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The Java runtime runs executable JAR files on JDK 25: bots, workers, APIs and websites. You build the JAR on your machine, and Square Cloud starts it with java -jar.

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Before you begin

  • A Java Development Kit (JDK) on your machine. If you don’t have one yet, you can download Eclipse Temurin from Adoptium.
  • A Square Cloud account: sign up with your email or GitHub.
  • An active plan. See the plans and pick the one that fits your project.

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Configure Square Cloud

If you upload your application through the dashboard, you can skip this section: the dashboard creates the squarecloud.app configuration file for you.

Configuration file reference

The squarecloud.app file tells Square Cloud how to run your application: its main file, memory, runtime version, name and, for a website, its subdomain.
Point MAIN to your JAR. A complete configuration file for each kind of app:
squarecloud.app
MAIN accepts up to 32 characters. For a longer path, replace it with RUNTIME=java and START=java -jar <path-to-your.jar>.

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What Square Cloud runs

  • If the START field is not defined in the configuration file, Square Cloud will execute java -jar MAIN, where the file specified in MAIN is the JAR file. If the START field is defined, the value in it will be executed directly. For more information about configuration file parameters, visit configuration parameters.

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Port and host for websites and APIs

Square Cloud sets the PORT environment variable to 80. Your server must listen on that port and on all network interfaces (0.0.0.0). With Spring Boot, set server.port=${PORT:80} in application.properties, as shown in the Spring Boot guide.

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Prepare the project

Square Cloud does not compile Java projects: build an executable JAR on your machine and upload it.
  • Maven: run mvn package; the JAR is written to target/. To bundle your dependencies into a single runnable JAR, use the Maven Shade or Assembly plugin and configure it to set Main-Class.
  • Gradle: run ./gradlew build (or gradle build); the JAR is written to build/libs/. To bundle your dependencies, use the Shadow plugin (./gradlew shadowJar) or set Main-Class in the jar task’s manifest.
Check that the JAR starts with java -jar your-app.jar before uploading it. Compile it for Java 25 or earlier: the runtime cannot run classes built for a newer Java.

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Required files

  • squarecloud.app, at the root of the ZIP.
  • Your executable JAR, set in MAIN. Its META-INF/MANIFEST.MF goes inside the JAR, not as a separate file, and must declare the Main-Class of your application.
The configuration file (squarecloud.app) must be located at the root of the zip file. Otherwise, Square Cloud will not be able to find it during deploy.

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What to leave out

  • Your source code and build folders are optional: the JAR already contains the compiled application.

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Framework guides

Spring Boot

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Troubleshooting

The JAR has no Main-Class in its manifest, so java -jar cannot start it. Build an executable JAR as described in Prepare the project.
The JAR was compiled for a newer Java than JDK 25. Build it for Java 25 or earlier.
For other problems, see Troubleshooting.

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Deploy

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Via dashboard

1

Access the Upload Page

Access the upload page and upload your project zip file.
2

Configure Your Environment

After uploading your zip, you will need to configure the name, main file or runtime environment and other settings for your project.
If you are uploading a web project, make sure to select “Web Publication” and set a subdomain to your project.
3

Deploy Your Project

Finally, click on the “Deploy” button to host your project on Square Cloud.
After deployment, you can monitor your project’s status and logs from the dashboard.
Uploading application to Square Cloud
4

Confirm Your App Is Live

Your first deploy usually takes less than a minute. In the dashboard, wait for your application status to show as running and check the logs for any startup errors.
If you deployed a website or API, open https://<your-subdomain>.squareweb.app in your browser: you should see your application responding. If you deployed a bot, send it a command to confirm it is online.
App not starting? See the Troubleshooting guide for the most common causes and fixes.

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Via CLI

To use this method, your project needs a configuration file named squarecloud.app at its root. It tells Square Cloud how to run your application.

Configuration file guide

Learn how to create the squarecloud.app configuration file that defines your application’s environment.
1

Install the CLI

Install the Square Cloud CLI. If you already have it, run the same command to update it:
2

Log In

Run the command below. It opens your browser: approve the login there and the CLI is ready. There is no API key to copy. For scripts and CI, see CLI authentication.
3

Upload Your Project

From your project folder, run the command below. The CLI zips the current folder, leaving out what squarecloud.ignore lists, and uploads it:
To upload a zip you created yourself, pass it with --file:
4

Confirm Your App Is Live

Your first deploy usually takes less than a minute. Check your application status and logs directly from the terminal:
If you deployed a website or API, open https://<your-subdomain>.squareweb.app in your browser: you should see your application responding. If you deployed a bot, send it a command to confirm it is online.
App not starting? See the Troubleshooting guide for the most common causes and fixes.

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Next steps

Environment variables

Keep secrets and settings out of your code and read them at runtime.

Custom domain

Serve your app on your own domain, on the Standard plan and above.

Troubleshooting

Fix an app that does not start or a site that does not respond.

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Contact us

If you continue facing technical difficulties, our specialized support team is available to assist you. Contact us and we’ll be happy to help you resolve any issue: support quality is a big part of why developers rate Square Cloud 4.9/5 across 402 reviews on Google and Trustpilot.