# PageDiff API

Pay-per-call web page content diffing for monitoring agents. Provide a URL and two dates to compare Wayback Machine snapshots and receive structured added, removed, and modified text blocks.

## When to use this API

Use PageDiff when you need to detect and summarize text changes between two historical versions of a public web page. It is best for competitor pricing changes, terms and privacy policy monitoring, documentation drift, product positioning changes, and compliance page audits.

Do not use PageDiff for live scraping, crawling many pages, JavaScript-rendered screenshots, or private/authenticated pages. PageDiff compares Internet Archive Wayback Machine snapshots, so results depend on archived snapshot availability.

## Base URL

https://pagediff-api.hahavoid0.workers.dev

## Authentication and payment

All paid endpoints require x402 payment. Unpaid requests return HTTP 402 Payment Required with standard x402 payment instructions in response headers.

- Network: Base mainnet, eip155:8453
- Asset: USDC, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913
- Facilitator: https://facilitator.x402.org
- x402 metadata: https://pagediff-api.hahavoid0.workers.dev/.well-known/x402.json
- OpenAPI schema: https://pagediff-api.hahavoid0.workers.dev/openapi.json
- Agent card: https://pagediff-api.hahavoid0.workers.dev/.well-known/agent-card.json
- MCP metadata: https://pagediff-api.hahavoid0.workers.dev/.well-known/mcp.json

## Endpoint: diff a web page between two archived dates

POST https://pagediff-api.hahavoid0.workers.dev/diff

Price: $0.050 per request (50000 atomic USDC units)

Use this endpoint when the user asks whether a page changed between two dates, what changed on a pricing page, how terms/privacy/docs changed over time, or needs structured added/removed/modified text from archived page versions.

Request body schema:

```json
{
  "type": "object",
  "required": [
    "url",
    "from",
    "to"
  ],
  "properties": {
    "url": {
      "type": "string",
      "examples": [
        "https://example.com/"
      ]
    },
    "from": {
      "type": "string",
      "description": "Requested earlier snapshot date in YYYY-MM-DD format.",
      "examples": [
        "2023-01-01"
      ]
    },
    "to": {
      "type": "string",
      "description": "Requested later snapshot date in YYYY-MM-DD format.",
      "examples": [
        "2024-01-01"
      ]
    }
  }
}
```

Request body fields:

- url: string, required. Absolute http or https URL to compare.
- from: string, required. Earlier requested snapshot date in YYYY-MM-DD format.
- to: string, required. Later requested snapshot date in YYYY-MM-DD format.

Example request:

```http
POST https://pagediff-api.hahavoid0.workers.dev/diff
Content-Type: application/json

{
  "url": "https://example.com/",
  "from": "2023-01-01",
  "to": "2024-01-01"
}
```

Example success response:

```json
{
  "url": "https://example.com/",
  "from_snapshot": {
    "requested_date": "2023-01-01",
    "timestamp": "20230101000000",
    "original_url": "https://example.com/",
    "archive_url": "https://web.archive.org/web/20230101000000id_/https://example.com/",
    "statuscode": "200",
    "mimetype": "text/html",
    "digest": "EXAMPLE"
  },
  "to_snapshot": {
    "requested_date": "2024-01-01",
    "timestamp": "20240101000000",
    "original_url": "https://example.com/",
    "archive_url": "https://web.archive.org/web/20240101000000id_/https://example.com/",
    "statuscode": "200",
    "mimetype": "text/html",
    "digest": "EXAMPLE2"
  },
  "summary": {
    "change_level": "low",
    "added_count": 1,
    "removed_count": 1,
    "modified_count": 0
  },
  "added": [
    "Updated example page content."
  ],
  "removed": [
    "Original example page content."
  ],
  "modified": []
}
```

Response notes:

- from_snapshot and to_snapshot describe the nearest usable Wayback snapshots found for the requested dates.
- summary.change_level is one of none, low, moderate, or high.
- added contains text blocks present in the later snapshot but not the earlier snapshot.
- removed contains text blocks present in the earlier snapshot but not the later snapshot.
- modified contains paired before/after text blocks when PageDiff detects a changed block.

Error behavior:

- 402: payment required. Retry with a valid x402 payment header.
- 400: invalid JSON, URL, or date input.
- 404: no usable Wayback snapshot found for one or both requested dates.
- 500: upstream Wayback or processing error. Failed requests do not settle payment.

## Agent workflow

1. If the task is about archived web page change detection, select POST https://pagediff-api.hahavoid0.workers.dev/diff.
2. Validate that the user supplied a public http or https URL and two YYYY-MM-DD dates.
3. If using AgentCash, run endpoint discovery or schema check before the first paid call:
   - npx agentcash@latest discover https://pagediff-api.hahavoid0.workers.dev
   - npx agentcash@latest check https://pagediff-api.hahavoid0.workers.dev/diff
4. Execute the paid request with the JSON body above.
5. Summarize the added, removed, and modified arrays for the user, and mention the exact snapshot timestamps used.

## Minimal AgentCash call

```bash
npx agentcash@latest fetch https://pagediff-api.hahavoid0.workers.dev/diff -m POST -b '{"url":"https://example.com/","from":"2023-01-01","to":"2024-01-01"}'
```