How is this different from a text diff?

A text diff compares line by line, so re-ordering keys or re-indenting a file shows up as a huge change even when the data is identical. This tool parses both sides into JSON values first, then compares the tree, so it reports real key-path changes (added / removed / changed) and ignores cosmetic formatting. Use a text diff for prose or code; use this for data.

Why does array order change the result?

By default arrays are compared position by position, because in JSON the order of array elements is usually meaningful (a list of steps, a sequence of events). So `[1,2,3]` vs `[3,2,1]` shows three changed indexes. If your array is really a set (tags, roles, IDs in any order), turn on "Ignore array order" and the two are treated as equal.

Can it compare very large JSON?

It handles typical API responses and config files (tens of thousands of nodes) comfortably because the diff is a single linear tree walk, not a quadratic line LCS. The practical ceiling is the URL share limit — the left/right inputs sync to the URL for sharing and that caps around 2000 characters, so very large payloads keep working in the tool but the share link will not carry them. Paste big blobs directly instead of relying on the link.

Does my JSON get uploaded anywhere?

No. Parsing and diffing are plain JavaScript in your browser tab. The only caveat is the shareable URL — if you click "Share link", your inputs are encoded in the query string, so do not share links for secrets. Copy the summary text instead when the data is sensitive.

Review an API response change before merging

A backend PR claims it "only adds a field" to the user endpoint. Capture the response before and after, paste the two payloads into the left and right boxes, and read the tree: if the only node is `+ data.user.timezone`, the claim holds; if you also see `~ data.user.role` changed or `- data.user.email` removed, you caught an unintended break. Copy the summary into the PR thread as evidence.

Diff two config or feature-flag snapshots

Production behaves differently from staging. Export both config JSONs, paste them in, and the diff shows exactly which flags differ — e.g. `~ flags.checkout.newFlow: false → true`. No eyeballing two 400-line files. Turn on "Sort keys before compare" if the two exporters emit keys in different orders.

Verify a data migration kept records intact

After transforming a records file, paste the source on the left and the migrated output on the right. Expected changes (a renamed key, an added `migratedAt`) should be the only nodes shown. Anything else — a dropped `items[3]`, a number coerced to a string — is a migration bug surfaced with its exact path.

Compare a fixture against a live response in tests

A snapshot test fails but the assertion message is a wall of text. Paste the expected fixture and the actual response here to see the three or four key paths that actually differ, instead of scrolling a diff that flagged the whole object because key order shifted. Enable "Ignore array order" when the endpoint returns an unordered collection.

Audit what a third-party webhook actually changed

A webhook fires twice with slightly different bodies. Drop both payloads in to see whether the second is a true update or a duplicate with a new `timestamp`. The changed-count badge tells you at a glance: one changed node means a heartbeat, a dozen means real state moved.

JSON Diff — Compare Two JSON Documents by Key Path

Structural JSON compare — added / removed / changed keys by path, three-colour tree, browser-only

Runs locally
Category Developer & DevOps
Best for Formatting, validating, shrinking, or inspecting code-adjacent text.

Left JSON (original)

Right JSON (compared)

Ignore array orderSort keys before compareTrim whitespace in strings

Added

Removed

Changed

Unchanged

Paste JSON on both sides to see a structural diff.

What this tool does

Free online structural JSON diff. Paste the original JSON on the left and the new JSON on the right; instead of comparing raw text lines, this tool parses both sides and walks the object/array tree, reporting exactly which key paths were added, removed, or changed — for example `user.address.city` changed from "Berlin" to "Munich", or `items[2]` was removed. That distinction matters: a text diff of two JSON files flags a whole line as different the moment a key is re-ordered or whitespace shifts, even though the data is identical. A structural diff sees through formatting, key order, and indentation, so you only get signal that reflects real data changes. Three options tune what counts as a change: ignore array order (compare arrays as unordered multisets, useful for tag lists or permission sets), sort keys before compare, and trim whitespace inside strings. The result is a colour-coded tree — cyan for added, pink for removed, violet for changed — plus a running count of each category and a one-click copyable summary you can paste into a code review or bug report. If either side is not valid JSON, you get a clear message saying which side failed and the parser error, so you fix the typo instead of guessing. Everything runs in your browser tab; neither payload is uploaded, which makes it safe for API responses, config files, and feature-flag snapshots that should not leave your machine.

Tool details

Input: Text + Structured content; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 12 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Developer & DevOps · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How JSON Diff fits into your work

Use it in the small gaps between coding, reviewing, debugging, and shipping.

Developer jobs

Formatting, validating, shrinking, or inspecting code-adjacent text.
Preparing snippets for documentation, tickets, commits, or handoff.
Checking a small payload quickly without switching tools.

Developer checks

Run irreversible transforms like minify or obfuscate on a copy.
Keep secrets out of pasted snippets unless the tool explicitly stays local.
Use your normal tests or linter before shipping transformed code.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Review an API response change before merging
A backend PR claims it "only adds a field" to the user endpoint. Capture the response before and after, paste the two payloads into the left and right boxes, and read the tree: if the only node is `+ data.user.timezone`, the claim holds; if you also see `~ data.user.role` changed or `- data.user.email` removed, you caught an unintended break. Copy the summary into the PR thread as evidence.
Diff two config or feature-flag snapshots
Production behaves differently from staging. Export both config JSONs, paste them in, and the diff shows exactly which flags differ — e.g. `~ flags.checkout.newFlow: false → true`. No eyeballing two 400-line files. Turn on "Sort keys before compare" if the two exporters emit keys in different orders.
Verify a data migration kept records intact
After transforming a records file, paste the source on the left and the migrated output on the right. Expected changes (a renamed key, an added `migratedAt`) should be the only nodes shown. Anything else — a dropped `items[3]`, a number coerced to a string — is a migration bug surfaced with its exact path.
Compare a fixture against a live response in tests
A snapshot test fails but the assertion message is a wall of text. Paste the expected fixture and the actual response here to see the three or four key paths that actually differ, instead of scrolling a diff that flagged the whole object because key order shifted. Enable "Ignore array order" when the endpoint returns an unordered collection.
Audit what a third-party webhook actually changed
A webhook fires twice with slightly different bodies. Drop both payloads in to see whether the second is a true update or a duplicate with a new `timestamp`. The changed-count badge tells you at a glance: one changed node means a heartbeat, a dozen means real state moved.

Common pitfalls

Expecting a text diff. This tool ignores key order and indentation by design — if you actually want to see whitespace and line changes (for a code file, not data), use the Text Diff tool instead.
Leaving "Ignore array order" off for set-like arrays. A list of tags or roles in a different order shows as many changed indexes. Turn the option on when position is not meaningful, or you will chase phantom changes.
Pasting JSON5, comments, or trailing commas. The parser is strict JSON. A `// comment` or a trailing comma makes the side invalid; format it through the JSON Formatter first.

Privacy

Parsing and the tree diff are plain JavaScript that runs in your browser tab — neither the left nor the right JSON is uploaded, logged, or analysed. The one caveat is URL state: the left/right inputs sync to the query string so you can share a diff, which means a "Share link" carries your data into the recipient's browser history and any server access log along the way. For API keys, tokens, or unreleased payloads, copy the text summary instead of sharing the URL.

FAQ

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JSON Diff — Compare Two JSON Documents by Key Path

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How JSON Diff fits into your work

Developer jobs

Developer checks

Good next steps

Real-world use cases

Review an API response change before merging

Diff two config or feature-flag snapshots

Verify a data migration kept records intact

Compare a fixture against a live response in tests

Audit what a third-party webhook actually changed

Common pitfalls

Privacy

FAQ

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