. Use $ to reach back to the document root from within a filter, and @ to reference the item under evaluation.

Does JSONPath array slicing match Python?

Yes, RFC 9535 slices follow Python semantics: [start:end:step] is half-open, supports negative indices counting from the end, and a default step of 1. For example [1:3] selects indices 1 and 2, and [::-1] reverses the array.

JSONPath Syntax Reference

Q: What is the difference between $ and @ in JSONPath?

$ is the root of the whole document and starts every JSONPath query. @ is the current node being tested and is only valid inside a filter expression. Use $ to reach back to the document root from within a filter, and @ to reference the item under evaluation.

Q: Does JSONPath array slicing match Python?

Yes, RFC 9535 slices follow Python semantics: [start:end:step] is half-open, supports negative indices counting from the end, and a default step of 1. For example [1:3] selects indices 1 and 2, and [::-1] reverses the array.

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JSONPath is a query language for JSON, the JSON equivalent of XPath for XML. It lets you select nodes from a JSON document with a compact path expression. After years of incompatible implementations, IETF RFC 9535 (2024) standardised the syntax. This reference lists the standard segments and selectors with examples.

How it works

Every JSONPath starts at the root identifier $. You then chain segments that each narrow or expand the set of selected nodes: .name or ['name'] for a child, [*] for every element, .. to descend into all descendants, [0] or [1:3] for array indices and slices, and ?<expr> to filter. Inside a filter, @ refers to the item currently being tested. The engine evaluates the path left to right, producing a node list.

Worked example

Given this document:

{ "store": { "books": [
  { "title": "A", "price": 8 },
  { "title": "B", "price": 15 }
] } }

$.store.books[*].title selects ["A", "B"]
$..price selects [8, 15] (recursive descent)
$.store.books[[email protected] < 10].title selects ["A"] (filter)

Notes and tips

Recursive descent .. is convenient but scans the whole subtree, so prefer an explicit path on large documents. Filter comparisons are type-aware: comparing a string to a number is simply false rather than an error. Use length() and count() function extensions for size-based filters, e.g. $.items[?length(@.tags) > 0].