JSON Pointer Explained: Paths, Arrays and Escaped Keys
Learn JSON Pointer syntax, including /0 array indexes, ~0 and ~1 escaping, and the empty root pointer.
JSON Pointer identifies one value inside a JSON document. It is useful in validation errors, patch operations, and tools that need a stable reference to a nested field. A pointer is a location, not a search expression: it does not provide wildcards or filters.
Read segments from left to right
The empty string identifies the whole document. A slash starts each segment, so /user/name selects name inside user. A pointer consisting of just / selects an object property whose name is the empty string. For arrays, /items/0 selects the first element. Array indexes do not use square brackets and should not have leading zeros.
Escape property names in the right order
Replace tilde with ~0 and slash with ~1 when constructing a segment. When decoding, replace ~1 first and ~0 second. Reversing that decoding order can interpret ~01 incorrectly. A key named a/b is addressed by /a~1b; a key named m~n is addressed by /m~0n. Dots and spaces are ordinary characters in a pointer string.
Separate pointers from URI fragments
A URI fragment representation starts with # and may need percent encoding in addition to pointer escaping. Do not assume a URL-encoded string can be used directly as a plain pointer. A pointer that is syntactically valid can still fail to resolve when a property is absent. Report that condition separately from malformed escape sequences when building an API or validation interface.
Worked example
{"a/b":{"m~n":[42]}}
Pointer: /a~1b/m~0n/0
Selected value: 42Is JSON Pointer the same as JSONPath?
No. JSON Pointer addresses a specific location. JSONPath is a query language with selectors and filtering capabilities.
Reference and further reading
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Parse NDJSON line by line, diagnose malformed records, and preserve useful error locations during imports.