A small, reproducible test bench

Test your JSON workflow with files that reveal real problems

Download a clean control, then try comments, line-delimited records, precision boundaries, duplicate names, invisible characters, and invalid input. Each file has a byte count, SHA-256 fingerprint, and a specific outcome to check.

Download the starter JSON Browse all 11 files

All files are synthetic and smaller than 1 KB. No personal data, generated gigabyte download, or script-driven fixture creation.

Use the same bytes everywhere

Run a fair check

Download a file and record its SHA-256 before comparing tools.
Choose the matching input mode: JSON, JSONC, NDJSON, or NDJSONC. A strict JSON parser is the control, not the universal oracle for relaxed formats.
Check the named operation below. Viewing a raw token, parsing it, querying it, and exporting it can produce different results.

Start with a clean control

Confirm the ordinary path before testing edge cases.

JSON

Nested orders

Check whether a viewer keeps array, object, and scalar boundaries clear.

Download nested-orders.json Open raw file

Size: 271 bytes, UTF-8
SHA-256: b6e7939d9f8179c79eecc4d28a6565a7098d85c88a415adf132a6393222cb4ad

Expected behavior by operation

Strict JSON parse: Accept one JSON document.
Format-aware open: Show two orders; the first has one nested item.
Query, convert, or export: Query $.orders[0].items[0].sku and expect pen. For CSV, choose or flatten fields first.

Nested JSON to CSV

Where formats diverge

A file extension and input mode matter as much as the text inside.

JSONC

Line and block comments

Catch cleanup code that mistakes // inside a URL for a comment.

Download comments.jsonc Open raw file

Size: 190 bytes, UTF-8
SHA-256: 6ea8d0eb029fe98e584cafa25f583d44939a7e2246ae542f437ba175c814876b

Expected behavior by operation

Strict JSON parse: Reject comments.
Format-aware open: A JSONC-aware reader accepts both comment styles and keeps the endpoint string unchanged.
Query, convert, or export: After a verified JSONC-to-JSON conversion, retry.attempts is 3 and the URL still ends in /v1//status.

JSON with comments

JSONC

Trailing commas

Separate JSONC reading from strict JSON or ordinary JQ acceptance.

Download trailing-comma.jsonc Open raw file

Size: 57 bytes, UTF-8
SHA-256: f13854ad432854a70fff75998bcfc2e989f4983e24fe5ce73ffa468a4fb790f0

Expected behavior by operation

Strict JSON parse: Reject the comma after query and the comma after true.
Format-aware open: A JSONC-aware reader can show features and enabled after accepting trailing commas.
Query, convert, or export: Remove both trailing commas for strict JSON or ordinary JQ; do not assume a comment-tolerant JQ path accepts this case.

JQ and JSONC limits

NDJSON

Three independent records

Distinguish line-delimited input from one JSON array.

Download events.ndjson Open raw file

Size: 120 bytes, UTF-8
SHA-256: f4e4ea9db649e033d66bc9788582c6042973292d64062e4a6351a7801d4f31af

Expected behavior by operation

Strict JSON parse: Reject the file as a single JSON document; each of its three lines parses separately.
Format-aware open: An NDJSON reader yields three records. JSON All-in-One normalizes recognized NDJSON into a workspace array.
Query, convert, or export: Filter records where ok is true and expect evt-1 and evt-3, in that order.

Open NDJSON files

NDJSONC

Relaxed records

Test a comment in one line and a trailing container comma in another.

Download events-with-comments.ndjsonc Open raw file

Size: 77 bytes, UTF-8
SHA-256: 9b48b61e4dcc14c6eed789eb5650db5a5295841848c61cf09b059f4c949d75e8

Expected behavior by operation

Strict JSON parse: Reject the file as one document; strict per-line JSON also rejects both records.
Format-aware open: An NDJSONC-aware reader yields two records, open then close.
Query, convert, or export: Export strict NDJSON only after removing the comment and trailing comma from each record.

NDJSON versus NDJSONC

Numbers that need a source check

Syntax validity does not guarantee exact arithmetic or round trips.

JSON

Integer past 2^53 - 1

Show the gap between an exact source token and a JavaScript Number.

Download unsafe-integer.json Open raw file

Size: 56 bytes, UTF-8
SHA-256: 91de0b1b646a5d0b5e610c132f681f77e1ac4237c3b6cd60f32fe06ac2cc3291

Expected behavior by operation

Strict JSON parse: Accept the numeric literal 9007199254740993.
Format-aware open: Inspect the source token, not just a converted numeric cell.
Query, convert, or export: JavaScript JSON.parse rounds id to 9007199254740992; exact_text retains 9007199254740993. Do not round-trip an ID through Number.

JSON number precision

JSON

Long decimal

Expose rounding during parsing, arithmetic, or export.

Download long-decimal.json Open raw file

Size: 110 bytes, UTF-8
SHA-256: ba8d29427a482dc6aee0245d7486f7546fa303bee9e4e1fec1a49b2958d3859a

Expected behavior by operation

Strict JSON parse: Accept the long decimal as a JSON number token.
Format-aware open: Compare the raw amount token with exact_text before any conversion.
Query, convert, or export: A JavaScript Number cannot retain all shown decimal digits. For exact decimal equality, compare the source token or a decimal-safe representation.

JSON number precision

Ambiguity and deliberate errors

A useful tool should make these conditions visible, not silently smooth them away.

JSON

Duplicate object names

Check whether a parser warns, rejects, or silently overwrites a name.

Download duplicate-keys.json Open raw file

Size: 43 bytes, UTF-8
SHA-256: fccb04376cb47b358840d0bc1acf999a1258da77f66cd814160cc703db4b5765

Expected behavior by operation

Strict JSON parse: JavaScript JSON.parse accepts the text and returns mode as second.
Format-aware open: The raw source contains two mode members; a parsed object may show only one.
Query, convert, or export: A parse-and-serialize round trip loses the first mode value. Do not use normalized output as proof the source had unique names.

Compare JSON files

JSON

Escaped invisible and Unicode characters

Inspect decoded code points without hiding control characters in the file itself.

Download unicode-invisible.json Open raw file

Size: 138 bytes, UTF-8
SHA-256: fc5d895ef11058f35e6618cca918c26e0bd63c03a8cd10cc5ccedd0bb002f10f

Expected behavior by operation

Strict JSON parse: Accept valid JSON escape sequences.
Format-aware open: The first decoded key starts with U+200B; precomposed and decomposed e-accent values can look alike but differ.
Query, convert, or export: Inspect code points before key comparison or normalization. The direction value includes U+202E and may render in a surprising order.

Find invisible characters

Invalid JSON

Incomplete literal

Exercise a precise parse error instead of accepting a partial object.

Download malformed-token.json Open raw file

Size: 28 bytes, UTF-8
SHA-256: e21143af8e456eebcb13f79d0fabab8d0bac94b66d3a8dfbfb90edebca6e0a44

Expected behavior by operation

Strict JSON parse: Reject tru because the only valid boolean token here is true.
Format-aware open: A validator should point to the bad token; do not treat the file as valid JSON.
Query, convert, or export: Fix tru to true before querying or exporting; no partial success should be presented as a validated document.

Open and validate JSON

Invalid JSON

Second root on the same line

Detect parsers that silently stop after the first complete value.

Download trailing-data.json Open raw file

Size: 28 bytes, UTF-8
SHA-256: 3cfc3c70de8c2d21796cfb41176dcd3d6dcb83dd4fa15bf05e459747b91c040d

Expected behavior by operation

Strict JSON parse: Reject extra non-whitespace text after the first object.
Format-aware open: Do not silently accept only {"ok":true}; both objects are on one line, so this is not valid NDJSON either.
Query, convert, or export: Split into separate NDJSON lines or wrap both objects in an array before continuing.

Open NDJSON files

Read the result, not the badge

What these files do not prove

These tiny files test behavior, not throughput, security, or overall product quality. Strict JSON syntax is separate from a reader's JSONC or record mode; preserving a number's source spelling is separate from exact arithmetic. A different tool may deliberately reject duplicates or relaxed input, and that can be a useful policy.

For larger, repeatable measurements, use the large JSON viewer benchmark methodology and record the generator, size, route, browser, and operation. We do not host a 1 GB fixture here.

Continue after a result

Work with a fixture

Use the tools index for available browser workflows, or paste two versions of a strict JSON fixture into the JSON diff tool. For local files, the file-opening guide explains the extension's file-access route.

Keep inspecting in JSON All-in-One

Open a fixture in the browser workbench, inspect its source and structured view, then choose a query or export only after checking the input mode.

Chrome

Edge

See the product overview