Diff markdown API

Line-oriented added / removed / unchanged.

POST /api/v1/diff returns a line-oriented diff between two markdown documents tagged added / removed / unchanged. Perfect for editorial review UIs and AI editing pipelines.

Overview

Line-by-line diff between two markdown documents. Each entry is tagged `added`, `removed`, or `unchanged` — ready for inline review UIs, content-review tools, and AI editing feedback loops.

Request

Authenticate with Authorization: Bearer YOUR_API_KEY and send a JSON body containing the parameters below. Pick your language:

curl -X POST 'https://trymarkdownviewer.com/api/v1/diff' \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"left":"Hello world\n","right":"Hello there\n"}'

Body parameters

Field	Type	Required	Description
left	string	required	Original markdown.
right	string	required	Updated markdown.

Response

Success responses are wrapped in a data field. Errors use { error: { code, message } } with an appropriate HTTP status — see the error reference.

{
  "data": {
    "diff": [
      {
        "type": "removed",
        "value": "Hello world"
      },
      {
        "type": "added",
        "value": "Hello there"
      }
    ],
    "added": 1,
    "removed": 1,
    "unchanged": 0
  }
}

Use cases

Editorial review

Render a side-by-side review UI for content changes.

AI editing

Inspect exactly what an LLM changed in a document.

Try in browser

Free tools that run the same logic locally — no API key, no upload.

Markdown Diff Tool
Line-by-line compare

Try it

Send a real request against your account in the API playground. Errors there link straight back to the error reference.