Text Diff API

Q: Can I get a git-style unified diff?

Yes. In the default `lines` mode the `unified` field always contains the patch; for other modes add `unified=true`.

Q: How do I compare two JSON objects?

Use `mode=json` with both documents as JSON strings in `a` and `b`. They are pretty printed and compared line by line, so formatting differences are ignored.

Compare two texts by lines, words, characters, sentences or JSON and get the changes, a similarity score and a unified diff patch.

POSThttps://apibox.io.vn/v1/text-diff

Text▶ Try it online

Send the original text in a (or old) and the new text in b (or new). The API returns the list of changes (each one added, removed or unchanged with its value), stats with added, removed and unchanged counts, a similarity percentage and identical when nothing changed.

Choose the granularity with mode: lines (default, counts lines and also returns a unified diff like git diff), words, chars, sentences, or json which compares two JSON documents structurally after pretty printing. ignore_case and ignore_whitespace relax the comparison. For other modes, unified=true adds the patch; a_name, b_name and context (0-50 lines, default 3) control its header and context.

Both texts together may contain up to 2,000,000 characters (request body up to 4 MB).

Parameters

Name	In	Type	Required	Default
`a`	body	string	yes		Original text. Alias: `old`.
`b`	body	string	yes		New text. Alias: `new`.
`mode`	body\|query	string	no	`lines`	Comparison unit: `lines`, `words`, `chars`, `sentences` or `json`.
`ignore_case`	body\|query	boolean	no	`false`	Ignore upper/lower case differences (lines, words, chars).
`ignore_whitespace`	body\|query	boolean	no	`false`	Ignore leading/trailing whitespace in lines mode, and whitespace changes in words mode.
`unified`	body\|query	boolean	no	`false`	Also return a unified diff for modes other than lines (always included in lines mode).
`context`	body\|query	number	no	`3`	Context lines in the unified diff (0-50).
`a_name`	body\|query	string	no	`a`	File name of the original in the unified diff header.
`b_name`	body\|query	string	no	`b`	File name of the new text in the unified diff header.

Example

curl -X POST "https://apibox.io.vn/v1/text-diff" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"a":"one\ntwo\nthree","b":"one\n2\nthree\nfour"}'

const res = await fetch('https://apibox.io.vn/v1/text-diff', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "a": "one\ntwo\nthree",
    "b": "one\n2\nthree\nfour"
  }),
});
const data = await res.json();
console.log(data);

import requests

res = requests.post(
    "https://apibox.io.vn/v1/text-diff",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={"a": "one\ntwo\nthree", "b": "one\n2\nthree\nfour"},
    timeout=30,
)
print(res.json())

<?php
$ch = curl_init('https://apibox.io.vn/v1/text-diff');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_HTTPHEADER => ['Authorization: Bearer YOUR_API_KEY', 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS => '{"a":"one\\ntwo\\nthree","b":"one\\n2\\nthree\\nfour"}',
]);
$response = curl_exec($ch);
print_r(json_decode($response, true));

Response

{
  "mode": "lines",
  "identical": false,
  "similarity": 50,
  "stats": {
    "added": 2,
    "removed": 1,
    "unchanged": 2,
    "unit": "lines"
  },
  "changes": [
    {
      "type": "unchanged",
      "value": "one\n",
      "count": 1
    },
    {
      "type": "removed",
      "value": "two\n",
      "count": 1
    },
    {
      "type": "added",
      "value": "2\n",
      "count": 1
    },
    {
      "type": "unchanged",
      "value": "three\n",
      "count": 1
    },
    {
      "type": "added",
      "value": "four\n",
      "count": 1
    }
  ],
  "unified": "===================================================================\n--- a\n+++ b\n@@ -1,3 +1,4 @@\n one\n-two\n+2\n three\n+four\n"
}

Use cases

Show what changed between two versions of a document or contract
Compare API responses or JSON configs in tests
Generate unified diff patches from a backend
Measure how similar two texts are (plagiarism, deduplication)

FAQ

Can I get a git-style unified diff?

Yes. In the default lines mode the unified field always contains the patch; for other modes add unified=true.

How do I compare two JSON objects?

Use mode=json with both documents as JSON strings in a and b. They are pretty printed and compared line by line, so formatting differences are ignored.

How is similarity calculated?

Unchanged units divided by unchanged plus the larger of added or removed, as a percentage. Units are lines in lines/json mode and characters otherwise.

Related APIs

a-b

Text Diff API

Parameters

Example

Response

Use cases

FAQ

Related APIs

Slugify

Text Statistics

Case Converter