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Documentation Index

Fetch the complete documentation index at: https://casparser.in/docs/llms.txt

Use this file to discover all available pages before exploring further.

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API Keys

All CAS Parser API requests require authentication via the x-api-key header.

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Getting Your API Key

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From the dashboard

  1. Sign up at app.casparser.in
  2. Navigate to Developers → API Keys
  3. Click Generate API Key
  4. Copy and store securely

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From a coding agent (automated)

If you’re using a coding agent (Claude Code, Cursor, etc.), it can obtain an API key for you automatically. The agent generates a one-time URL, you open it in your browser and approve, and the agent receives the key — no copy-paste needed. 
# 1. Agent generates a random token
TOKEN=$(openssl rand -hex 32)

# 2. You open this URL and sign in
# https://app.casparser.in/agent-auth?token=${TOKEN}&client_name=YOUR_AGENT_NAME

# 3. Agent polls until you approve
curl -s https://api.casparser.in/v1/agent-auth/token/${TOKEN}
# → {"status": "approved", "api_key": "sk_...", "email": "..."}
See the API reference for full details on the agent auth endpoints.
Never expose your API key in client-side code. Use access tokens for frontend applications.

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Using API Keys

import requests

response = requests.post(
    "https://api.casparser.in/v4/smart/parse",
    headers={"x-api-key": "YOUR_API_KEY"},
    files={"file": open("cas.pdf", "rb")},
    data={"password": "ABCDE1234F"}
)

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Access Tokens

For frontend/SDK applications, use short-lived access tokens instead of exposing your API key.

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Token Flow

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Generate Access Token

Backend (server-side): 
import requests

response = requests.post(
    "https://api.casparser.in/v1/token",
    headers={"x-api-key": "YOUR_API_KEY"},
    json={"expiry_minutes": 30}
)

access_token = response.json()["access_token"]
# Returns: at_xxxxxxxxxxxxxxxxxx
Frontend (client-side): 
// Get token from your backend
const { access_token } = await fetch('/api/casparser/token').then(r => r.json());

// Use token in place of API key
const response = await fetch('https://api.casparser.in/v4/smart/parse', {
  method: 'POST',
  headers: { 'x-api-key': access_token },  // Use token here
  body: formData
});

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Token Properties

PropertyValue
Prefixat_
Max TTL60 minutes
ScopeAll /v4/* endpoints
RestrictionsCannot generate other tokens, cannot access billing

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Verify Token

response = requests.post(
    "https://api.casparser.in/v1/token/verify",
    headers={"x-api-key": "YOUR_API_KEY"},
    json={"access_token": "at_xxx"}
)

data = response.json()
# {"valid": true, "expires_at": "2024-01-15T11:30:00Z"}

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Security Best Practices

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1. Environment Variables

Never hardcode API keys: 
# ❌ Bad
API_KEY = "sk_live_abc123"

# ✅ Good
import os
API_KEY = os.environ.get("CASPARSER_API_KEY")

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2. Backend Token Generation

Create a backend endpoint: 
# Flask example
from flask import Flask, jsonify
import requests
import os

app = Flask(__name__)

@app.route('/api/casparser/token')
def get_token():
    response = requests.post(
        'https://api.casparser.in/v1/token',
        headers={'x-api-key': os.environ['CASPARSER_API_KEY']},
        json={'expiry_minutes': 30}
    )
    return jsonify(response.json())

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3. Rate Limiting

Implement rate limiting on your backend: 
from flask_limiter import Limiter

limiter = Limiter(app, default_limits=["60 per minute"])

@app.route('/api/parse')
@limiter.limit("10 per minute")
def parse_cas():
    # Your parsing logic
    pass

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4. HTTPS Only

Always use HTTPS for API requests. The API will reject HTTP requests.

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5. Key Rotation

Rotate API keys periodically:
  1. Generate new API key in dashboard
  2. Update environment variables
  3. Deploy updated code
  4. Delete old API key

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Sandbox Key

For testing and development: 
sandbox-with-json-responses
  • Returns sample data
  • No credit consumption
  • Rate limited to 10 requests/minute

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Troubleshooting

ErrorCauseSolution
401 UnauthorizedInvalid API keyCheck key in dashboard
401 UnauthorizedMissing headerAdd x-api-key header
403 ForbiddenExpired tokenGenerate new access token
403 ForbiddenQuota exceededCheck credits with /v1/credits

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Next Steps

Quickstart

Make your first API call

Error Handling

Handle authentication errors