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-- required


While the file composer.json is currently not strictly required for an extension to function properly, it is considered bad practice not to add one. That is why we classify it as "required".

Including a composer.json is strongly recommended for a number of reasons:

  1. The file composer.json is required for documentation rendering since May 29, 2019.

    See Register for for more information on the necessary changes for extension documentation rendering.

  2. Working with Composer in general is strongly recommended for TYPO3.

    If you are not using Composer for your projects yet, see Migrate TYPO3 Project to Composer in the "Installation & Upgrade Guide".

Minimal composer.json

This is a minimal composer.json for a TYPO3 extension:

  • The vendor name is Vendorname

  • The extension key is my_extension


  • The namespace will be Vendorname\MyExtension

  • The package name will be vendorname/my-extension

 2    "name": "vendorname/my-extension",
 3    "type": "typo3-cms-extension",
 4    "description": "An example extension",
 5    "license": "GPL-2.0-or-later",
 6    "require": {
 7        "typo3/cms-core": "^9.5 || ^10.1"
 8    },
 9    "extra": {
10        "typo3/cms": {
11            "extension-key": "my_extension"
12        }
13    },
14    "autoload": {
15        "psr-4": {
16            "Vendorname\\MyExtension\\": "Classes/"
17        }
18    }




<vendorname>/<dashed extension key> "Dashed extension key" means that every underscore (_) has been changed to a dash (-). You must be owner of the vendor name and should register it on packagist. Typically, the name will correspond to your namespaces used in the Classes folder, but with different uppercase / lowercase spelling, e.g. GeorgRinger\News namespace and georgringer/news name in composer.json.



Description of your extension (1 line)



Use typo3-cms-extension for third party extensions. This will result in the extension to be installed in {web-dir}/typo3conf/ext instead of vendor/{vendor}/{package}.

Use typo3-cms-framework for system extensions. They will be installed in web-dir/typo3/sysext.

See typo3/cms-composer-installers (required by typo3/cms-core).



Has to be GPL-2.0-only or GPL-2.0-or-later. See:



At the least, you will want to require typo3/cms-core. You can add other system extensions and third party extensions, if your extension depends on them.



Define namespace - path mapping for PSR-4 autoloading. In TYPO3 we follow the convention that all classes (except test classes) are in the directory Classes.



Not providing this property will emit a deprecation notice and will fail in future versions.


The property "extension-key" means the literal string "extension-key", not your actual extension key. The value on the right side should be your actual extension key.

Example for extension key bootstrap_package:

   "extra": {
      "typo3/cms": {
         "extension-key": "bootstrap_package"


(usually not required)

replace in a composer.json file specifies which other packages can be replaced by this package. This means that packages with different vendor name or package name will be treated as the same package by Composer.

Example for extension key bootstrap_package:

   "replace": {
      "typo3-ter/bootstrap-package": "self.version"

As all extensions available in the TER can be installed with composer require typo3-ter/ext-key, this makes sure that there will be no conflicts with packages installed or required via Packagist or from another source.

Since the TER Composer repository is deprecated and not all extensions must be available in TER, this property is usually not required.

Properties no longer used


(not recommended)

Was used in earlier TYPO3 versions. For versions 7.6 and above you should not use the version property. The version for the extension is set in the file ext_emconf.php.

More Information

Not TYPO3 specific:

TYPO3 specific: