# Changelog State API – Change History for x402 Vendor

> Changelog State API – Change History for x402 Vendor is a paid API for AI agents from changelog-state-api.replit.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-24).

Returns detected changelog update history (new releases, version changes, date/title changes, breaking signals) for the tracked vendor 'x402'.

## Facts

- Endpoint: GET https://changelog-state-api.replit.app/api/monitors/x402/changes?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/changelog-state-api-change-history-for-x402-vendor-ee896f03
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Xojp7NO17psyapjrN-vPn

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability changelog-state-api-change-history-for-x402-vendor-ee896f03
```

Example prompt: Show me the detected changelog change history for x402 — include new releases and breaking signals from the last 30 days, up to 100 results.

## When to prefer this

Use this endpoint when you need the historical log of all detected changes for the x402 vendor specifically, including fine-grained change types like breaking signals, version changes, and title changes. Prefer this over the 'recent releases' sibling endpoint when you need the raw change event stream rather than structured release summaries, or when you need to filter by change type or time window.

## Known failure modes

- Invalid or unrecognized vendor slug returns empty results or 404
- 'since' timestamp in wrong format causes validation error
- limit out of range (below 1 or above 200) causes 400 error
- No changes found in specified window returns empty array
- Service unavailability returns 5xx error

## How this service works

Detected changelog update history for one tracked vendor.

## Output

A JSON array of changelog change records for the x402 vendor, each including the change type (e.g. new_release, version_changed, breaking_signal), detection timestamp, and relevant metadata such as version strings, titles, or dates. Supports filtering by change type and time window.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object",
     "required": [
      "slug"
     ],
     "properties": {
      "slug": {
       "type": "string",
       "example": "openai",
       "pattern": "^[a-z0-9][a-z0-9-]*$",
       "maxLength": 64,
       "minLength": 1,
       "description": "Vendor slug, lowercase alphanumeric with dashes. Take one from GET /api/monitors and substitute it into the path: `{slug}` is a placeholder that names no vendor and never returns data. Worked example: GET /api/monitors/openai."
      }
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "type": {
       "enum": [
        "new_release",
        "version_changed",
        "date_changed",
        "title_changed",
        "breaking_signal"
       ],
       "type": "string",
       "description": "Restrict to a single change type."
      },
      "limit": {
       "type": "integer",
       "default": 50,
       "maximum": 200,
       "minimum": 1,
       "description": "Maximum number of change rows to return."
      },
      "since": {
       "type": "string",
       "format": "date-time",
       "description": "Only return changes detected at or after this instant."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "enum": [
      "json"
     ],
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   },
   "description": "Detected changelog update history (paid)"
  }
 },
 "description": "Call shape for GET /api/monitors/{slug}/changes."
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/changelog-state-api-change-history-for-x402-vendor-ee896f03/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from changelog-state-api.replit.app](https://www.zero.xyz/host/changelog-state-api.replit.app/llms.txt)