---
title: "What changed against the observation before it"
method: GET
path: "/v1/page-observations/{observationId}/comparison"
tags: ["PageObservations"]
---

# What changed against the observation before it

`GET /v1/page-observations/{observationId}/comparison`

## Request

- Base URL: `https://api.ironfang.com/audit`
- URL: `https://api.ironfang.com/audit/v1/page-observations/{observationId}/comparison`
- Auth: one of:
  - HTTP bearer
  - HTTP bearer

Computed from stored evidence under the audit's change policy - normalised text hunks (whitespace collapsed, numbers masked, ignored selectors removed), scores, URL/title/status changes, rule transitions and screenshot artifact ids for each side. The raw artifacts are untouched. A first capture has no previous side and says why.

## Path parameters

- `observationId` string, uuid, required

## Response `200`

Comparison

## Other responses

- `400`: Problem response
- `404`: Not found

---

[API](https://skmtc.dev/ironfang/apis/ironfang-audit-api.md) · [All operations](https://skmtc.dev/ironfang/apis/ironfang-audit-api/llms.txt) · [OpenAPI document](https://skmtc.dev/ironfang/apis/ironfang-audit-api/revisions/7430deff2cbd?raw)