# Create a redirect from a retired URL

`POST /api/v1/redirects`

## Headers

- `Idempotency-Key` (string, required) — A unique key per logical write. Replaying a request with the same key returns the first response byte for byte instead of applying the write twice.

## Request body

Required.

- `from_path` (string, required) — Required. The old URL this store must keep answering. NORMALIZED BEFORE IT IS STORED and before the uniqueness check: any scheme, host, QUERY STRING and fragment are dropped, a leading slash is forced and a trailing slash is trimmed except at the root, so "https://old.example/legacy/" and "legacy" both store as "/legacy". Matching is on the path alone, so two sources differing only in their query string are the SAME row and the second one is a 409 rather than a second redirect. The 2048 cap is measured in bytes, not characters, against the value you send.
- `to_path` (string, required) — Required. Where that URL now answers. TWO TARGET FORMS ARE ACCEPTED and one is refused, and the difference is an open-redirect one this table has a history with. Accepted: a store-relative path, which is normalized exactly like from_path, so "new-page" stores as "/new-page"; and an absolute http:// or https:// URL, which is stored VERBATIM on ANY host, deliberately, because retiring a page to another domain is a real merchant case. Refused with 400 invalid_redirect: a value beginning "//" or "/\", the protocol-relative form, which targets another host while looking like a path, so a consumer checking for an "http" prefix cannot tell it apart from a store-relative target. That form is the one thing this route refuses that the dashboard still accepts, so a row carrying it can exist from another writer even though no call here can create one. A value carrying any other scheme (javascript:, data:, mailto:) is NOT treated as an external target: it fails the http(s) test, takes a leading slash and is stored as an ordinary path. from_path and to_path must differ AFTER normalization, since a redirect pointing at its own source is a loop.
- `status_code` (301 | 302) — Optional, defaults to 301, which is the right default for the migration this family exists to serve: 301 consolidates ranking signals onto the target and 302 deliberately does not. STRICT HERE, unlike the dashboard, which collapses anything that is not an explicit 302 into 301. 307 and 308, both real redirect statuses another platform may have exported, are a 400 naming the two allowed values rather than a 201 describing a 301 the caller never asked for and could not notice.

## Responses

- `201` — Created
- `400` — The request was refused before any state changed. `code` is one of:

`invalid_body`, a write body this route will not take. `reason` partitions it
and `field` names the key when one key is at fault.
`invalid_query`, a query parameter, including limit and after.
`invalid_text`, a NUL byte or bytes that are not valid UTF-8 anywhere in the
path, the query or the body. Strip control characters before sending.
`idempotency_key_required`, a write sent without the Idempotency-Key header.
`invalid_request`, an Idempotency-Key longer than 255 bytes.

Routes add their own codes for rules only they know. Switch with a default arm.
- `401` — No credential, or one this API does not accept. `code` is always
`unauthorized`.

THE BODY IS DELIBERATELY UNINFORMATIVE. An expired key, a revoked key, a
publishable key, a key belonging to another merchant and a key that never
existed are all refused with the same bytes, so this response cannot be used to
probe which keys exist. Check the key's state in the dashboard rather than
inferring it here.

Send the key as `Authorization: Bearer <key>` or as `X-API-Key: <key>`. It is
never accepted in a query string.
- `403` — The key lacks the write_redirects scope. `code` is `insufficient_scope` and the message names the scope to ask the merchant for.
- `409` — The request is well formed and the store's current state refuses it.

EVERY WRITE CAN ANSWER TWO OF THESE, whatever it does:
`idempotency_key_reused`, this Idempotency-Key already served a different
method, path or body. The key namespace is per store and not per endpoint, so a
key built from a business id collides across routes; use a fresh key per
logical write.
`idempotency_key_in_progress`, an identical request is still running. Retry
after a short delay; exactly one of the racing calls will have applied.

`not_configured` means the merchant has not set something up yet, with
`resource` naming what. The remaining codes are the per-route state rules named
on the operation.
- `413` — The request body exceeded the cap named in the message. `code` is
`payload_too_large`. Nothing was read and nothing was recorded, so the same
Idempotency-Key may be reused once the body is smaller.
- `415` — The body was not declared as `application/json`. `code` is
`unsupported_media_type`.

This API reads ONE media type. The `+json` structured suffixes are refused
too, because they name semantics (merge-patch in particular) this API does
not implement, and reading such a body as plain JSON would be a silent
misreading. A write that carries NO body needs no Content-Type at all.
- `422` — An id INSIDE the request resolves to nothing on this store. `code` is
`unprocessable_reference`, `resource` names the kind of thing that did not
resolve and `field` names where it arrived, so the fix is mechanical.

Distinct from 404, which is about the url, and from 400, which is about the
bytes. The message stays generic about WHY the id did not resolve: an id owned
by another merchant must read identically to one that never existed.
- `429` — Too many requests. `code` is `rate_limited`.

Two limits apply independently: one on the credential and the route family,
one on the client address. The headers describe whichever has less left, so
honouring Retry-After always clears the window that bound.
- `default` — Any status this operation does not list, in the same envelope.

A 5xx means the request may or may not have applied. Retry it with the SAME
Idempotency-Key: that is the only way to find out without risking a duplicate,
and it is what the key is for.

A few 4xx conditions arrive here rather than as a listed status because they
depend on the merchant's plan or on a module being wired: 402 when a quota or a
plan limit is reached, and 503 when a capability the route needs is not
configured on this deployment. Both carry a `code` naming which.

## Example

```bash
curl --request POST \
  --url 'https://api.mercemur.com/api/v1/redirects' \
  --header 'Authorization: Bearer <token>'
```