# With shell, you can just pass the correct header with each request
curl "api_endpoint_here"
  -H "x-api-key: cR4zy5EcUR34p1k3y"

url = "api_endpoint_here"
headers = {
  "x-api-key" : "cR4zy5EcUR34p1k3y"
}

curl -X POST 'https://api.duden.de/v1/spellcheck' \
-H 'x-api-key: cR4zy5EcUR34p1k3y' \
-H 'Content-Type: application/json' \
-d '{
   "text":"Ein Schif, in einer kleineren Form auch Boot genannt ist ein Wasserfahrzeuk, das nach dem archimedischen Prinzip schwimmt.",
   "dictionary":[
    "Wäl"
  ],
  "grantPermissions":[
    "access filler words", 
    "access overlong sentences", 
    "access synonyms", 
    "access unfavorable phrases", 
    "access word frequency", 
    "access punctuation correction" 
  ]
}'

import requests
import json

url = "https://api.duden.de/v1/spellcheck"
headers = {
  "x-api-key" : "cR4zy5EcUR34p1k3y",
  "Content-Type" : "application/json"
}

permissions = [
  "access filler words",
  "access synonyms",
  "access punctuation correction"
]

dictionary = [
  "Delphin"
]

text = "Ein Schif, in einer kleineren Form auch Boot genannt ist ein Wasserfahrzeuk, das nach dem archimedischen Prinzip schwimmt."

r = requests.post(url=url, headers=headers, json={
  'text': text,
  'dictionary': dictionary,
  'grantPermissions': permissions
})

print(json.dumps(r.json(), indent=2))

{
  "data": {
    "spellAdvices": [
      {
        "errorCode": "21",
        "errorMessage": "Diese Schreibweise ist unbekannt. Bitte überprüfen Sie die Rechtschreibung dieses Wortes.",
        "shortMessage": "Dieses Wort korrigieren?",
        "label": "",
        "labelInline": "",
        "length": 5,
        "offset": 4,
        "originalError": "Schif",
        "proposals": [
          "Schi",
          "Schaf",
          "Schia",
          "Schief",
          "Schiff",
          "Schilf",
          "Schof"
        ],
        "synonyms": [],
        "occurrences": [
          {
            "offset": 4,
            "text": "Schif",
            "synonyms": []
          }
        ],
        "occurrenceIndex": 0,
        "type": "orth"
      },
      {
        "errorCode": "901",
        "errorMessage": "Bitte prüfen Sie, ob ein Komma eingefügt werden muss.",
        "shortMessage": "Hier ein Komma einfügen?",
        "label": "Komma einfügen?",
        "labelInline": "Komma einfügen?",
        "length": 11,
        "offset": 45,
        "originalError": "genannt ist",
        "proposals": [
          "genannt, ist"
        ],
        "synonyms": [],
        "occurrences": [],
        "occurrenceIndex": 0,
        "type": "comma insertion KI with >=0.8 and KI output"
      },
      {
        "errorCode": "21",
        "errorMessage": "Diese Schreibweise ist unbekannt. Bitte überprüfen Sie die Rechtschreibung dieses Wortes.",
        "shortMessage": "Dieses Wort korrigieren?",
        "label": "",
        "labelInline": "",
        "length": 14,
        "offset": 61,
        "originalError": "Wasserfahrzeuk",
        "proposals": [
          "Wasserfahrzeug"
        ],
        "synonyms": [
          {
            "synonyms": [
              "Fahrzeug"
            ],
            "description": "Fahrzeug",
            "originalWord": "Wasserfahrzeug",
            "id": 20144
          }
        ],
        "occurrences": [
          {
            "offset": 61,
            "text": "Wasserfahrzeuk",
            "synonyms": [
              {
                "synonyms": [
                  "Fahrzeug"
                ],
                "description": "Fahrzeug",
                "originalWord": "Wasserfahrzeug",
                "id": 20144
              }
            ]
          }
        ],
        "occurrenceIndex": 0,
        "type": "orth"
      }
    ],
    "styleAdvices": []
  }
}

curl -X POST 'https://api.duden.de/v1/synonyms' \
-H 'x-api-key: cR4zy5EcUR34p1k3y' \
-H 'Content-Type: application/json' \
-d '{
   "word":"Gelegenheit"
}'

import requests

url = "https://api.duden.de/v1/synonyms"
headers = {
  "x-api-key" : "cR4zy5EcUR34p1k3y",
  "Content-Type" : "application/json"
}
response = requests.request("POST", url, headers=headers, json={
  "word": "Gelegenheit"
})
print(response.text)

[
    {
        "id": 20216,
        "synonyms": [
            "Anlass",
            "Augenblick",
            "Chance",
            "Kairos",
            "Möglichkeit",
            "Okkasion",
            "Umstand",
            "günstiger Augenblick",
            "günstiger Moment",
            "günstiger Umstand",
            "günstiger Zeitpunkt"
        ],
        "description": "[günstiger] Moment",
        "originalWord": "Gelegenheit"
    },
    {
        "id": 68441,
        "synonyms": [
            "Angebot",
            "Ausverkauf",
            "Okkasion",
            "Rabattaktion",
            "Räumungsverkauf",
            "Schnäppchen",
            "Sonderaktion",
            "Sonderangebot",
            "Sonderposten",
            "reduzierte Ware"
        ],
        "description": "Sonderangebot",
        "originalWord": "Gelegenheit"
    },
    {
        "id": 79234,
        "synonyms": [
            "Anlass",
            "Ereignis",
            "Lage",
            "Sachverhalt",
            "Situation"
        ],
        "description": "Ereignis",
        "originalWord": "Gelegenheit"
    },
    {
        "id": 111211,
        "synonyms": [
            "Raum"
        ],
        "description": "Raum",
        "originalWord": "Gelegenheit"
    },
    {
        "id": 111216,
        "synonyms": [
            "Chance"
        ],
        "description": "Chance",
        "originalWord": "Gelegenheit"
    }
]

curl -X POST 'https://api.duden.de/v2/correction' \
-H 'x-api-key: cR4zy5EcUR34p1k3y' \
-H 'Content-Type: application/json' \
-d '{
   "promptId": "3f1c2a9e-0000-0000-0000-000000000000",
   "text": "Mein Test mid shreibfehler",
   "language": "german_DE",
   "outputType": "full",
   "callbackUrl": "https://example.com/callback"
}'

import requests

url = "https://api.duden.de/v2/correction"
headers = {
  "x-api-key" : "cR4zy5EcUR34p1k3y",
  "Content-Type" : "application/json"
}

r = requests.post(url=url, headers=headers, json={
  "promptId": "3f1c2a9e-0000-0000-0000-000000000000",
  "text": "Mein Test mid shreibfehler",
  "language": "german_DE",
  "outputType": "full",
  "callbackUrl": "https://example.com/callback"
})

print(r.json()["correlationId"])

{
  "correlationId": "0b7c6a52-4f3e-4d1a-9c55-2a8e1f0d7b3e"
}

{
  "requestType": "api",
  "correlationId": "0b7c6a52-4f3e-4d1a-9c55-2a8e1f0d7b3e",
  "feature": "correction",
  "language": "german_DE",
  "outputType": "full",
  "callbackUrl": "https://example.com/callback",
  "originalText": "Mein Test mid shreibfehler",
  "text": "Mein Test mit Schreibfehler",
  "diff": "@@ -11,7 +11,8 @@\n m\n i\n-d\n+t\n  \n-s\n+S\n+c\n h\n r",
  "isFinal": true
}

{
  "requestType": "api",
  "correlationId": "0b7c6a52-4f3e-4d1a-9c55-2a8e1f0d7b3e",
  "feature": "correction",
  "language": "german_DE",
  "outputType": "segment",
  "callbackUrl": "https://example.com/callback",
  "originalText": "Ein Schif ist ein Wasserfahrzeuk.",
  "text": "Ein Schiff ist ein Wasserfahrzeug.",
  "diff": "@@ -7,4 +7,5 @@\n h\n i\n+f\n f\n  \n@@ -30,4 +31,4 @@\n e\n u\n-k\n+g\n .",
  "isFinal": false,
  "segmentId": 0
}

{
  "requestType": "api",
  "correlationId": "0b7c6a52-4f3e-4d1a-9c55-2a8e1f0d7b3e",
  "feature": "correction",
  "language": "german_DE",
  "outputType": "segment",
  "callbackUrl": "https://example.com/callback",
  "originalText": "Es schwimmt nach dem archimedischen Prinzip.",
  "text": "Es schwimmt nach dem archimedischen Prinzip.",
  "diff": "",
  "isFinal": true,
  "segmentId": 1
}

{
    "code": 157,
    "hits": [
        {
            "begin_char": 25,
            "end_char": 52,
            "proposals": [
                "Meer, um einen Wäl zu retten"
            ],
            "snippet": "Meer um einen Wäl zu retten"
        }
    ],
    "info": "comma insertion DPF with output",
    "type": "gram",
    "attributes": {
        "errorCode": "157",
    }
}