API documentation

The CatéGPT API returns sourced answers about the Catholic faith. Ideal for integrating the assistant into an application, a back-office or a bot.

Base URL

https://categpt.chat

Authentication

The API authenticates with an API key (Bearer token).

1. Create an account at https://categpt.chat.
2. Open the Developer page of your account.
3. Generate an API key (cgpt_live_…). It is shown only once — copy it immediately.
4. Send it in the Authorization header.

Authorization: Bearer cgpt_live_yourKey

Credits & billing

Usage is prepaid: top up your account, then each answer is debited. The billed amount is the model cost times a multiplier (~2×). An answer is generated only if the balance is positive.

Endpoint — Generate an answer

POST /api/v1/answer
Content-Type: application/json
Authorization: Bearer cgpt_live_…

Parameters (JSON body)

Field	Type	Required	Description
question	string	yes	The question (1 to 4000 chars).
mode	string	no	quick (default) or academic.
level	string	no	child, teen, catechesis, general (default), academic, priest.
language	string	no	2-letter language code (fr, en…). Auto-detected otherwise.

Example request

curl -X POST https://categpt.chat/api/v1/answer \
  -H "Authorization: Bearer cgpt_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "question": "What does the Catechism say about the Eucharist?",
    "mode": "academic",
    "level": "general"
  }'

Response

{
  "answer": "…text with [1], [2] markers…",
  "references": [
    {
      "source_type": "catechism",
      "title": "Catechism of the Catholic Church",
      "citation": "CCC 1373-1377",
      "url": "https://www.vatican.va/…",
      "verified": true,
      "language": "en"
    }
  ],
  "usage": { "prompt_tokens": 1234, "completion_tokens": 567, "billed_usd": 0.012 },
  "language": "en"
}

Source types (source_type)

bible, catechism, council, pontifical, canon_law, social_doctrine, church_father, church_doctor, other.

Saint of the day API

GET /api/v1/saint — free, no key

Returns the feast and saint of the day from the liturgical calendar. This endpoint is free: no API key is required and CORS is open (callable directly from a browser).

Parameter	Type	Required	Description
date	string	no	Day as YYYY-MM-DD (default: today, UTC).
locale	string	no	fr (default), en, de, it, es, pt, pl.

curl "https://categpt.chat/api/v1/saint?locale=en"

{
  "date": "2026-08-11",
  "name": "Sainte Claire, vierge",
  "degree": "Mémoire",
  "color": "blanc",
  "description": "…Markdown description…",
  "excerpt": "…two-sentence summary…",
  "permalink": "https://app.categpt.chat/en/saint/august-11-sainte-claire-vierge",
  "readings": [ { "type": "lecture_1", "ref": "…", "titre": "…", "contenu": "…" } ],
  "offices": { "laudes": "…" },
  "zones": { "france": "…" }
}

description and excerpt come back in the requested locale (French fallback); readings holds the translated mass readings when locale ≠ fr; offices stays in French (official AELF text). Returns 404 (not_found) when no data exists for that day.

POST /api/v1/saint/ask — ask about the day’s feast

Same authentication (API key), same quotas and same billing as /api/v1/answer — but the question is first enriched with the day’s liturgical context (feast, colour, readings, description), like the chat on the “Saint of the day” page.

POST /api/v1/saint/ask
Content-Type: application/json
Authorization: Bearer cgpt_live_…

Field	Type	Required	Description
question	string	yes	The question (1 to 4000 chars).
date	string	no	Day YYYY-MM-DD (default: today, UTC).
locale	string	no	Answer language (fr, en…). Auto-detected otherwise.
mode	string	no	quick (default) or academic.
level	string	no	Same as /api/v1/answer.

curl -X POST https://categpt.chat/api/v1/saint/ask \
  -H "Authorization: Bearer cgpt_live_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "question": "Which saint is celebrated today, and why?",
    "locale": "en"
  }'

The response has the same format as /api/v1/answer (answer, references, usage, language), plus the date of the liturgical day that was used.

Examples

JavaScript (fetch)

const res = await fetch("https://categpt.chat/api/v1/answer", {
  method: "POST",
  headers: {
    "Authorization": "Bearer cgpt_live_xxx",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({ question: "Who was Saint Augustine?" }),
});
const data = await res.json();
console.log(data.answer, data.references);

Python (requests)

import requests

r = requests.post(
    "https://categpt.chat/api/v1/answer",
    headers={"Authorization": "Bearer cgpt_live_xxx"},
    json={"question": "Who was Saint Augustine?"},
)
data = r.json()
print(data["answer"])

Rate limits

Up to 60 requests per minute per key. Beyond that, the API returns 429.

Errors

HTTP code	error	Meaning
400	invalid_request	Malformed request.
401	invalid_api_key	Missing or invalid key.
402	insufficient_credits	Credit balance depleted.
429	rate_limited	Too many requests.
502	upstream_error	Upstream model error.

Errors are returned as { "error": { "code": "…" } }.

No-code integration

To add the chat to a website without coding, use the widget and plugins: see the widget documentation.