TYPO3 is known for its extensibility. However to really benefit from this power, a complete documentation is needed. “Core APIs” and its companion, “Inside TYPO3”, aim to provide such information to developers and administrators. Not all areas are covered with the same amount of details, but at least some pointers are provided.

“Inside TYPO3” contains the overall introduction to the architecture of the TYPO3 core. It also contains API descriptions to a certain degree but mostly in the form of examples and short table listings. “Core APIs” goes into much more detail about such APIs and covers subjects more closely related to development.

These documents do not contain any significant information about the frontend of TYPO3. Creating templates, setting up TypoScript objects etc. is not the scope of these documents; they are about the backend part of the core only.

The TYPO3 Documentation Team hopes that these two documents, “Inside TYPO3” and “TYPO3 Core APIs”, will form a complete picture of the TYPO3 Core architecture, the backend and be the reference of choice in your work with TYPO3. It took Kasper more than a year to get the first version published and we’ve tried to maintain it as best we could.

What’s new

This version is updated for TYPO3 CMS 6.2.

Many recent changes in the TYPO3 CMS code base were documented in this new version of Core APIs, some dating back to version 6.1. The release of a new LTS version was the opportunity to put extra efforts into the manuals.

Highlights from new features brought by TYPO3 CMS 6.2:

  • an Application Context, backported from TYPO3 Flow.
  • changes to the caching framework, in particuler the new cache groups.
  • well-known folder t3lib is now gone and so is constant PATH_t3lib.
  • a new API for registering AJAX handlers which provides CSRF protection (documentation yet missing, but will come very soon).
  • the system categories API has matured and the related chapter was extended. In particular, it is now possible to have more than one categories field per table.
  • usage of flash messages in Extbase has changed.
  • it is possible to define a custom mirror to fetch extension translations from.

Code examples

Many of the code examples found in this document come from the TYPO3 Core itself.

Quite a few others come from the “examples” extension which is available in the TER. You can install it if you want to try out these examples yourself and use them as a basis for your own stuff.

Yet some other examples just belong to this manual. Some may be moved to the “examples” extension at some later stage.


For general questions about the documentation get in touch by writing to .

If you find a bug in this manual, please be so kind as to check the online version on From there you can hit the “Edit me on GitHub” button in the top right corner and submit a pull request via GitHub. Alternatively you can just file an issue using the bug tracker:

Maintaining high quality documentation requires time and effort and the TYPO3 Documentation Team always appreciates support. If you want to support us, please join the documentation mailing list/forum (


This manual was originally written by Kasper Skårhøj. It was further maintained, refreshed and expanded by François Suter.


I want to dedicate this document to the people in the TYPO3 community who have the discipline to do the boring job of writing documentation for their extensions or contribute to the TYPO3 documentation in general. It’s great to have good coders, but it’s even more important to have coders with character to carry their work through till the end - even when it means spending days writing good documents. Go for completeness!

- kasper