---
title: "Compare how confirmed person facts change reachable offers"
method: POST
path: "/v1/reachable-offers/compare"
tags: ["Primary - Decisions"]
---

# Compare how confirmed person facts change reachable offers

`POST /v1/reachable-offers/compare`

## Request

- Base URL: `https://api.rateapi.dev`
- URL: `https://api.rateapi.dev/v1/reachable-offers/compare`
- Auth: API key in header `X-API-Key`

Evaluates a baseline and candidate person against the same immutable full-fleet eligibility graph, exact product request, and union rate read. The response reports newly reachable, no-longer-reachable, preserved, membership-path changes, and best-offer movement without treating unknown as rejection. Both profiles and all resulting paths are private and returned with `Cache-Control: no-store`.

**Authentication required**: Pass your API key in the `X-API-Key` header.

## Request body

- object
  - `baseline_person` Person, required (unresolved $ref)
  - `candidate_person` Person, required (unresolved $ref)
  - `product` Product, required (unresolved $ref)
  - `limit` integer: Visible rows per comparison bucket after both profiles have been evaluated against the full shared graph snapshot.

## Response `200`

Snapshot-consistent before/after comparison with source-backed offers and publication identities.

- object
  - `product` Product, required (unresolved $ref)
  - `baseline` object, required: Bounded baseline reachable-offers summary.
  - `candidate` object, required: Bounded candidate reachable-offers summary.
  - `deltas` object, required: Stable-institution before/after changes; source evidence remains on each underlying offer.
  - `snapshot` object, required: Shared graph/rate-read boundaries and publication identities used for the comparison.
  - `semantics` string, required: Positive-evidence comparison semantics, including that unknown is never ineligible.
  - `disclosure` string, required: Required explanation of what changed reachability does and does not prove.

## Other responses

- `400`: The request was malformed — a missing required field, an unparseable body, or a parameter outside its allowed range. The `error` field names what was wrong; retrying the identical request will fail identically.
- `401`: No API key, or a key that is unknown or disabled. Send it in the `X-API-Key` header. Free keys are issued instantly by POST /keys with an email address. The response carries `WWW-Authenticate` pointing at this host's protected-resource metadata, and the `RateLimit-*` headers describing the Free-tier budget a key issued now would carry (scope `anonymous`) — a rejected request spends none of it, so `Remaining` equals `Limit`.
- `402`: The key is valid, but RateAPI Routes is available only on Enterprise. The response includes `required_plan`, `upgrade_url`, and a `Link` header with `rel="upgrade"`; the rejected request does not consume quota.
- `429`: Quota exhausted for the current window. `Retry-After` gives the seconds to wait; `upgradeInfo` explains how to lift the cap. Retrying before the reset will fail again and still counts as a request.
- `503`: A required serving dependency is temporarily unavailable. This is not a negative eligibility or product decision; retry with backoff or continue using confirmed direct fields on deterministic endpoints.

---

[API](https://skmtc.dev/rateapi/apis/rate-api.md) · [All operations](https://skmtc.dev/rateapi/apis/rate-api/llms.txt) · [OpenAPI document](https://skmtc.dev/rateapi/apis/rate-api/revisions/06a6db76995f?raw)