Text diff API: line-by-line comparison of two texts

$0.01 per call · failed calls are never charged · no account or subscription: pay per call with a card key or USDC

Line-by-line difference between two texts: each line marked as unchanged, removed or added, with counts. Use to see what changed between two versions of a document, config or prompt.

When to use it

Run it free (25 free calls) Buy credits by card (from $1) Example result (JSON)

Try it with your own inputs

The original text
The new text

Uses one of your 25 free calls. Nothing is charged, and a call that fails is not counted.

Inputs

NameTypeDescription
a (required)stringThe original text
b (required)stringThe new text

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://tools.funwords.eu/text/diff?a=one%0Atwo%0Athree&b=one%0A2%0Athree%0Afour"

Or one of your 25 free calls, no key:

curl "https://tools.funwords.eu/text/diff?a=one%0Atwo%0Athree&b=one%0A2%0Athree%0Afour&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "added": 2,
  "removed": 1,
  "unchanged": 2,
  "lines": [
    {
      "op": "=",
      "line": "one"
    },
    {
      "op": "-",
      "line": "two"
    },
    {
      "op": "+",
      "line": "2"
    }
  ]
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is text_diff, and the first 25 successful calls are free:

https://tools.funwords.eu/mcp

Questions

Is it word-level?

No, line by line.

How do I pay?

Each successful call costs $0.01; failed calls are not charged. The first 25 calls are free. Then pay with card credits (from $1; the key goes in an Authorization header or, for clients that can only fetch a URL, as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.

Related tools