# Webhook transformers

> Reshape outgoing webhook events for a service that expects its own format, without a relay server.

Source: https://shopfa.st/docs/plugins/transformers

Attach a transformer to an endpoint in **Settings → Developers → Webhooks** (or `PATCH` the endpoint with
`transformerPluginId`). Each attempt runs `transform` before the event is signed:

```lua
function plugin.transform(ctx, input)
  local e = input.event
  if e.type ~= "order.paid" then return { drop = true } end
  local o = e.data.order
  return {
    body = { text = "New order " .. o.number .. " · " .. money.format(o.totalMinor, o.currency) },
    headers = { ["x-event-type"] = e.type },
  }
end
```

`input`: `event` (`id`, `type`, `createdAt`, `data`) and `endpoint` (`url`). Return one of:

- `{ body = … }`: a table is sent as JSON, a string as is (256 KB). Optional `headers`: lowercase `x-` names only, never
  `x-shopfast-*`; the Standard Webhooks headers are always ShopFast's.
- `{ drop = true }`: nothing is sent and the delivery is closed as done.

The body you return is what gets signed, with the endpoint's own secret, so receivers that verify keep working. A
transformer that fails counts as a failed attempt and is retried on the normal schedule; a transformer that is turned
off holds deliveries (they retry) rather than sending unshaped events by surprise. Transformers get no network access.