Supabase Has a Free API: Here's How to Use It for Backend Automation

#supabase #backend #api #database

Supabase gives you a complete backend — database, authentication, storage, and real-time subscriptions — with auto-generated REST and GraphQL APIs. The free tier includes 500MB database, 1GB storage, and 50K monthly active users.

Why Use Supabase?

Instant API from your PostgreSQL database
Auth with email, OAuth, magic links — built in
Real-time subscriptions via WebSockets
Storage for files with CDN delivery
Free tier generous enough for production MVPs

Getting Started

Get your project URL and API key from supabase.com > Project Settings > API:

export SUPABASE_URL="https://your-project.supabase.co"
export SUPABASE_KEY="your-anon-key"

# Query data
curl -s "$SUPABASE_URL/rest/v1/products?select=*&limit=5" \
  -H "apikey: $SUPABASE_KEY" \
  -H "Authorization: Bearer $SUPABASE_KEY" | jq .

# Insert data
curl -s "$SUPABASE_URL/rest/v1/products" \
  -H "apikey: $SUPABASE_KEY" \
  -H "Authorization: Bearer $SUPABASE_KEY" \
  -H "Content-Type: application/json" \
  -H "Prefer: return=representation" \
  -d '{"name": "Widget Pro", "price": 29.99, "category": "tools"}' | jq .

Python Client

from supabase import create_client

supabase = create_client('https://your-project.supabase.co', 'your-anon-key')

# Query with filters
result = supabase.table('products').select('*').eq('category', 'electronics').lt('price', 100).order('price').limit(10).execute()

for product in result.data:
    print(f"{product['name']:30s} ${product['price']:.2f}")

# Insert
new = supabase.table('products').insert({'name': 'Gadget X', 'price': 49.99, 'category': 'electronics'}).execute()
print(f"Created: {new.data[0]['id']}")

# Update
supabase.table('products').update({'price': 39.99}).eq('id', 1).execute()

# Delete
supabase.table('products').delete().eq('id', 1).execute()

Authentication

# Sign up
result = supabase.auth.sign_up({'email': 'user@example.com', 'password': 'secure-password'})
print(f"User ID: {result.user.id}")

# Sign in
result = supabase.auth.sign_in_with_password({'email': 'user@example.com', 'password': 'secure-password'})
token = result.session.access_token
print(f"Token: {token[:20]}...")

# OAuth
result = supabase.auth.sign_in_with_oauth({'provider': 'github'})
print(f"Redirect URL: {result.url}")

File Storage

# Upload a file
with open('report.pdf', 'rb') as f:
    supabase.storage.from_('documents').upload('reports/q1-2026.pdf', f)

# Get public URL
url = supabase.storage.from_('documents').get_public_url('reports/q1-2026.pdf')
print(f"Public URL: {url}")

# List files
files = supabase.storage.from_('documents').list('reports/')
for file in files:
    print(f"{file['name']:30s} {file['metadata']['size']:>10d} bytes")

# Generate signed URL (temporary access)
signed = supabase.storage.from_('documents').create_signed_url('reports/q1-2026.pdf', 3600)
print(f"Signed URL (1 hour): {signed['signedURL']}")

Real-Time Subscriptions

def handle_change(payload):
    event = payload['eventType']
    record = payload.get('new', payload.get('old', {}))
    print(f"[{event}] {record}")

# Subscribe to table changes
supabase.table('orders').on('*', handle_change).subscribe()

# Subscribe to specific events
supabase.table('orders').on('INSERT', lambda p: print(f"New order: {p['new']}")).subscribe()
supabase.table('orders').on('UPDATE', lambda p: print(f"Order updated: {p['new']}")).subscribe()

Edge Functions

# Deploy an Edge Function
supabase functions deploy hello-world

# Call it
curl -s "$SUPABASE_URL/functions/v1/hello-world" \
  -H "Authorization: Bearer $SUPABASE_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name": "World"}'

// supabase/functions/hello-world/index.ts
Deno.serve(async (req) => {
  const { name } = await req.json();
  return new Response(JSON.stringify({ message: `Hello, ${name}!` }), {
    headers: { 'Content-Type': 'application/json' }
  });
});

Row-Level Security

-- Users can only see their own data
ALTER TABLE orders ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users see own orders" ON orders
  FOR SELECT USING (auth.uid() = user_id);

CREATE POLICY "Users create own orders" ON orders
  FOR INSERT WITH CHECK (auth.uid() = user_id);

Full-Stack App in 50 Lines

from supabase import create_client
from flask import Flask, request, jsonify

app = Flask(__name__)
db = create_client('https://your-project.supabase.co', 'your-service-key')

@app.route('/api/products', methods=['GET'])
def list_products():
    category = request.args.get('category')
    query = db.table('products').select('*')
    if category:
        query = query.eq('category', category)
    result = query.order('created_at', desc=True).limit(50).execute()
    return jsonify(result.data)

@app.route('/api/products', methods=['POST'])
def create_product():
    result = db.table('products').insert(request.json).execute()
    return jsonify(result.data[0]), 201

@app.route('/api/products/<int:id>', methods=['PUT'])
def update_product(id):
    result = db.table('products').update(request.json).eq('id', id).execute()
    return jsonify(result.data[0])

@app.route('/api/products/<int:id>', methods=['DELETE'])
def delete_product(id):
    db.table('products').delete().eq('id', id).execute()
    return '', 204

if __name__ == '__main__':
    app.run(port=5000)

Real-World Use Case

A two-person startup built a complete SaaS product using Supabase as their entire backend. Database, auth, file storage, real-time chat — all powered by Supabase APIs. They went from idea to paying customers in 3 weeks, with $0 infrastructure costs on the free tier. When they scaled to 10K users, they upgraded to the $25/month plan.