---
title: "Forward a request to a PSP, substituting vaulted card data"
method: PUT
path: "/{proxyPath}"
tags: ["Primer Proxy API"]
---

# Forward a request to a PSP, substituting vaulted card data

`PUT /{proxyPath}`

## Request

- Base URL: `https://proxy.primer.io`
- URL: `https://proxy.primer.io/{proxyPath}`
- Auth: API key in header `X-Primer-Api-Key`

Forwards the request to the host named in `X-Target-Host`, at the given path,
substituting any card placeholders in the body first.

Any additional headers on the request, including the merchant's own PSP
credential (for example `Authorization`), are passed through unchanged.
`X-Primer-Api-Key` authenticates you against Primer.

A placeholder has the form `{{<token>.<FIELD>}}`, for example
`{{tok_abc.CARD_NUMBER}}`, and is substituted anywhere in the body.
A placeholder left unresolved fails the request rather than being forwarded.

The response is the target PSP's response, relayed byte-for-byte,
unless the `X-Primer-Proxy-Error` response header is present, in which
case Primer itself raised a fault before or after reaching the PSP.
See the `default` response below for both cases. The proxy never
retries a request to the PSP.

## Request body

- unknown

## Response `default`

The target PSP's response, relayed unchanged, unless `X-Primer-Proxy-Error` is present on the response, in which case the body is a Primer-raised problem document instead (`application/problem+json`).
Known Primer fault statuses: `400 invalid_request`, `401 unauthorized`, `403 vault_not_enabled`, `403 destination_not_allowed`, `404 token_not_found`, `405 method_not_allowed`, `409 token_consumed`, `410 token_expired`, `413 payload_too_large`, `415 unsupported_content_encoding`, `422 unresolved_placeholder` / `unknown_field` / `field_not_available` / `card_data_in_request`, `502 psp_unreachable`, `503 vault_unavailable`, `504 psp_timeout`. Any other status is the PSP's own.

- unknown

## Changes

- **2026-11-03** `75317247bfff`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/primer/apis/primer-api/changes/:proxyPath/put.md)

---

[API](https://skmtc.dev/primer/apis/primer-api.md) - [All operations](https://skmtc.dev/primer/apis/primer-api/llms.txt) - [OpenAPI document](https://skmtc.dev/primer/apis/primer-api/revisions/75317247bfff?raw)