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MongoDB Atlas vs Firebase vs Supabase

MongoDB Atlas, Firebase, Supabase side by side: price, free tier, who each one fits and when to skip it.
Item
MongoDB Atlas
Firebase
Supabase
What it doesManaged MongoDB, a document database, running on AWS, Google Cloud or Azure.Google's app platform: login, Firestore database, file storage and free push notifications (FCM).Postgres database with login, file storage, edge functions and realtime in one project.
Best forAn AI app that stores loose JSON like chat history and agent outputs, and wants vector search in the same database.A mobile-first app for a mostly Android audience that needs push notifications and login working within the week.A solo founder who wants login, database and uploads in one place, with a region close to their users so the app feels fast.
Skip it ifYour data is billing, plans and permissions that depend on joins and transactions across tables.Your SaaS runs on relational data like charges, plans and reports that you will want to query with SQL.You plan to leave a free project idle while you validate, since free projects get paused after a week without activity.
SetupNeeds a developer. A free cluster in about 10 minutes; the backend API around it takes a few days.Needs a developer. Login and push on a test app in a day; security rules and data modeling take most of a week.Needs a developer. Login and a first table in an afternoon; access rules and email setup take another day or two.
PriceFree; Flex from $8 up to $30/monthFree Spark plan, then pay-as-you-go (Blaze)Free, then Pro from $25/month plus usage
What it costs in practiceA SaaS with 2,000 monthly active users and 3 GB of data outgrows the free 512 MB and goes to Flex: $8/month at up to 100 operations per second, capped at $30/month at the 400 to 500 tier. Past 5 GB, a dedicated M10 starts at about $57/month (estimate).With 2,000 monthly users, login and push are free. If each user loads 200 documents a day, that's 400k reads a day, about 12 million a month. The free 50k a day covers about 1.5 million; the other 10.5 million at $0.03 per 100k (us-central1) cost about $3/month on Blaze (estimate; the price varies by region).A SaaS with 2,000 monthly active users and a 3 GB database outgrows the free 500 MB, so it goes to Pro: $25/month, which already covers one Micro server, 100k users, 8 GB of disk and 250 GB of egress. Add $10 for a custom domain on login and you're at about $35/month (estimate, in dollars).
Free planM0 cluster free forever with 512 MB of storage.Spark plan: 50k monthly users, 1 GiB Firestore with daily read/write limits, push at no cost.2 projects, 50k monthly users, 500 MB database and 1 GB of files; paused after a week idle.
Free tier512 MB (M0 cluster)Push free; 50k MAU; 1 GiB Firestore50k MAU, 500 MB DB, 1 GB files
First paid planFlex: $8 to $30/monthFree on Spark (50k MAU included)Free (Pro: $25/mo, 100k MAU included)
Database typeNoSQL documents (MongoDB)NoSQL documents (Firestore)Postgres
Open sourceNo: noNo: noYes: yes
Before you build
  • A free cluster with zero connections for 30 days is paused automatically, and you get only one free cluster per project.
  • The free cluster handles up to 100 operations per second and 512 MB, and some features like Performance Advisor and server-side JavaScript are off.
  • Flex stops at 5 GB with no automatic growth, takes one fixed snapshot a day and has no point-in-time restore; past that you move to a dedicated M10.
  • Atlas's built-in Data API, HTTPS endpoints, Device Sync and app hosting reached end of life on September 30, 2025, so old tutorials that skip the backend no longer work.
  • Since February 3, 2026, Cloud Storage requires the Blaze plan, even for the default bucket. On Spark, uploads and downloads fail until you add a card.
  • Budget alerts don't stop anything: they only send email. On Blaze, a loop of reads keeps being billed until you notice.
  • Firestore bills every document a query returns, and every change a live listener receives counts as a new read, so a busy list screen adds up fast.
  • Phone (SMS) login only works on Blaze and is billed per SMS sent, on top of the free 50k users.
  • The database location is permanent: pick a far-away region by mistake and your users stay farther from their data for good.
  • Free projects are paused after one week without activity, and you get only 2 free projects across all your organizations.
  • The built-in email only reaches members of your Supabase team, at about 2 emails an hour. Real users get no confirmation or reset email until you plug in your own SMTP.
  • Phone login doesn't send SMS by itself: you open an account with Twilio, MessageBird or Vonage and pay them per message.
  • The free plan has no automatic backups; Pro keeps 7 days, and point-in-time restore is an add-on of about $100/month.
  • The Pro fee is per organization, but each project runs its own server: every extra project adds compute (Micro is $10/month) on top.
Price checked

Checked on Oct 28, 2026 · official pricing

Checked on Oct 28, 2026 · official pricing

Checked on Oct 28, 2026 · official pricing

Prices are read from each official pricing page on the date shown and can change. Always confirm before signing up.

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