BaaS for Startups: Supabase vs Firebase vs Bun vs AppWrite in 2026

# BaaS Comparison
platforms:
  - name: "Supabase"
    type: "Open-source"
    database: "PostgreSQL"
    auth: "Yes (built-in)"
    realtime: "Yes"
    storage: "Yes"
    edge_functions: "Yes (Deno)"
    pricing: "Generous free tier"
    
  - name: "Firebase"
    type: "Proprietary"
    database: "Firestore (NoSQL)"
    auth: "Yes (built-in)"
    realtime: "Yes"
    storage: "Yes"
    cloud_functions: "Yes (Node.js)"
    pricing: "Pay-as-you-go"
    
  - name: "AppWrite"
    type: "Open-source"
    database: "PostgreSQL + MongoDB"
    auth: "Yes (built-in)"
    realtime: "Yes"
    storage: "Yes"
    cloud_functions: "Yes (Node.js, Dart)"
    pricing: "Self-host free"
    
  - name: "Convex"
    type: "Proprietary"
    database: "PostgreSQL"
    auth: "Yes (built-in)"
    realtime: "Yes"
    storage: "Yes"
    functions: "Yes (TypeScript)"
    pricing: "Free tier available"

# Quick start with Supabase
npm install @supabase/supabase-js

# Or use Supabase CLI
npm install -g supabase
supabase init
supabase start

-- Supabase: PostgreSQL with superpowers

-- 1. Real-time subscriptions
create table public.messages (
  id bigint generated by default as identity primary key,
  content text,
  user_id uuid references auth.users,
  created_at timestamptz default now()
);

-- Enable real-time
alter publication supabase_realtime add table public.messages;

-- 2. Row Level Security (RLS)
create policy "Users can see own messages"
  on messages for select
  to authenticated
  using (auth.uid() = user_id);

-- 3. PostgreSQL functions
create or replace function get_user_messages()
returns setof messages as $$
  select * from messages
  where user_id = auth.uid();
$$ language sql security definer;

-- 4. Triggers
create or replace function handle_new_user()
returns trigger as $$
begin
  insert into public.profiles (id, email)
  values (new.id, new.email);
  return new;
end;
$$ language plpgsql security definer;

create trigger on_auth_user_created
  after insert on auth.users
  for each row execute procedure handle_new_user();

// supabase/functions/send-welcome-email/index.ts
import { serve } from 'https://deno.land/[email protected]/http/server.ts'
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2'

const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',
}

serve(async (req) => {
  if (req.method === 'OPTIONS') {
    return new Response('ok', { headers: corsHeaders })
  }

  try {
    const supabase = createClient(
      Deno.env.get('SUPABASE_URL')!,
      Deno.env.get('SUPABASE_ANON_KEY')!
    )

    const { user_id, email } = await req.json()

    // Send welcome email (integrate with Resend, SendGrid, etc.)
    console.log(`Sending welcome email to ${email}`)

    return new Response(
      JSON.stringify({ success: true }),
      { headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
    )
  } catch (error) {
    return new Response(JSON.stringify({ error: error.message }), {
      status: 500,
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
    })
  }
})

// Firebase: Great for mobile and real-time apps

// 1. Firestore (NoSQL)
import { initializeApp } from 'firebase/app'
import { getFirestore, collection, addDoc, onSnapshot } from 'firebase/firestore'

const db = getFirestore(app)

// Real-time listener
function setupChatListener(chatId) {
  const messagesRef = collection(db, 'chats', chatId, 'messages')
  
  onSnapshot(messagesRef, (snapshot) => {
    const messages = snapshot.docs.map(doc => ({
      id: doc.id,
      ...doc.data()
    }))
    updateUI(messages)
  })
}

// 2. Authentication
import { getAuth, signInWithEmailAndPassword } from 'firebase/auth'
const auth = getAuth(app)

// 3. Cloud Functions
// functions/index.js
const functions = require('firebase-functions')
exports.onUserSignup = functions.firestore
  .document('users/{userId}')
  .onCreate(async (snap, context) => {
    const user = snap.data()
    // Send welcome email, setup defaults, etc.
  })

# AppWrite: Great for data privacy
# Can self-host for free

# docker-compose.yml
version: '3.8'
services:
  appwrite:
    image: appwrite/appwrite:1.4.0
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - appwrite:/storage
    environment:
      - _APP_ENV=production
      - _APP_REDIS_DISPLAY=host.docker.internal
      - _APP_DB_HOST=host.docker.internal
      - _APP_DB_PORT=5432

// AppWrite SDK
import { Client, Account, Databases } from 'appwrite'

const client = new Client()
  .setEndpoint('https://cloud.appwrite.io/v1')
  .setProject('[PROJECT_ID]')

const account = new Account(client)
const databases = new Databases(client)

// Auth
account.createEmailSession('email', 'password')

// Database
databases.listDocuments('[DATABASE_ID]', '[COLLECTION_ID]')

# Monthly free tiers (2025)
supabase:
  free:
    database: "500MB"
    api_calls: "Unlimited"
    auth: "50K monthly active users"
    storage: "1GB"
    bandwidth: "5GB"
  pro: "$25/month"
    database: "8GB"
    api_calls: "Unlimited"
    
firebase:
  free:
    firestore: "1GB"
    storage: "1GB"
    auth: "Unlimited"
    hosting: "1GB"
  blaze: "Pay as you go"
    # First $25/month free credit
    
appwrite:
  cloud:
    free: "1 project, 5 team members"
    pro: "$15/month"
  self_hosted:
    free: "Unlimited (your infrastructure)"

# Estimated costs at 100K MAU
platform_costs:
  supabase:
    compute: "$50"
    database: "$25"
    storage: "$20"
    total: "~$95/month"
    
  firebase:
    firestore: "$50-100"
    storage: "$30"
    functions: "$20"
    total: "~$100-150/month"
    
  appwrite_cloud:
    base: "$15"
    extra_usage: "~$50"
    total: "~$65/month"