Text diff

Line-by-line diff of two texts (LCS). Returns unified-style ops and change counts. Up to 2000 lines per side.

Input

Field	Type	Description
a *	string	Original text
b *	string	New text

Example output

{
  "added": 1,
  "removed": 1,
  "unchanged": 1,
  "diff": [
    {
      "op": " ",
      "line": "line1"
    },
    {
      "op": "-",
      "line": "line2"
    },
    {
      "op": "+",
      "line": "line2 changed"
    }
  ]
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/text-diff \
  -H "Content-Type: application/json" \
  -d '{"a":"line1\nline2","b":"line1\nline2 changed"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/text-diff", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "a": "line1\nline2",
    "b": "line1\nline2 changed"
  }),
});

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