API documentation

1. Log in and go to “Integraties” → “API-sleutels” (Integrations → API keys). You need the “Integraties” (Integrations) team permission for this.
2. Create a key with a name, the scopes your integration needs and a validity period. Copy the key straight away: you will only see it once.
3. Put the key in an environment variable and retrieve your brochures:

curl https://slimfolderen.nl/api/v1/brochures?status=active \
  -H "Authorization: Bearer $SLIMFOLDEREN_API_KEY" \
  -H "Accept: application/json"

Base URL: https://slimfolderen.nl/api/v1. Send Accept: application/json with every request, so that errors are returned as JSON as well.

Send the key as a bearer token: Authorization: Bearer 12|Xh3k…. A key acts on behalf of the colleague who created it. Orders are placed in their name and follow their permissions. A key created by an administrator sees all of the company’s orders; keys of other roles see only their own orders.

A key can only call the endpoints it has a scope for:

Your credit balance, team, settings, other API keys and payments can never be reached with an API key, not even with all scopes. Choose a validity period for each key, from 30 days to one year, or let it never expire. Revoke a key as soon as you stop using it; the portal shows when each key was last used.

• GET/brochures

  Brochures, newest first. Filters: status, format, search.

  Scope: brochures:read

• GET/brochures/{id}

  A single brochure.

  Scope: brochures:read

• POST/orders/estimate

  Calculate the cost without sending anything.

  Scope: orders:create

• POST/orders

  Place one order (or a bulk order to one address).

  Scope: orders:create

• POST/orders/batch

  The same brochure to up to 100 recipients.

  Scope: orders:create

• GET/orders

  Orders, newest first. Filters: status, source, brochure_id, external_reference, date_from, date_to.

  Scope: orders:read

• GET/orders/{id}

  A single order with its status history.

  Scope: orders:read

• GET/campaigns

  Webhook campaigns. Filter: active.

  Scope: campaigns:read

• GET/campaigns/{id}

  A single campaign.

  Scope: campaigns:read

Lists are paginated: the items are in data, with current_page, last_page and total alongside. Use page and per_page (up to 100).

An order costs credits from your wallet: printing costs per page plus shipping costs per address. Calculate the cost first if you want to show or check it:

curl -X POST https://slimfolderen.nl/api/v1/orders/estimate \
  -H "Authorization: Bearer $SLIMFOLDEREN_API_KEY" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"brochure_id": "9d3c4a52-7f1e-4b8a-9c61-2f0e8b7a1d34", "recipient_country": "NL"}'

{
  "print_credits": 10,
  "shipping_credits": 12,
  "total_credits": 22,
  "paper": { "key": "normal", "label": "Standaard", "cover_gsm": 120, "inner_gsm": 100, "credits_per_page": 5 },
  "estimated_euro": 4.4
}

Then place the order. Only brochures with status active can be sent. The country defaults to NL.

curl -X POST https://slimfolderen.nl/api/v1/orders \
  -H "Authorization: Bearer $SLIMFOLDEREN_API_KEY" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: 6f1c2b8e-1d4a-4f0e-9b3a-2c7d5e8f9a10" \
  -d '{
    "brochure_id": "9d3c4a52-7f1e-4b8a-9c61-2f0e8b7a1d34",
    "recipient_name": "Jan Jansen",
    "recipient_company": "Jansen Installatietechniek B.V.",
    "recipient_address": "Keizersgracht 1",
    "recipient_postal_code": "1015 CJ",
    "recipient_city": "Amsterdam",
    "recipient_country": "NL",
    "external_reference": "crm-4711"
  }'

HTTP/1.1 201 Created

{
  "message": "Brochure succesvol ingepland voor verzending!",
  "order": {
    "id": "0b8f3f9e-2c4d-4e1a-8f57-6a9d2e1c7b40",
    "status": "queued",
    "quantity": 1,
    "total_credits": 22,
    "recipient_name": "Jan Jansen",
    "external_reference": "crm-4711",
    "brochure": "Productbrochure 2026",
    "created_at": "2026-10-27T09:15:02.000000Z"
  },
  "credit_balance": 978
}

With external_reference (up to 100 characters) you give the order your own reference, such as a CRM or order number. It comes back in every response and you can use it to look up orders. The Idempotency-Key makes it safe to resend the request after a time-out; see Retrying safely.

For multiple recipients, use POST /orders/batch with a list of recipients, each with its own external_reference if you like. Recipients at the same address go together in one envelope. The response is 201 if everything succeeded and 207 if some of it failed; those recipients are listed in failed, with their index and external_reference.

curl https://slimfolderen.nl/api/v1/orders/0b8f3f9e-2c4d-4e1a-8f57-6a9d2e1c7b40 \
  -H "Authorization: Bearer $SLIMFOLDEREN_API_KEY" \
  -H "Accept: application/json"

import { randomUUID } from 'node:crypto';

// One idempotency key per order. Store it and reuse the same key on every retry.
const idempotencyKey = randomUUID();

const response = await fetch('https://slimfolderen.nl/api/v1/orders', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.SLIMFOLDEREN_API_KEY}`,
    Accept: 'application/json',
    'Content-Type': 'application/json',
    'Idempotency-Key': idempotencyKey,
  },
  body: JSON.stringify({
    brochure_id: '9d3c4a52-7f1e-4b8a-9c61-2f0e8b7a1d34',
    recipient_name: 'Jan Jansen',
    recipient_address: 'Keizersgracht 1',
    recipient_postal_code: '1015 CJ',
    recipient_city: 'Amsterdam',
    external_reference: 'crm-4711',
  }),
});

const data = await response.json();
if (!response.ok) {
  // 422: data.errors per field, e.g. data.errors.credits when there is not enough credit
  throw new Error(data.message);
}
console.log(data.order.id, data.order.status);

A placed order is printed and costs credit. If you get no response, for example because of a time-out, you cannot tell whether the order has already been created. So send an Idempotency-Key with POST /orders and POST /orders/batch: a unique value of your own for each order or batch, such as a UUID. You can then safely retry with the same idempotency key and the same body.

• The same idempotency key with the same body returns the first response for 24 hours: the same status and body, with the header Idempotent-Replayed: true. No second order is created and nothing extra is charged. So for a batch that returned a 207, the recipients that succeeded are not sent again.
• Idempotency keys apply per API key. The same idempotency key with a different body or on a different endpoint returns a 422.
• If the first request is still running, you get a 409 with Retry-After. Wait that number of seconds and try again.
• A 4xx is not stored, because nothing was created. After topping up your credit or correcting a field, for example, you reuse the same idempotency key.
• A 5xx is stored, because a batch may already have been partly sent. A 409 without Retry-After means that the first request was aborted. In both cases, use external_reference to check what has been created, and send the rest with a new idempotency key.

HTTP/1.1 201 Created
Idempotent-Replayed: true

{ ...the same response as the first time... }

curl "https://slimfolderen.nl/api/v1/orders?external_reference=crm-4711" \
  -H "Authorization: Bearer $SLIMFOLDEREN_API_KEY" \
  -H "Accept: application/json"

Errors are returned as JSON with a message. With a 422, errors shows what is wrong with each field. The text of message and of the field errors is in Dutch; rely on the status code and field names in your code.

• 401No key, or an invalid, expired or revoked key.
• 403The key lacks the scope (see required_scopes), the endpoint is not available to API keys, or the owner of the key is not authorised to use it.
• 404Does not exist or does not belong to your company.
• 409A request with the same Idempotency-Key is still being processed or was aborted.
• 422Invalid input, a brochure that cannot be sent, insufficient credit (errors.credits) or an Idempotency-Key that has already been used for a different request (errors.idempotency_key).
• 429Rate limit reached. Wait the number of seconds given in the Retry-After header.

HTTP/1.1 403 Forbidden

{
  "message": "Deze API-sleutel mist de benodigde scope.",
  "required_scopes": ["orders:create"]
}

Each key can make 60 requests per minute. In addition, a single user can place up to 60 orders and 20 batches per minute. Every response includes X-RateLimit-Limit and X-RateLimit-Remaining. With a 429, Retry-After tells you after how many seconds you can try again.

All endpoints, fields and responses are described in the OpenAPI 3.1 specification. Import it into Postman, Insomnia or a code generator.

Prefer not to write code? With webhooks you can connect your CRM, Zapier or Make without any programming.