Pete Freitag Pete Freitag

Laszlo Vs Flex

Published on October 06, 2004
By Pete Freitag

Now that Laszlo is open source and Flex has a free Non-Commercial License it is safe to assume that we will be seeing increased interest in server side swf generation.

My question, and I'm sure many other people have this question is - Now that Laszlo is free (but you can still purchase support), what can Flex do that Laszlo can't? And also what can Laszlo do that Flex cannot?

The closest thing I found to a comparison is this forum thread on Laszlo's site. But it was posted while Flex was in Beta, so not much was said about flex - its also probably a bit Laszlo biased.

laszlo flash flex ria

Laszlo Vs Flex was first published on October 06, 2004.

If you like reading about laszlo, flash, flex, or ria then you might also like:

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Price is one thing, but to me the thing that makes Laszlo a more viable solution is that Laszlo will run on versions of Flash down to version 5. Flex requires Flash 7.

This eliminates a large user pool, and therefore makes Flex a viable solution for intranets only where the Flash version can be controlled.

For a public facing site, I would not use a solution that is not useable by even 5% of visitors.

On the down side for Laszlo... no support for Unicode ( due to the Flash 5 requirement I think. )
by Steve Gustafson - Jaxfusion on 10/19/2004 at 7:56:26 AM UTC
The only downside I see w/ using Laszlo is that it doesn't run on JRUN4.
by Greg Longfield on 10/22/2004 at 1:12:44 PM UTC
Laslzo VS. Flex hmmm.... This question has been keeping me up at night! I think that Flex has some major advantages in performace and development environment. I have been in J2EE development for years now and I like how Macromedia has adopted "TagLibs" this makes integration much easier. Laszlo on the other hand is open-source so it seems to be a great place to start for small businesses looking to start developing RIA's. This debate will be won by creating an "OPEN" standard for RIA's that run on any J2EE server without expensive plugins. For now I think I'm going to stick with Laszlo simply because of the cost factor.
by Kristopher Kleva on 02/22/2005 at 2:24:08 AM UTC
Google's gmail made javascript xmlhttprequest object and other interface goodies into a cool app, CF should copy this while staying with flex as language to make this kind of interface.
by Dan on 07/15/2005 at 10:12:13 PM UTC
Flash 8 does something Laszlo doesn't and it's got me stumped trying to find a work-around.

FlashType ... an awesome font rendering engine is only available in 8 and compared to Laszlo's font rendering, well there is no comparison!
I need to build a text-viewer that has flash 8-type advanced anti-aliasing & font rendering but I need it to have an RIA back-end like Flex or Laszlo.

I don't have the budget or the stomach for the co$t of the Flex server. But Laszlo stops at Flash 7! Does anyone have a suggestion for combining the Laszlo architecture with a Flash 8 text -viewing widget? Or a better solution for rendering fonts?
by David Gibbons on 10/17/2005 at 10:19:04 PM UTC
Laszlo didn't stop at Flash 7! OpenLaszlo3.1 allows compilation to SWF8, and you can call any Flash AS interface in your LZX code. Note that using Flash-specific APIs in your Laszlo app makes your code non-portable so it may not work on all runtimes.

You should propose a fix and then contribute to the OpenLaszlo platform!
by Elliot on 01/19/2006 at 12:12:53 PM UTC
The one advantage I see to OpenLaszlo is it's ability to compile into SWF files OR DHTML. However, the component base and developer community is much larger for Flex. The new FlexLib( provides some excellent additions that seem to be lacking in Laszlo. For example, check out the fire and cloud creation components. Flex seems to have Laszlo beat on the graphics/animation side.
by DR V on 04/05/2007 at 8:41:24 PM UTC
I (and my coworkers) have quickly jumped onto the OpenLaszlo bandwagon. We find that it is a great fit for what we are trying to do.
However, one of our concerns has been how to display/manipulate a Google Map (or possibly Yahoo Map) within an OpenLaszlo application.
Today, I came across this thread and tried out the samples found at, as posted above. But it doesn't seem to work simply out-of-the-box. (And all I can do is download the files from the site.)
I also tried the following link, but the page is just empty.
Can anyone point me to an explanation of how to use the files?
by Willie on 04/06/2007 at 9:56:47 AM UTC
Hi guys,

have you tried to make a reasonably large size of application with laszlo. I tried and the xml based laszlo language is simply not a programming language.
I am scared the project getting unmanageable..
by rashomon on 10/11/2007 at 2:35:43 AM UTC
Thanks for the detailed write-up Hans. Full disclosure: I work for Laszlo Systems, which is the corporate sponsor of the OpenLaszlo platform. There are a couple of points you made that I wanted to address:

You mentioned that the simplistic Flex application you made performed substantially faster than the OpenLaszlo one. My experience is that comparable real-world OpenLaszlo applications perform about the same as their Flex counterparts, in application size, startup time, and runtime performance. A simplistic app may highlight issues that do not become apparent as the application increases in complexity. I'd like to see the OpenLaszlo application you built; it's possible that there's a simple fix that would make it perform equally - or even better ;). You'll find a lot of highly complex, publicly-deployed OpenLaszlo applications at the URL below, and I'm sure that you'll find that they perform quite well:

Regarding the double-click handling, I think I know exactly what you're referring to, because I filed this bug on it some time ago:

If you look at the history of the bug, you'll notice that we received a contributed fix that addressed the issue, and that we tried to integrate it, but ran into issues doing so. Those issues were never addressed by the contributor, which is why you had difficulty listening for the ondblclick event of grid.

Note that I'm not trying to blame anything on the contributor in this case; we are always grateful to developers who wish to help with the OpenLaszlo project. Instead, I'd like to point out that open source software - which you professed to love in your opening paragraph - is often dependant on the voluntary contributions of willing developers. This is a fact-of-life of open source software.

It may even be a testament to the power of OpenLaszlo that you were able to work around the double click issue. Do you see yourself being able to apply a similar workaround to a missing feature of the Flex grid?
by Antun Karlovac on 10/26/2007 at 3:31:54 PM UTC
Alex - there are sometimes changes that happen with new releases. There is a script provided to help with migration. I think its a problem all-around -- moving between Flash versions is not always a picnic either in my experience. (I used to work for Macromedia, now I work for Laszlo. I've seen similar issues in every developer platform I've worked with including writing native code with OS libraries and frameworks.)

General comments:
From a performance perspective, it is true that OpenLaszlo used to be slower than Flex, but with the just released OL 4.2, you can see that if you compile to SWF9 OL is slightly faster than flex:

OpenLaszlo still provides SWF8 support since those folks who do consulting still run into sites that don't have the Flash 9 adoption that Adobe reports (or product managers who are very conservative). The performance argument is a good one and can usually sway customers to the new version, but it is nice to be able to write code that will still compile to the older version of Flash without needed to switch languages.

by Sarah on 01/07/2009 at 11:19:39 AM UTC
Hi All

Thanks for the reviews, I'm new to UI patterns/tools.
Can someone make Flex and Laszlo licensing issues more clear as I need a cheap and stable UI SDK for small scale application.

-- Anish Sneh
by Anish Sneh on 11/18/2010 at 3:39:53 AM UTC