JSON tools
Start with the age filter. Run explicitly with the button or Ctrl/Cmd+Enter; editing makes the previous result out of date.
Preview is displayed in 5,000-character blocks. Copy and download include the complete result.
JSON and expressions stay in browser memory; they are not saved.
Official jmespath.js 0.16.0 · Safety patches · 26 standard functions
Result is out of date; copy and download are disabled.
A JMESPath tester is useful when a cloud response contains dozens of fields but the next step needs only names, counts or a smaller object. Test the selection against actual JSON before moving an expression into your script.
This JMESPath evaluator gives one JSON result, which may be an array, an object or a scalar. Use the JMESPath playground examples to compare a projection with an object constructor; their output shapes matter as much as the selected values.
Keep people whose age meets a numeric condition, then select their names. A projection applies the following expression to each array element; it can omit null results, so the output count need not equal the input count.
Create objects with named fields, sort records by a property or calculate a count. The JMESPath tester shows the resulting JSON directly, allowing you to check whether the next command will receive a list or a single object.
Paste strict JSON or import a local file. Files are limited to 500,000 bytes and decoded input to 500,000 characters. Importing, clearing and loading a sample show a replacement preview; one undo restores the previous input, expression and result. Files must be valid UTF-8; a BOM is not removed automatically and fails JSON validation.
Evaluation is manual. Ctrl/Cmd+Enter also runs the query. Choosing a query example changes the expression without executing it, and any edit disables export until a fresh query succeeds.
null, false, 0, an empty string and [] can all be successful results. The preview grows in blocks of 5,000 characters; copying and downloading include the full accepted JSON, not only the visible portion.
Use people[?age >= `18`].name for a numeric filter. Backticks mark JSON literals; a quoted raw string such as 'active' is a string value. Comparing a number to a string does not turn them into the same type.
A multiselect object such as {names: people[].name, count: length(people)} creates a new structure without changing the source. Multiselect lists preserve positions and can retain null values that a projection would omit.
A pipe passes the completed left result to the expression on the right. Use sort_by, length, contains or sum with their required argument types; function references such as &age are expressions, not property-name strings.
JSON validation, expression syntax, unknown functions, argument count and argument type failures are reported as errors. A missing property may produce null without a failure; the result remains available to export.
Yes: paste JSON output from AWS CLI and test the expression against that document. This does not connect to AWS. CLI version differences and shell quoting still need checking when you move the expression back to your command.
No. Start with a field such as people, or use @ for the current value. The $ root prefix belongs to JSONPath and is not a prefix to add to a JMESPath expression.
For the example document, use people[?age >= `18`].name. The number is a JSON literal between backticks. Check that age is numeric; a string containing digits is a different type.
A property lookup returns null when the key is absent. An explicit null can produce the same output, while a filter with no retained elements normally produces []. A successful null result is not a syntax error.
Yes. This JMESPath tester runs official jmespath.js 0.16.0 with safety patches, rather than matching a few expressions with a custom parser. It exposes the standard 26 functions, not community extensions.
Found a query this tool handles incorrectly?
Run the JMESPath tester on the sample, change one condition and compare the result before applying the expression to a larger response.