Files and locations


An extension consists of:

  1. A directory named by the extension key (which is a worldwide unique identification string for the extension), usually located in typo3conf/ext for local extensions, or typo3/sysext for system extensions.
  2. Standard files with reserved names for configuration related to TYPO3 (of which most are optional, see list below)
  3. Any number of additional files for the extension functionality itself.

Reserved file names

This lists files within an extension that have a specific meaning by convention. TYPO3 will scan for reserved file names and use the content for specific functionality. For example, if a svg logo of your extension is placed at Resources/Public/Icons/Extension.svg, the Extension Manager will show that image.

Most of these files are not required. The exception are ext_emconf.php in legacy installations not based on Composer and composer.json in Composer installations installations.


It is recommended to keep ext_emconf.php and composer.json in any public extension that is published to TYPO3 Extension Repository (TER), and to ensure optimal compatibility with Composer installations and legacy installations.

Do not introduce your own files in the root directory of extensions with the name prefix ext_, because that is reserved.


– required in Composer installations

For more information, see composer.json.

Changed in version 11.4: The ordering of installed extensions and their dependencies are loaded from the composer.json file, instead of ext_emconf.php in Composer installations.


Extension authors should ensure that the information in the composer.json file is in sync with the one in the extensions’ ext_emconf.php file. This is especially important regarding constraints like depends , conflicts and suggests. Use the equivalent settings in composer.json require, conflict and suggest to set dependencies and ensure a specific loading order.


– required in legacy installations

Definition of extension properties.

Name, category, status etc. are used by the Extensions module in legacy installations. The content of this file is described in more details in Declaration file (ext_emconf.php).

For legacy installations the ext_emconf.php file is the source of truth for required dependencies and the loading order of active extensions.


– optional

Addition to LocalConfiguration.php. It should contain additional configuration of $GLOBALS['TYPO3_CONF_VARS'].

This file contains hook definitions and plugin configuration. It must not contain a PHP encoding declaration.

All ext_localconf.php files of loaded extensions are included right after the files typo3conf/LocalConfiguration.php and typo3conf/AdditionalConfiguration.php during TYPO3 bootstrap.

Pay attention to the rules for the contents of these files. For more details, see the section below.


– optional

Contains extensions of existing tables, declaration of backend modules, etc. All code in such files is included after all the default definitions provided by the Core and loaded after ext_localconf.php files during TYPO3 bootstrap.

Pay attention to the rules for the contents of these files. For more details, see the section below.


In old TYPO3 Core versions, this file contained additions to the global $GLOBALS['TCA'] array. This changed since Core version 6.2 to allow effective caching:

TCA definition of new database tables must be done entirely in Configuration/TCA/<table name>.php. These files are expected to contain the full TCA of the given table (as an array) and simply return it (with a return statement).

Customizations of existing tables must be done entirely in Configuration/TCA/Overrides/<table name>.php.


– optional

SQL definition of database tables.

This file should contain a table-structure dump of the tables used by the extension. It is used for evaluation of the database structure and is applied to the database when an extension is enabled.

If you add additional fields (or depend on certain fields) to existing tables you can also put them here. In that case insert a CREATE TABLE structure for that table, but remove all lines except the ones defining the fields you need, here is an example adding a column to the pages table:

      tx_myext_field int(11) DEFAULT '0' NOT NULL,

TYPO3 will merge this table definition to the existing table definition when comparing expected and actual table definitions. Partial definitions can also contain indexes and other directives. They can also change existing table fields though that is not recommended, because it may create problems with the TYPO3 Core and/or other extensions.

The ext_tables.sql file may not necessarily be “dumpable” directly to MySQL (because of the semi-complete table definitions allowed defining only required fields). But the Extension Manager or Install Tool can handle this.

TYPO3 parses ext_tables.sql files. TYPO3 expects that all table definitions in this file look like the ones produced by the mysqldump utility. Incorrect definitions may not be recognized by the TYPO3 SQL parser or may lead to MySQL errors, when TYPO3 tries to apply them. If TYPO3 is not running on MySQL or directly compatible other DBMS like MariaDB, the system will parse the file towards the target DBMS like PostgreSQL.

Auto generated structure

The database schema analyzer automatically creates TYPO3 “management” related database columns by reading a tables TCA and checking the Table properties (ctrl) section for table capabilities. Field definitions in ext_tables.sql take precedence over automatically generated fields, so the Core never overrides a manually specified column definition from an ext_tables.sql file.

These columns below are automatically added if not defined in ext_tables.sql for database tables that provide a $GLOBALS['TCA'] definition:

If uid field is not provided inside ext_tables.sql, the PRIMARY KEY must be omitted, too.
pid and KEY parent
Column pid is unsigned if the table is not workspace aware, the default index parent includes pid and hidden as well as deleted if the latter two are specified in TCA Table properties (ctrl). The parent index creation is only applied if column pid is auto generated, too.
['ctrl']['tstamp'] = 'fieldName'
Often set to tstamp or updatedon
['ctrl']['crdate'] = 'fieldName'
Often set to crdate or createdon
['ctrl']['cruser_id'] = 'fieldName'
Often set to cruser or createdby
['ctrl']['delete'] = 'fieldName'
Often set to deleted
['ctrl']['enablecolumns']['disabled'] = 'fieldName'
Often set to hidden or disabled
['ctrl']['enablecolumns']['starttime'] = 'fieldName'
Often set to starttime
['ctrl']['enablecolumns']['endtime'] = 'fieldName'
Often set to endtime
['ctrl']['enablecolumns']['fe_group'] = 'fieldName'
Often set to fe_group
['ctrl']['sortby'] = 'fieldName'
Often set to sorting
['ctrl']['descriptionColumn'] = 'fieldName'
Often set to description
['ctrl']['editlock'] = 'fieldName'
Often set to editlock
['ctrl']['languageField'] = 'fieldName'
Often set to sys_language_uid
['ctrl']['transOrigPointerField'] = 'fieldName'
Often set to l10n_parent
['ctrl']['translationSource'] = 'fieldName'
Often set to l10n_source
Column added if languageField and transOrigPointerField are set
['ctrl']['origUid'] = 'fieldName'
Often set to t3_origuid
['ctrl']['transOrigDiffSourceField'] = 'fieldName'
Often set to l10n_diffsource
['ctrl']['versioningWS'] = true - t3ver_* columns
Columns that make a table workspace aware. All those fields are prefixed with t3ver_, for example t3ver_oid. A default index named t3ver_oid to fields t3ver_oid and t3ver_wsid is added, too.


Static SQL tables and their data.

If the extension requires static data you can dump it into an SQL file by this name. Example for dumping mysql data from bash (being in the extension directory):

mysqldump --add-drop-table \
            --password=[password] [database name] \
            [tablename]  > ./ext_tables_static+adt.sql

--add-drop-table will make sure to include a DROP TABLE statement so any data is inserted in a fresh table.

You can also drop the table content using the Extension Manager in the backend.


The table structure of static tables needs to be in the ext_tables.sql file as well - otherwise an installed static table will be reported as being in excess in the Install Tool.


Static data is not meant to be extended by other extensions. On re-import all extended fields and data is lost due to DROP TABLE statements.


Preset TypoScript constants. Will be included in the constants section of all TypoScript templates.


Use such a file if you absolutely need to load some TS (because you would get serious errors without it). Otherwise static templates or usage of the Extension Management API of class TYPO3\CMS\Core\Utility\ExtensionManagementUtility are preferred.


Preset TypoScript setup. Will be included in the setup section of all TypoScript templates.


Use such a file if you absolutely need to load some TS (because you would get serious errors without it). Otherwise static templates or usage of the Extension Management API of class TYPO3\CMS\Core\Utility\ExtensionManagementUtility are preferred.


Extension Configuration template.

Configuration code in TypoScript syntax setting up a series of values which can be configured for the extension in the Install Tool. Read more about the file format here.

If this file is present ‘Settings’ of the Install Tool provides you with an interface for editing the configuration values defined in the file. The result is written as an array to LocalConfiguration.php in the variable $GLOBALS['TYPO3_CONF_VARS']['EXTENSIONS'][*extension_key* ]


Full path to this file is: Configuration/RequestMiddlewares.php.

Configuration of user-defined middlewares for frontend and backend. Extensions that add middlewares or disable existing middlewares configure them in this file. The file must return an array with the configuration. For more details, see Configuring middlewares.

Routes.php and AjaxRoutes.php

Full paths to these files are: Configuration/Backend/Routes.php and Configuration/Backend/AjaxRoutes.php.

Registry of backend routes. Extensions that add backend modules must register their routes here to be correctly linkable in the backend. The file must return an array with routing details. See Core extensions like backend for examples.


New in version 10.

Services can be configured in this file. TYPO3 uses it for:

A typical Configuration/Services.yaml may look like this:

Simplified Services.yaml from sysext: core
# Configuration/Services.yaml
   # general settings
      autowire: true
      autoconfigure: true
      public: false

      resource: '../Classes/*'

   # dependency injection (override public setting)
      public: true

        - name: 'console.command'
          command: 'mailer:spool:send'
        - name: 'console.command'
          command: 'swiftmailer:spool:send'
          alias: true
          schedulable: false

See also


Alternatives: Resources/Public/Icons/Extension.png, Resources/Public/Icons/Extension.gif

SVG, PNG or 18x16 GIF extension icon

If it exists, this icon is displayed in the Extension Manager. Preferred is using a SVG file, because the extension icon will look nicer as a vector graphic (SVG) rather than a bitmap (PNG or GIF).

Reserved Folders

In the early days, every extension author baked his own bread when it came to file locations of PHP classes, public web resources and templates.

With the rise of Extbase, a generally accepted structure for file locations inside of extensions has been established. If extension authors stick to this and the other Coding Guidelines, the system helps in various ways. For instance, if putting PHP classes into the Classes/ folder and using appropriate namespaces for the classes, the system will be able to autoload these files.

Extension kickstarters like the Extension Builder extension will create the correct structure for you.

It is described below:

Contains all PHP classes. One class per file. Should have sub folders like Controller/, Domain/, Service/ or View/. For more details on class file namings and PHP namespaces, see chapter namespaces.
Contains MVC Controller classes.
Contains MVC Domain model classes.
Contains data repository classes.
Helper classes used in (Fluid) views.
General configuration folder. Some of the sub directories in here have reserved names with special meanings. All files in this directory and in the 2 sub directories TCA and Backend are automatically included during the TYPO3 bootstrap.
Contains backend routing configurations. See files description of Routes.php and AjaxRoutes.php above.
One file per database table, using the name of the table for the file, plus “.php”. Only for new tables.
For extending existing tables. General advice: One file per database table, using the name of the table for the file, plus “.php”. For more informations, see chapter Extending the TCA Array.
page TSconfig, see chapter ‘page TSconfig’ in the TSconfig Reference. Files should have the file extension .tsconfig.
User TSconfig, see chapter ‘user TSconfig’ in the TSconfig Reference. Files should have the file extension .tsconfig.
TypoScript static setup (setup.typoscript) and constants (constants.typoscript). Use subfolders if you have several static templates.
Contains the extension documentation in ReStructuredText (ReST, .rst) format. Read more on the topic in chapter extension documentation. Documentation/ and its subfolders may contain several ReST files, images and other resources.
This file contains the cover page of the extension manual in ReST format. The name or format of the file may not be changed. You may include other ReST files as you like. See the “Extension Template” on for more information about structure and syntax of extension manuals.
Contains the sub folders Public/ and Private/, which contain resources, possibly in further subfolders, e.g. Templates/, Css/, Language/, Images/ or JavaScript/. This is also the directory for non–TYPO3 files supplied with the extension. TYPO3 is licensed under GPL version 2 or any later version. Any non–TYPO3 code must be compatible with GPL version 2 or any later version.
XLIFF files for localized labels.
Main layouts for (Fluid) views.
Partial templates for repetitive use.
One template per action, stored in a folder named after each Controller.

Public assets of extensions (files that should be delivered by the web server) must be located in Resources/Public folder of the extension.

Deprecated since version 11.5: Having public assets in any but the folder Resources/Public has been deprecated with version 11.5.

Any CSS file used by the extension.
Any images used by the extension.
Any JS file used by the extension.
Contains unit tests and fixtures.
Contains functional tests and fixtures.