# Forest Web: OpenAPI Breaking Change Detector

> Forest Web: OpenAPI Breaking Change Detector is a paid API for AI agents from http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-12).

Compares two public OpenAPI/Swagger contracts (before and after URLs) to detect directly observable breaking compatibility changes such as removed operations, newly required fields, narrowed enums, removed content types, and tightened authentication.

## Facts

- Endpoint: POST https://http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/openapi/breaking-change?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/forest-web-openapi-breaking-change-detector-1b2ce218
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_R86nJobMzmRoO03WpcBjE

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 forest-web-openapi-breaking-change-detector-1b2ce218 -d '<json body>'
```

Example prompt: Can you check whether the API update between https://api.example.com/v1/openapi.json (the old spec) and https://api.example.com/v2/openapi.json (the new spec) introduces any breaking changes for existing clients?

## When to prefer this

Choose this endpoint when you need a fast, deterministic, read-only check for breaking changes between two publicly accessible OpenAPI or Swagger contract versions — especially in CI/CD pipelines, pre-deployment gates, or dependency upgrade workflows. It is ideal when you need to check specific observable breaking change categories (removed operations, newly required fields, narrowed enums, removed response types, tightened auth) without executing any actual API calls. Prefer this over manual diffs or general-purpose LLM analysis when you want structured, reliable detection of contract-level breaking changes at low cost.

## Known failure modes

- Unreachable or invalid URL for before_url or after_url returns an error
- Non-OpenAPI/Swagger documents at the provided URLs result in a parse failure
- Compatibility changes that are not directly observable in the contract (e.g. semantic behavior changes) are reported as unknown rather than detected
- Private or auth-protected spec URLs cannot be fetched and will fail
- Malformed JSON/YAML in the spec files causes a parsing error

## How this service works

Compare two public OpenAPI or Swagger contracts and determine whether the API update contains directly observable breaking compatibility changes. Detects removed operations, newly required request inputs, narrowed inline enums, removed content types or successful responses and tightened authentication; unsupported compatibility questions remain unknown. No API operation is executed. Base mainnet USDC

## Output

A structured report indicating whether breaking compatibility changes were detected between the two OpenAPI/Swagger contracts. Results include specific categories of breaking changes found: removed operations, newly required request inputs, narrowed inline enums, removed content types or successful responses, and tightened authentication requirements. Unsupported compatibility questions are reported as unknown rather than false negatives.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "after_url": {
   "type": "string",
   "pattern": "^https?://",
   "maxLength": 2048,
   "minLength": 1,
   "description": "Public after url value used to scope this lookup."
  },
  "before_url": {
   "type": "string",
   "pattern": "^https?://",
   "maxLength": 2048,
   "minLength": 1,
   "description": "Public before url value used to scope this lookup."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/forest-web-openapi-breaking-change-detector-1b2ce218/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run](https://www.zero.xyz/host/http--forest-gas-station-mainnet--lcjl27p8lmjs.code.run/llms.txt)