JSONPath & JMESPath Tester

About the JSONPath & JMESPath Tester

Paste a JSON document and type a query: the result updates as you type. JSONPath follows RFC 9535, the IETF standard — every match is listed with its normalized path ($['store']['book'][0]), marked in the document, and one click selects it in the editor. JMESPath follows jmespath.py, the implementation behind the AWS CLI's --query option, so you can build a query here and copy it straight into your shell.

Both languages are interpreted, never run as code, and both implementations pass every case of their official test suites: the JSONPath Compliance Test Suite and the JMESPath compliance tests. Numbers keep every digit, and the page works offline once loaded — nothing you paste leaves your device.

Common uses

• Working out a JSONPath for an API test, a Kubernetes or OpenAPI tool, or a database that implements RFC 9535.
• Building an aws … --query or az … --query expression against a saved response before running it for real (the Azure CLI uses JMESPath too).
• Finding where values sit in a large document: every JSONPath match comes with its exact path.
• Checking whether an expression written for another JSONPath library is standard RFC 9535.

JSONPath (RFC 9535) in short

A query starts with $, the whole document, followed by steps: .name or ['name'] for an object member, [0] or [-1] for an array element, [1:3] for a slice, * for every child and .. for every depth. [?…] keeps the children for which a filter is true; inside it @ is the child being tested: $..book[[email protected] < 10 && @.category == 'fiction']. Filters can test that something exists ([[email protected]]), compare values, and call five functions: length(), count(), match(), search() and value().

RFC 9535 is stricter than many older JSONPath libraries, and this tester reports their syntax as errors rather than guessing: script expressions such as [(@.length-1)] (write [-1]), =~ (use match() or search()), in, and .length as a property (use length() in a filter). Comparisons need singular queries — @.a, @['b'][0] — because a query such as @.tags[*] can select several values; use count() or value() for those.

Regular expressions in match() and search()

match() succeeds when the whole string matches the pattern, search() when part of it does. Patterns are I-Regexp (RFC 9485), a small subset that works the same everywhere: characters, ., […] classes, *, +, ?, {n,m}, |, groups and Unicode categories such as \p{Lu}. There is no \d, \w or \s (write [0-9]), no look-ahead and no back-references, and . does not match a line break. A pattern that is not valid I-Regexp makes the function false, as the standard says. Queries stop after 3 seconds, so a pattern that backtracks badly cannot freeze the page.

JMESPath as in the AWS CLI

Reservations[] flattens a list and [*] and .* project over lists and objects: the rest of the expression is applied to each item, and items that give null are dropped. A pipe | stops the projection. [?State.Name=='running'] filters, {id: InstanceId} and [a, b] build new objects and lists, 'text' is a string, and JSON literals go in backticks. A missing field gives null rather than an error.

This tester follows jmespath.py, the library the AWS CLI uses: < and > also compare strings, the 26 built-in functions (sort_by(), max_by(), join(), to_number()…) have the same type rules and error cases, and the numbers they compute are written as Python writes them — the average of 2 and 4 is 3.0.

JSONPath or JMESPath?

• JSONPath selects parts of a document and tells you where they are; it is an IETF standard, which makes it a good choice for configuration, tests and APIs that must behave the same in every language.
• JMESPath reshapes data: projections, multi-select lists and hashes, pipes and functions turn a large response into exactly the list or table you want, which is why the AWS and Azure command-line tools use it for --query.

Limitations

• Only standard syntax is accepted: extensions of other JSONPath libraries (Jayway, JSONPath-Plus) and of the newer "JMESPath Community" edition (let expressions, arithmetic) are reported as errors.
• The document must be strict JSON; comments, trailing commas or single quotes are reported with their line and column.
• Matches are highlighted in documents up to 400 KB and listed up to 2,000; every match is counted, and Values, Copy and Download contain all of them — up to 20 million characters, beyond which the tester asks for a narrower query instead of running out of memory.
• A query that takes longer than 3 seconds is stopped.

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