Authentication

All RAIL API requests are authenticated with API keys. Keys are tied to your account, carry your credit balance, and appear in your usage logs.

Getting an API Key

Generate keys from the API Keys section of your dashboard. Keys start with rail_ and are shown once — copy them immediately.

Using the API Key

Pass your key as a Bearer token in the Authorization header on every request:

Authorization: Bearer YOUR_RAIL_API_KEY

Full curl example:

curl -X POST https://api.responsibleailabs.ai/railscore/v1/eval \
  -H "Authorization: Bearer YOUR_RAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"content": "Your AI-generated text here", "mode": "basic"}'

SDK Authentication

Both SDKs accept the API key at client construction and handle the header automatically:

from rail_score_sdk import RailScoreClient
import os

# Pass key directly (fine for scripts, not production web apps)
client = RailScoreClient(api_key="YOUR_RAIL_API_KEY")

# Recommended: read from environment variable
client = RailScoreClient(api_key=os.environ["RAIL_API_KEY"])

# The client attaches Authorization: Bearer <key> on every request

Environment Variables

Never hardcode API keys in source files. Use environment variables and keep keys out of version control.

# .env  (add to .gitignore — never commit this file)
RAIL_API_KEY=YOUR_RAIL_API_KEY

# Python
from dotenv import load_dotenv, find_dotenv
import os
load_dotenv(find_dotenv())
api_key = os.environ["RAIL_API_KEY"]

# Node.js
import 'dotenv/config';   // or require('dotenv').config()
const apiKey = process.env.RAIL_API_KEY;

# Add via Vercel dashboard → Settings → Environment Variables
# Variable name: RAIL_API_KEY
# Environment:   Production (and optionally Preview)

# In your code (server-side only — never NEXT_PUBLIC_)
const apiKey = process.env.RAIL_API_KEY;

# Pass at runtime — never bake secrets into image layers
docker run -e RAIL_API_KEY=YOUR_RAIL_API_KEY my-app

# docker-compose.yml
services:
  app:
    image: my-app
    environment:
      - RAIL_API_KEY=${RAIL_API_KEY}   # sourced from host env

# Or mount a secrets file
docker secret create rail_api_key ./rail_key.txt

Key Management

You can create multiple keys for different environments (production, staging, CI). Manage keys from your dashboard:

Rate Limits

Rate limits are applied per API key. Exceeding the limit returns HTTP 429.

Security Best Practices

Auth Error Responses

Next Steps