My impressions of Fat-Free Framework for PHP

After wasting far too much time trying to rebase my Gender-Bending Fiction Index on top of CakePHP, I decided that I’d give it one more try before consigning it to the list of things indefinitely on hold… and I’m glad I did.

My first concern was to avoid failing because of “too much convention”. CakePHP is a nice framework, but if I’m going to be letting a framework reduce my site’s performance by an order of magnitude, it had better give me some proportionate benefit.

(Like many web hosts, mine doesn’t run a PHP bytecode cache. That means that any representative “Hello World” for a big-name framework like CakePHP or Zend or CodeIgniter will generally serve 100 requests per second on hardware that’ll do 1000 with bare PHP. It’s just a side-effect of PHP only letting compiled extensions stay resident between requests.)

I don’t remember exactly how, but I ended up searching for PHP micro-frameworks, and stumbled across Fat-Free Framework 2.x.

At the highest level, the important things to know about it are:

  • The closest PHP analogue I’ve yet found to Bottle.
  • GPLv3-licensed with the option to buy your way out of it
  • Requires PHP 5.3 for its anonymous function support (Think JavaScript)
  • In every performance benchmark I’ve been able to dig up, it’s generally in the same ballpark as bare PHP.
  • Includes a simple template language, URL routing, a ton of useful helpers, and ORMs for SQL, NoSQL, and flat-file data storage.
  • Easy to swap out pretty much anything but the URL router.
  • The core, plus all included plugins, weighs in at 288KiB.

I haven’t spent that much time with it yet, and I didn’t need things like CAPTCHA-generation, Google/Yahoo/Twitter/Akismet API wrappers, RSS/Atom parsing, OpenID integration, Identicons, Thumbnailing, etc., but here’s what I’ve poked around with so far:


…being the most important part of any framework.

F3’s documentation isn’t the best in existence, but aside from one small rough edge to be wary of, it was definitely good enough for me.

Specifically, the website seems to be exclusively focused on the tutorial-style guides to using various features, so unless you read carefully, you’ll assume there are no API docs. I used the CHM-format copy of the API docs included in the archive at lib/f3.chm.


Requiring PHP 5.3 allows F3 to really shine when it comes to architecture. Not only do you get to feed in an anonymous function anywhere that older frameworks might require you to reference things by strings, but it also makes heavy use of classes to implement minor fixes for PHP rough edges. (While still giving you a choice between procedural and object-oriented styles for your own code that is satisfyingly reminiscent of Python.)

For example, one of the big rough edges I’ve seen for people coming from other languages is PHP’s scoping rules for globals. F3 works around this by offering you the option of using its own internal globals system via F3::set and F3::get. (And including a shorthand for it in its template language)

This “offer a streamlined alternative, but don’t force it” pattern is present throughout the framework. For example, Web::isajax is the familiar boolean-outputting check for XMLHttpRequests and Web::http lets you perform an HTTP request and retrieve the content in one line and is based on fsockopen() for portability.

It also includes a nice, simple config file parser in the core which populates the same data store it looks to for configuration (F3::set/get, again) , which makes good project architecture much simpler.

URL Routing

Nice and simple, yet very powerful.

F3’s URL routing works by taking a string like GET /s/@story_id/* and mapping it to your choice of:

  • An anonymous function
  • A comma-separated list of PHP files to require
  • A comma-separated list of functions or methods to execute (It’ll instantiate the classes for you)

It’s also fully compatible with:

  • PHP 5.3 namespaces
  • Autoloading
  • The use of non-GET/POST HTTP methods
  • Defining your permanent redirects in your routing table
  • Defining routes in an INI-format config file if that’s what you prefer
  • Dynamic routes which look up classes or methods at runtime. (Python programmers will recognize this pattern from Pylons)


Basically something half-way between PHP and Django-style templates, but it is a plugin, so you don’t have to waste the kilobytes if you prefer something else.

It uses XML syntax like <F3:check if="..."> for the block-level stuff and, aside from the need for <F3:true> and <F3:false> when defining an else case, it’s actually not that bad.

There’s no inheritance syntax though, so if the more PHP-esque <F3:include href="{{@child_template}}"> doesn’t do it for you, I suggest hooking in Twig instead.

The include syntax is where it really shines though. F3 basically aliases a Django-style {{...}} syntax to <?php echo ... ?> and provides a shorthand for accessing its alternative to PHP globals: {{@orm_result->title}} and {{@array.key}}.

Despite the ability to embed raw PHP in the {{..}} blocks, the usual caveats for Django-style templates apply.  Don’t try too hard to circumvent the separation between logic and presentation or you’ll bump up against the limits of the language. (For example, you can only use functions in bare {{...}} chunks, not as a source for the looping construct.)


I’ve only used the SQL ORM and only with SQLite so far, but I quite like it. It doesn’t do joins, recommending that you use CREATE VIEW in your database schema instead, but it’s truly zero-configuration. Just instantiate Axon with a table/view name, and you’re ready to go.

That may seem like a downside, but remember two things:

  1. It’s a 23KiB plugin that you’re free to replace with a beefier ORM.
  2. This approach actually makes it a lot easier to build on a database that already exists.

I actually prefer it this way, since I’m using F3 to rewrite an existing, horrendously messy PHP app in a cleaner way.


Here are the helpers I haven’t yet tried which you’ll probably want to know exist:

  • Forms
  • Profiler and Debugging
  • Unit Testing
  • Spam DNS Blacklist integration

Here’s what I have to say about the few helpers I have used so far:

CSS/Javascript Minifier
Works great for CSS, but there’s something about my Javascript that it mangles. Probably not a big issue since most of my JS is pre-minifed plugins and it’ll be the work of a minute or two to whip up something that concatenates a few K of un-minified local JS onto the dozens of kilobytes of pre-minified jQuery UI.
XML Sitemap Generator
Simple and easy to use, but there’s no way to tell it to ask search engines to index less frequently than the cache timeout and, on a database-backed site, the runtime complexity of walking the site (even without HTTP round-trips) makes it unfeasible.


I’d use it as a basis for my PHP creations any day of the week. (Of course, I always GPL them anyway) It’s ultra-light (both for size and performance), easy to plug other bits and pieces into, and adapts to my style, rather than expecting me to adapt it its conventions.

CC BY-SA 4.0 My impressions of Fat-Free Framework for PHP by Stephan Sokolow is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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18 Responses to My impressions of Fat-Free Framework for PHP

  1. Alex says:

    If only it were MIT like bottle, Silex, FuelPHP, Cake or BSD like Kohana or Yii. Or even GPLv3 across the board, so it’s at least clear if you can use it for Saas. Why invest your time in something you don’t even know if you can use for Saas? The licensing just kills it for me. I’m not the only one

    • You can use GPLed server-side code for SaaS. It’s the AGPL (Affero GPL) you have to watch out for.

      You only need to share your modifications to GPLed code if you distribute binaries. It’s essentially MIT-like if you never distribute them, which is why the AGPL was created.

      Is there some bit of it I missed that’s under a license stricter than the GPLv3 or that requires you to use GPLed CSS or Javascript?

      • Alex says:

        If it’s okay for SaaS, maybe you could persuade Bong to note that on the website, please? You seem to be in tight with him. That would do a lot IMO to clarify the license and probably make the community more active in the long run and get people sharing their projects built with it if the license were more clear.

        I find the licensing unclear right now because the GPL license contained in the download seems to support what you are saying, but the website is worded to read that “for academic and personal use” it’s GPLv3. And doesn’t say what it is for other uses. It’s says:

        Permissive and “closed-source” licensing terms are available if you intend to use the software for business or commercial gain. For academic and personal use, the PHP Fat-Free Framework and other files included in the distribution are subject to the terms of the GPL v3. You may not use the software, documentation, and samples except in compliance with the license.

        If you feel that this software is one great weapon to have in your programming arsenal, it saves you a lot of time and money, use it for commercial gain or in your business organization, please consider making a donation to the project. A significant amount of time, effort, and money has been spent on this project. Your donations help keep this project alive and the development team motivated. Donors and sponsors get priority support (24-hour response time on business days).


        I’m happy to donate if it’s okay for SaaS and that’s clear, because then I’ll invest my time into building something with it. But with it being unclear what licensing applies to SaaS given the way the site is worded currently, it’s not even worth spending the time learning or contributing to IMO because who wants to open themselves to potential legal risks of an unclear license when there are other good frameworks out there with clear licensing.

        I think the ideal solution would just be for the licensing section on the website to be reworded. For him to just say it’s GPLv3, period. And that closed source licensing terms are available if you intend to distribute it as part of closed-source, commercial software. That would make sense, be clear and be fair IMO.

        This isn’t to be critical of F3 project itself. Just the licensing.

  2. Sakshi says:

    F3 looks nice…

  3. I decided to base a project on Fat Free thanks to this blog post. Very well written, insightful stuff. Enjoy the Flattr!


  4. Alexander Morales says:

    I thinks is very easy to understand, but needs more documentation in order to get on it more quickly.

    Nice job.

  5. Informative Blog

    Thanks for Sharing !!

  6. Jo says:

    Il like and i nedd expla

  7. grails says:

    I will use F3 anytime on my personal projects. But I wonder why companies loves to choose CakePHP. It seems hard to convince corporates of such a low footprint frameworks

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  9. pcrikos says:

    It looks really simple, without the complexity of other popular php frameworks. It lets you write and organise your code the way is suitable for your project.

  10. Eugen W says:

    There is a basic way to “join” fields from other tables, see “Virtual Fields” in the user guide.

  11. Utomo says:

    Hi stephan,

    Many things happened since you write this article on 2011 and now 2014.
    I hope you can write new article about F3

  12. Credo Systemz says:

    This blog really helpful to everyone and having clear explanation so easy to understand.. thank you for sharing

    [Ed.: In line with site policy, non-constructive comments such as this have their URL field erased before being approved.]

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