Free SQL Server Database Online: The Real Options, Their Limits, and When Postgres Is the Better Free Choice

A free SQL Server database online exists in three shapes, and they suit different people: a cloud free tier for a real application, which today means the serverless free offer on Azure SQL Database with a capped compute allowance and a 32GB size limit; a browser playground for learning and testing queries, which stores nothing you would want to keep; and SQL Server Express or the Developer edition running on your own machine or in a container, which is free without limits on time but is not online unless you make it so. Which one you need depends on whether you are learning T-SQL, prototyping a .NET application, or trying to host something for free, and for the third case the honest answer is often that a free Postgres or MySQL tier will serve the application better than any free SQL Server.

SQL Server is the one major relational engine with a licence fee attached, so free means something narrower for it than for Postgres or MySQL. The options below are ordered by what they are actually for, with the limits stated plainly, because the limits are what decide the choice.

Table of contents

• 1. Azure SQL Database free offer: the one real cloud free tier
• 2. Online SQL playgrounds: for queries, not for data
• 3. SQL Server Express and Developer edition: free, local, unlimited in time
• 4. Free tiers on general hosting providers
• 5. Trial credits on the large clouds
• The question underneath: do you need SQL Server at all?
• A decision in three questions
• How this fits the rest of the stack
• FAQ

1. Azure SQL Database free offer: the one real cloud free tier

Microsoft’s own cloud offers a free serverless Azure SQL Database with a monthly allowance of compute measured in vCore-seconds, a database size cap of 32GB, and a limit on how many free databases a subscription can hold. When the compute allowance runs out for the month, the database either pauses until the next month or starts billing, depending on a setting you choose when you create it.

• Good for: a genuine SQL Server for a small application, a staging database, or learning the managed service with real tooling.
• Limits: the compute cap is generous for a hobby project and tight for anything with steady traffic; the database auto-pauses when idle, so the first query after a quiet period is slow; you need an Azure subscription with a card on file even if you never exceed the free allowance.
• Watch for: the pause-or-bill choice. If you pick bill, a runaway query or a bot hitting your app can end the free month early and start charges.

2. Online SQL playgrounds: for queries, not for data

Several sites run a SQL Server instance in the browser for running ad-hoc queries, sharing a query with a colleague, or working through a tutorial. You paste a schema, run statements, see results. Nothing persists beyond the session or a shareable link, there is no connection string for an application, and the instance is shared and rate-limited.

• Good for: learning T-SQL syntax, testing a query before running it on a real database, reproducing a bug for a forum question.
• Limits: no persistence, no connections from outside the browser, no confidentiality. Do not paste production data into one.

3. SQL Server Express and Developer edition: free, local, unlimited in time

Microsoft distributes two free editions. Express is licensed for production use with hard caps: one socket or four cores, a small memory ceiling for the buffer pool, and a 10GB maximum per database. Developer edition is the full product with no caps, licensed for development and testing only. Both run on Windows, Linux and in a Docker container.

docker run -e "ACCEPT_EULA=Y" -e "MSSQL_SA_PASSWORD=Your_Str0ng_Pass" \
  -p 1433:1433 --name mssql -d mcr.microsoft.com/mssql/server:2022-latest

• Good for: local development, CI pipelines, a .NET application’s test database, and, with Express, small production workloads under 10GB on hardware you control.
• Limits: it is online only if you host it, which means a server with a public or tunnelled endpoint, patches, backups and a firewall. The database is free; the machine is not.
• Watch for: the licence. Developer edition in production is a compliance problem, not a technical one.

4. Free tiers on general hosting providers

Some web hosts include a small SQL Server database with their Windows hosting plans, and a few advertise a free MSSQL tier. These are typically shared instances with a size cap in the tens or hundreds of megabytes, limited concurrent connections, no guaranteed backups, and terms that allow the host to remove inactive databases. They exist to get you onto the paid plan, which is fine as long as you know it.

• Good for: a proof of concept that needs a connection string today.
• Limits: size, connections, and no promise of durability. Not a place for data you cannot recreate.

5. Trial credits on the large clouds

The major clouds give new accounts a fixed credit for a limited period, and the managed SQL Server offerings on those clouds are eligible. This is not a free tier; it is a countdown. It is the right way to evaluate a managed SQL Server at production size for a few weeks, and the wrong way to host anything you intend to keep, because the database is billing at full rate the moment the credit or the period runs out.

The question underneath: do you need SQL Server at all?

If the application is written in .NET against T-SQL, with stored procedures and SQL Server-specific types, then yes, and the Azure free offer or a local Express instance are the answers. If the application is new, or written against an ORM that speaks several dialects, the licence fee is a cost with no benefit, and the free options widen considerably.

Postgres and MySQL have no licence, so every hosting provider’s free tier for them is a free database rather than a free sample. They run on any operating system, in any container, and on any cloud, and every modern framework treats one of them as the default. A project that starts on Postgres never has to answer the question this post is about, because the engine is free everywhere and forever.

The migration in the other direction is also less frightening than it looks. Tools exist that move a SQL Server schema and data into Postgres in one command, with the type mapping handled and the stored procedures left as the one manual step. For an application that is mostly CRUD through an ORM, that is a day’s work, and it removes a recurring line from every future hosting bill.

A decision in three questions

1. Learning T-SQL or testing a query? A browser playground, or Developer edition in Docker for anything longer than an afternoon.
2. Developing or testing a .NET app that must use SQL Server? Express or Developer locally; the Azure free offer when you need it reachable from a deployed app.
3. Hosting a real application for as little as possible? Unless the code is tied to T-SQL, use Postgres or MySQL on a managed plan with backups, and let the free-SQL-Server search end here.

How this fits the rest of the stack

For the third case, the number to look at is the total for the database and the service beside it, because a free database attached to a service you pay for is not a free stack. The RunxBuild hosting calculator shows a managed Postgres or MySQL next to a service plan, with the Free tier’s fifteen free days each month and the $4 Dev plan stated as they are, so the comparison with a capped SQL Server free offer is made on the whole bill. Backups are part of the plan rather than a separate line, which is the thing most free tiers quietly leave out.

Useful related references:

• Deploy a Go Backend for Free on RunxBuild
• Deploy a Java Backend for Free on RunxBuild
• Deploy an Angular App for Free on RunxBuild
• Databases on RunxBuild

FAQ

Is there a genuinely free SQL Server database online?

Yes: the Azure SQL Database free offer provides a serverless database with a monthly compute allowance, a 32GB size cap and a limit on the number of free databases per subscription. It requires an Azure account. Beyond that, browser playgrounds are free but do not persist data, and Express or Developer edition are free to run yourself.

What is the difference between SQL Server Express and Developer edition?

Express is licensed for production with hard limits: one socket or four cores, a small buffer pool ceiling and 10GB per database. Developer edition is the full product with no limits, licensed only for development and testing. Both are free downloads and both run in Docker.

Can I host a real application on a free SQL Server tier?

A small one, on the Azure free offer, as long as traffic stays inside the monthly compute allowance and you accept auto-pause delays. Shared free MSSQL databases on web hosts are too limited and too fragile for data you cannot recreate.

Should I use Postgres instead of SQL Server for a free database?

If the application is not tied to T-SQL, stored procedures or SQL Server-specific features, yes. Postgres and MySQL have no licence fee, so their free tiers are real databases rather than samples, and they run anywhere. The engine choice removes the question permanently.

How do I run SQL Server for free in Docker?

Pull the official image and run it with ACCEPT_EULA=Y and a strong MSSQL_SA_PASSWORD, publishing port 1433. That gives you Developer edition locally for development and testing. It is not online until you host the container somewhere with a reachable endpoint, backups and a firewall.