Json Compare

Tool Overview

This JSON compare tool shows the differences between two JSON documents. You paste or type one JSON in the first box and another in the second box. The tool parses both, compares them by structure and value, and lists what was added, removed, modified, or ignored. You see a summary count and a list of changes with the path to each difference.

Developers and others often need to see what changed between two API responses, config files, or data exports. Reading two large JSON blobs by eye is slow and error prone. This tool solves that by walking both structures and reporting added keys, removed keys, and changed values at each path so you can scan the list quickly.

The tool is for anyone who works with JSON. Developers use it to compare API responses or configs. You do not need to be an expert. You paste two JSON texts, choose ignore rules if you want, and read the summary and the list of changes. Optional AI explanation can summarize the differences in plain language.

Background & Concept Explanation

JSON is a format for nested data. It has objects with keys and values, arrays with ordered elements, and primitive values like numbers and strings. Comparing two JSON documents means walking both structures together and noting where a key or array index exists only in one (added or removed), or where the value at the same path is different (modified). The path is the route to that spot, for example root, or user.name, or items[0].id. A related operation involves formatting JSON data as part of a similar workflow.

JSON comparison is used in many places. Developers compare API responses before and after a change. They compare config files or environment files. They check two data exports to see what was added or removed. Without a tool you would have to diff the raw text (which is hard when keys are reordered) or write a script. This tool does the structural comparison for you.

People struggle when they compare JSON by hand. Nested objects and arrays are hard to align. Keys that appear in one document but not the other are easy to miss. Some fields like timestamps or IDs change every time and clutter the result. This tool walks the structure and reports each difference with its path. You can turn on ignore rules so that certain keys (for example id or timestamp) are skipped and not counted as differences. That way the list focuses on the changes that matter to you.

The tool runs in your browser. Parsing and comparison are done locally. Only if you ask for an AI explanation are the list of differences sent to a backend. The comparison itself does not send your JSON to a server. For adjacent tasks, comparing text content addresses a complementary step.

Key Features

• Two text areas let you enter the first JSON (JSON A) and the second JSON (JSON B). You paste or type in each box. Each box has a character limit of 500000 characters. A counter shows how many characters are left; when you are close to the limit it turns red. This keeps the tool responsive and avoids overload.
• Comparison runs automatically when you change either JSON. The tool tries to parse both as JSON. If either is invalid, that side shows an error and no comparison is run. If both are valid, the tool compares them and updates the result. You do not need to click a compare button. This gives you instant feedback as you edit or paste.
• Ignore rules let you hide certain paths from the comparison. You choose a preset with buttons. No Rules means every path is compared. API Response ignores paths that match common metadata such as id, uuid, createdAt, updatedAt, and timestamp. Config Files ignores paths matching version, hash, and buildDate. When a path is ignored, it is not counted as added, removed, or modified; it appears in the summary as ignored and in the list with type Ignored. This reduces noise when you only care about meaningful data changes.
• The summary shows four counts. Added is how many paths exist only in the second JSON. Removed is how many exist only in the first. Modified is how many paths exist in both but have different values. Ignored is how many paths were skipped by the ignore rules. These numbers give you a quick sense of how different the two documents are.
• The changes list shows each difference as a row. Each row has the path (for example user.email or items[2].name), a badge for the type (Added, Removed, Modified, or Ignored), and for Modified rows a short preview of the old value and the new value. You can click a row; in the current tool the click is logged and can be used later to scroll or highlight. The list is scrollable and limited in size so the interface stays responsive. This lets you go through differences one by one and see exactly where and what changed.
• View mode lets you switch between Inputs and Results. On large screens you can show mainly the two input boxes or mainly the results panel. This helps when you want to focus on editing JSON or on reading the diff.
• Clear removes both JSON texts and the result. You can start over with a new pair of documents. Optional AI explanation sends the list of differences (not the full JSON) to a backend and shows a short explanation in plain language. You click a button to request it. If it fails, you may see an error such as insufficient credits. The comparison and summary do not depend on the AI; they work without it.
• Invalid JSON is detected. If you paste or type something that is not valid JSON in one or both boxes, the tool shows an error for that box and does not run the comparison. When both are valid, the comparison runs. This prevents confusing results from malformed input.
• Deep nesting and very long lists are limited. The comparison engine stops recursing after a certain depth and stops adding entries after a maximum number of differences. So extremely large or deeply nested JSON may not show every difference; you will still see a partial list and the summary. This avoids freezing the browser.

Common Use Cases

Developers compare two API responses. They paste the old response in JSON A and the new response in JSON B. They use the API Response ignore preset so that id, createdAt, and similar fields do not clutter the list. They read the summary and the changes list to see what was added, removed, or modified in the data.

Config or environment files are often JSON. You can paste two versions and compare them. Use Config Files preset to ignore version or build metadata. The path list shows exactly which key changed and, for modified entries, the old and new value.

Data exports can be compared to see what records or fields were added or removed. Paste the old export in one box and the new export in the other. The tool walks the structure and reports differences. For very large files you may hit the entry limit; the summary and first part of the list still give useful information. When working with related formats, removing duplicate lines can be a useful part of the process.

Anyone debugging a change in JSON output can paste the expected and actual JSON and use the tool to see where they differ. The path and the old and new value for modified entries help pinpoint the issue. Optional AI explanation can summarize the diff in plain language.

How to Use This Tool

1. Open the JSON compare tool in your browser.
2. Paste or type the first JSON in the box labeled JSON A. Paste or type the second JSON in the box labeled JSON B. Each box accepts up to 500000 characters. Watch the character counter if you paste very long text.
3. Check for errors. If either box shows Invalid or Invalid JSON Syntax, fix the JSON in that box. The tool only runs the comparison when both inputs are valid JSON.
4. Choose ignore rules. Click No Rules for a strict comparison of every path. Click API Response to ignore common metadata keys such as id and timestamp. Click Config Files to ignore version, hash, and buildDate. The comparison updates automatically when you change the preset.
5. Read the summary. In the Results area you see four numbers: Added, Removed, Modified, and Ignored. Use them to see how different the two documents are.
6. Read the changes list. Below the summary, each difference is listed with its path and type. For Modified entries you see a short preview of the old and new value. Scroll through the list and click a row if the tool supports navigation. The list may be capped for very large diffs.
7. Switch view if needed. Use the Inputs and Results buttons to focus on the input boxes or on the result panel.
8. Optionally click Generate Explanation to get an AI-written summary of the differences. Wait for the response. If you see an error such as insufficient credits, the comparison and list are still valid. You can reset the explanation and try again later.
9. To compare a new pair of JSON documents, click Clear. Both boxes and the result are reset. Paste or type the new JSON and repeat.

Calculations & Logic

The tool parses each input with JSON.parse. If parsing fails, that input is treated as invalid and no comparison is run. When both parse successfully, the tool walks both structures together. It starts at the root and compares type and value. If the two values are equal (including null), nothing is added to the list. If one is null or the types differ, the path is reported as Modified with the old and new value. For two objects, it collects all keys from both, then for each key: if the key is only in the second object, the path is Added; if only in the first, Removed; if in both, it recurses into the values at that path. For two arrays, it iterates by index from 0 to the maximum length; if an index is only in the second array, that path is Added; if only in the first, Removed; if in both, it recurses. For two primitives that are not equal, the path is Modified. Before comparing a path, the tool checks ignore rules: each rule is turned into a regex (with wildcards allowed) and tested against the path; if any rule matches, the path is reported as Ignored and the summary ignored count is increased. Recursion is stopped at a fixed maximum depth and the list of entries is capped at a maximum size so that very large or deep JSON does not hang the browser. The summary counts are updated as each entry is added. The result is the summary plus the list of entries (paths and types and, where relevant, old and new values).

Reference Tables or Scales

Ignore presets: In some workflows, finding and replacing text is a relevant follow-up operation.

Difference types:

Limits:

Tips, Limitations & Best Practices

Use the API Response or Config Files preset when you compare API responses or configs so that timestamps and IDs do not dominate the list. Use No Rules when you need to see every difference including metadata. For related processing needs, encoding data in Base64 handles a complementary task.

Ensure both inputs are valid JSON. The tool does not fix or guess; invalid JSON shows an error and no comparison. Remove trailing commas, fix quotes, and check brackets and braces if you see Invalid JSON Syntax.

Very large or deeply nested JSON may hit the entry limit. You will see the first part of the list and the summary. For a full diff on huge documents consider splitting the data or using a desktop tool.

AI explanation is optional and can fail. You may see an error about credits or connection. The comparison and the list of changes do not depend on it. You can use the tool fully without ever requesting an explanation.

Paths use dot notation for keys and bracket notation for array indices, for example user.name and items[0]. Use the path to locate the difference in your JSON. Clear when you are done so you can paste a new pair without leftover content.