Is this the full jq language?

No. This tool supports a practical subset: ., .field, .[n], .[] stream expansion, a fixed set of builtins (length, keys, values, type, first, last, sort, reverse, min, max, add), and | pipes between segments. It does not support jq's object/array construction syntax, arithmetic, string interpolation, conditionals, or custom functions.

What happens with a filter that isn't in the supported subset?

The tool returns a clear error explaining the filter is unsupported and lists exactly what accessors and builtins are available, rather than trying to guess at a partial result.

Does .[] work the same as real jq?

Yes for the common case: applied to an array it streams each item, applied to an object it streams its values, and later pipe segments apply to every streamed item, mirroring how jq's .[] works for the array and object cases this tool supports.

Can I chain multiple builtins together?

Yes, with | pipes, for example .users | length or .scores | sort | first both work since each pipe segment is evaluated in order against the previous segment's result.

Run jq Online - JSON Filter Playground (Practical Subset)

Overview

Introduction

jq is the standard command-line tool for slicing and filtering JSON, but installing it isn't always an option, and its full language is large.

This tool implements a practical, well-defined subset of jq's filter syntax that runs entirely in the browser, covering the accessors and builtins people reach for most often.

What Is jq Playground?

A jq-style filter evaluator supporting identity (.), field access (.name), index access (.[0]), the .[] stream operator, a fixed list of builtins, and | pipes chaining segments together.

It is explicitly not a full jq implementation, there's no arithmetic, string interpolation, object/array construction, conditionals, or user-defined functions.

How jq Playground Works

The filter is split on | into segments, each segment is either a recognized builtin name or an accessor chain tokenized into field/index/stream steps using a fixed grammar.

Segments are applied left to right against the running value (or, once .[] has streamed, against every item in the running array), and any segment that doesn't match the supported grammar produces an explicit unsupported-filter error rather than a silent wrong answer.

When To Use jq Playground

Use it for quick, common JSON filtering tasks, pulling a nested field, listing array items, counting entries, when you don't have jq installed or don't want to leave the browser.

It's also a fast way to sanity-check a simple jq-style expression before dropping it into a script that has real jq available.

Often used alongside JSONPath Tester, JSON Value Extractor and JSON Key & Value Finder.

Features

Advantages

Runs entirely client-side with no installation.
Covers the accessor patterns and builtins used in the vast majority of everyday jq one-liners.
Fails loudly with a specific message on unsupported syntax instead of silently misinterpreting it.

Limitations

No arithmetic, string interpolation, object/array construction (map, select with expressions, {} construction), conditionals, or custom functions, this is a fixed subset, not the jq language.
The builtin list is fixed to length, keys, values, type, first, last, sort, reverse, min, max, and add; anything else (e.g. select(), map(), sub()) is unsupported.

Examples

Extracting a nested field

Input

{"users":[{"name":"Ada"},{"name":"Grace"}]}

Output

[
  "Ada",
  "Grace"
]

Filter .users[].name streams each user object with .[] and then extracts .name from every streamed item.

Unsupported filter

Input

{"a":1}

Output

Unsupported jq expression. This tool supports: ., .field, .[n], .[], keys, length, values, type, first, last, sort, reverse, min, max, add, and | pipes.

A filter like .a + 1 uses arithmetic, which is outside this tool's supported subset, so it returns an explicit error instead of a wrong answer.

Best Practices & Notes

Best Practices

Build up a filter one pipe segment at a time, testing each step, since the tool reports exactly which point in the pipeline failed.
Use .[] before a field access (e.g. .items[].id) to pull the same field out of every array item at once.
Fall back to real jq or a script for anything involving arithmetic, conditionals, or object construction.

Developer Notes

The evaluator tracks a JqState with either a single running value or, once .[] has been hit, a streamed array of values; every subsequent step maps over that array instead of the single value, which keeps the streaming semantics correct without needing a generator-based evaluation model.

jq Playground Use Cases

Quickly pulling a nested field out of an API response without installing jq
Listing or counting items in a JSON array
Sanity-checking a simple jq expression before using it in a script with real jq

Common Mistakes

Assuming full jq syntax (select(), map(), string interpolation) will work, only the documented subset is supported.
Forgetting | between pipeline segments, e.g. writing .users[] .name instead of .users[] | .name.
Expecting arithmetic like .price * 1.1 to work, this subset has no arithmetic operators.

Tips

Start a filter with .[] to stream an array or object's values before chaining further accessors.
Check the FAQ for the exact builtin list if a filter you expect to work returns the unsupported-expression error.

jq Playground