When Paperless API Calls Work in curl, but Fail in n8n

While building an n8n workflow to fetch documents from my Paperless-ngx instance, I followed a typical approach:

  1. Opened the schema view over at /api/schema/view/ of my Paperless NGX instance.
  2. Authenticated and explored available endpoints like /api/documents/.
  3. After testing one endpoint via the web form, copied the generated curl command.
  4. Pasted that curl command into an n8n HTTP Request node, thinking it should work the same.

It didn’t.

Then I copied the same curl command into a Linux terminal — and it worked perfectly fine.

The Symptom: Login Page Instead of JSON

I was calling this endpoint:

https://paperless.example.com/api/documents/

But instead of the expected JSON response, the n8n node returned an HTML login page. Even though I included the correct token like this:

Authorization: Token YOUR_TOKEN

The result was something like:

[
  {
    "form": {
      "fields": {
        "login": { ... },
        "password": { ... }
      }
    },
    "html": "<!DOCTYPE html><html>...<form>Sign in</form></html>"
  }
]

Clearly not the /documents/ data I was expecting.

curl Worked Just Fine

Here’s the exact curl command that worked:

curl -X GET 'https://paperless.example.com/api/documents/' \
  -H 'Accept: application/json' \
  -H 'Authorization: Token YOUR_TOKEN'

That immediately returned the proper JSON document list.

So the credentials were fine. The endpoint was fine. But something about n8n’s request was causing a redirect to the login page.

Why It Happens: Django REST Framework Content Negotiation

Paperless-ngx is built on Django REST Framework (DRF), which tries to “guess” what format you want based on:

  • The Accept header
  • The URL (presence of ?format=)
  • The User-Agent

n8n uses Axios under the hood, which sends a verbose Accept header like this:

Accept: application/json,text/html,application/xhtml+xml,...

DRF sees that and thinks:

“Hmm, maybe this is a browser… better send HTML.”

So it serves the login page instead of JSON.

The Fix: Add ?format=json to the URL

Instead of:

https://paperless.example.com/api/documents/

Use:

https://paperless.example.com/api/documents/?format=json

This explicitly tells DRF to respond with JSON, skipping its content negotiation logic.

Once I made that change in n8n, everything worked instantly — same token, same headers.

Final Working Setup in n8n

In your HTTP Request node:

  • Method: GET
  • URL: https://paperless.example.com/api/documents/?format=json
  • Authentication: None
  • Headers:
{
  "Authorization": "Token YOUR_TOKEN",
  "Accept": "application/json"
}

No special User-Agent needed if ?format=json is in the URL.

Takeaway

If you’re building a workflow in n8n and your Paperless API request redirects to the login page — even with a valid token — the problem isn’t your credentials.

It’s Django REST Framework making assumptions about your request format.

Just add ?format=json to the URL to bypass the guesswork and get the response you expect.