Text Comparison
The /diff endpoint compares two texts and returns an ordered list of changes, line by line or word by word.
POST/v6/diff
How it works?
The comparison relies on the Longest Common Subsequence (LCS) algorithm: it finds the largest set of segments shared by both texts in the same order, and everything outside that set is reported as added or removed. In line mode the texts are split on newlines, keeping empty lines; in word mode they are split on whitespace runs and empty segments are dropped.
Parameters
The request body must be JSON:
| Parameter | Required | Description |
|---|---|---|
a | Yes | Original text |
b | Yes | Modified text, compared against a |
mode | No | Comparison granularity: line or word. Default: line |
Available Modes
| Mode | Description |
|---|---|
line | Splits both texts on newlines and compares line by line |
word | Splits both texts on whitespace and compares word by word |
Response Fields
| Field | Type | Description |
|---|---|---|
mode | string | Granularity used: line or word |
added | number | Number of segments present only in b |
removed | number | Number of segments present only in a |
changes | object[] | Ordered changes rebuilding b from a |
changes entries:
| Field | Type | Description |
|---|---|---|
type | string | equal, add or del |
value | string | The line or word this change applies to |
Code Examples
curl -X POST \
-H "Content-Type: application/json" \
-d '{
"a": "line1\nline2",
"b": "line1\nline2 edited"
}' \
"https://api.sylvain.sh/v6/diff"Try It
Error Handling
If parameters are missing or invalid, the API will return an error:
| Error Message | Description |
|---|---|
Please provide a first text (a={text}) | The a parameter is missing or is not a string |
Please provide a second text (b={text}) | The b parameter is missing or is not a string |
Texts must be 10000 characters or fewer | a or b exceeds the maximum length |
Mode must be one of: line, word | The mode value is not line or word |
Texts must contain 2000 lines or fewer | A text has more lines than the limit in line mode |
Texts must contain 2000 words or fewer | A text has more words than the limit in word mode |