Content
# Diff Checker API
[](https://diff-checker.api.klymax402.com/mcp)
[](https://x402.org)
[](LICENSE)
Compare two texts line-by-line. Returns structured diff with additions, deletions, unchanged lines, and summary stats. Pay-per-call via [x402](https://x402.org) (USDC on Base L2) -- no API key, no signup, no rate-limit wall.
Part of the [klymax402](https://klymax402.com) marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.
## Quickstart -- MCP
Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):
```json
{
"mcpServers": {
"diff-checker": {
"url": "https://diff-checker.api.klymax402.com/mcp"
}
}
}
```
## Quickstart -- HTTP (x402)
```bash
curl -X POST "https://diff-checker.api.klymax402.com/api/diff" \
-H "Content-Type: application/json" \
-d '{"text1":"...","text2":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body
```
Any x402-aware client ([`@x402/fetch`](https://www.npmjs.com/package/@x402/fetch), [`x402-agent-tools`](https://www.npmjs.com/package/x402-agent-tools), ATXP) handles the 402 -> sign -> retry cycle automatically.
## Tools
| Tool | Method | Path | Price | Description |
|---|---|---|---|---|
| `text_compare_diff` | POST | `/api/diff` | $0.005 | Compare two texts and show line-by-line differences |
### `text_compare_diff`
Use this when you need to compare two pieces of text and identify exactly what changed between them. Returns a structured line-by-line diff with summary statistics.
**Parameters**
| Name | Type | Required | Description |
|---|---|---|---|
| `text1` | string | yes | The original text (base) |
| `text2` | string | yes | The modified text to compare against |
Example response:
```json
{"changes":[{"type":"unchanged","content":"line 1"},{"type":"removed","content":"old line 2"},{"type":"added","content":"new line 2"}],"linesAdded":1,"linesRemoved":1,"linesUnchanged":1,"similarity":66.7}
```
**When to use**: code review (comparing before/after), tracking document revisions, verifying config file changes, or auditing template modifications. Use this BEFORE deploying config changes to understand what differs.
**Not for**: text classification (use `text_classify_content`), sentiment analysis (use `text_analyze_sentiment`), word counting (use `text_count_words`).
## Example agent prompts
- "Compare two pieces of text and identify exactly what changed between them"
## Payment
- Protocol: [x402](https://x402.org) -- HTTP-native pay-per-call, no signup, no API key
- Network: Base L2 (`eip155:8453`)
- Asset: USDC
- Facilitator: Coinbase CDP (primary), PayAI (fallback)
- Also reachable via [ATXP](https://atxp.ai) (OAuth-wrapped x402, RFC 9728 protected-resource metadata)
## Part of klymax402
100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.
- Catalog: https://klymax402.com/llms.txt
- Full API reference: https://klymax402.com/llms-full.txt
- Live stats: https://klymax402.com/stats
## License
MIT
