Note: Robocode Repository is now back up on a temporary server until the new Rails-based site is ready.
Robocode: Home Page

Robocode is swiftly bringing the productivity of the world's IT departments to a complete halt as thousands of developers discover that they aren't the only ones who dream of programming their own battle bots.

Robocode is a game where you use Java to program one or more robots to do battle in an arena against each other. The guys over at IBM's AlphaWorks have produced one of the most captivating games to hit the net in years. To get started, head on over to their website and download the game (for FREE!).

Be sure to checkout their tutorial and start making and uploading your own bots! If you have questions or need some ideas or examples on how to build your bot then visit the 'FAQs and Tutorials' section of our 'Other Sites' page.

 May 18, 2006
We finally switched over to Tomcat
We have been using Orion app server for ever. However, it was occasionally running out of memory (especially in the past week) - so, we decided to finally switch over to hosting the site on Tomcat. We had been developing and tweaking stuff (way back) using Tomcat on our development machines. So, it should be pretty stable. Let us know if you run into any problems. By the way, the problem with the forums where it would show a NullPointerException was caused by a Jive config file corruption that occured nearly every time that Orion ran out of memory. Hopefully, the forums will be more stable now. As always, if you find any bugs, please let us know in the forums or via an email to Thanks!

 November 30, 2003
Forums are back online!
The forums are now back online and all previous data is intact. This was a bit of a challenge because the MySQL schema for the forums was lost. So, we (actually the mythical Jason) translated the Oracle schema over to MySQL. It took a couple attempts - but we finally got it. Therefore, the whole site has finally made the transition to the new server and from Oracle to MySQL. As always, if you find any bugs, please let us know in the forums or via an email to Thanks!

 November 29, 2003
Bots Uploads Fixed! (again)
This actually looked like a download bug because the bots would fail to download. However, what actually happened was that the bots silently failed during upload. Thus, there were no bot files to be downloaded. Emails have been sent out to the people who uploaded bots on the 28th and 29th. They will be re-uploading their bots soon. Please report any new bugs via email to

 November 28, 2003
Bots uploads/downloads back online!
We were actually back online earlier in the week. But we didn't notice that there was a slight variance between our development environment and the production environment where the JSP compiler intrepreted the import statement a little differently. Thus, our dev environment testing didn't reveal the upload bug in the prod environment. It wasn't until we noticed after a couple of days that nobody was uploading new bots that we decided we better do some testing on the prod environment. We probably could have figured this out faster if we had the forums back online so that people could report the bug - but they're not ready yet. So, if anyone identifies any bugs, please report them in an email to

 June 19, 2003
Most Popular Downloads Bug Fixed!
This was a little odd. It appears that some SQL that had always worked a certain way - suddenly didn't any longer. Must have been a slight change in an Oracle update that caused the interpretation of a date ran through a few functions to change. Oh well - it's fixed now!

 June 3, 2003
Major Site Update!
Actually, we're hoping that nobody notices this site update. We've fundamentally changed how the bots are stored on the server. The bots used to be uploaded/downloaded directly into binary large objects (BLOBs) on the database server. Now, the bots are uploaded/downloaded directly to the filesystem on the server. No user interface changes should be detectable.

This change was made for two reasons. First, some other (as yet un-identified) change was made to the server. This had the effect of suddenly causing our extremely stable webapp which had ran for about 6 months without a restart or any code change at all to suddenly start consuming large quantities RAM for every bot that was downloaded. This RAM never seemed to be released. This caused quite a bit of havoc when the server ran out of RAM and essentially hung - bringing many other webapps to a stand-still and killing other services running on this server. The 'fabled' Jason nearly turned into the 'dreaded' Jason as he edged closer to drastic action to preserve the quality of life for the other inhabitants of this server. Luckily, we managed to impose upon his graciousness long enough to change-out the code causing the problems.

The second reason has to do with web browser support. For some reason, even though we have gone to great lengths to follow all the protocols for performing file downloads, some browser/OS combinations still downloaded the JAR files but saved them with the wrong name (usually the name of the JSP page). This change to downloading directly from the filesystem should resolve this problem once and for all.

An additional reason (3rd of the 2 reasons) is that this sets us up to make our next site update. We are going to add the ability to keep a history of all versions of a bot that have been uploaded. Visitors to our site can download the latest version by default - or they can pick a specific older version to download. We will keep track of a description of the changes for each version as well as allow you to assign any arbitrary version name. Furthermore, We will track the number of downloads for each version of a bot while also showing the grand total. We also plan to change the upload process so that you upload the file before entering the descriptive information about the bot. This way, we can automatically fill out most of this info from the properties entered when you packaged your bot for upload.

If anybody encounters problems with the site, please let us know about it in the forums. Thanks!

 April 2, 2003
Site Outage - We're Back Online!
Our server moved to a nice new office on Friday. We moved but Qwest didn't move with us. For weeks they were like, "Everything looks perfect. We'll call Friday to do the switch" and then on Friday it was, "You placed a move order?"

So after much panic and a few days of network wrangling, we are back online! Sorry for any inconvenience that this may have caused to the robocode community.

 February 11, 2003
Site Update - Updated Other Sites Page
Added Robo Wiki, a new interactive FAQ site, to the Other Sites Page.

 November 28, 2002
Site Update - Updated Other Sites Page
Added a couple sites to the other sites page - including a very slick chinese site. In other news, we are hard at work on new upload/download functionality that will make the downloads work perfectly on all browsers. Also, this will include the ability to view and download old versions of bots and see a log of the changes made with each new version. We hope to have this new functionality ready in December.

 October 15, 2002
HUGE Site Update - Help us find bugs!
We made some really huge changes on the back end that effect just about every aspect of the site. Please, help us run down any bugs. The changes will most likely cause bugs in navigation, page validation, and browser compatibility. If you see any exception error pages, please copy the contents into an email and send it to

On the upside, this update clears the way for implementing all those features that we've been working on. The biggest of these will be the new upload/download functionality that makes use of CVS version control behind the scenes. You will be able to keep a log of all the changes made to your bots and be able to go back to any previous version. The next biggest change will be the news site functionality that will allow the robocode community to submit their own news stories and allow volunteer admins to moderate each of the news sections.

For this release, you will find that browser compatibility should be much better (actually JavaScript compatibility). Now, all those OSX users out there will finally be able to use OmniWeb to access the site.

If you notice any new odd behavior or simply have a suggestion to further improve the site, let us know about them in our forums!

 April 29, 2002
Site Update - Updated Other Sites Page
Added Qohnil's League to our Other Sites page. Are there any other sites out there that should be added to the Battle Ranking Sites section of our Other Sites page? Let us know about them in our forums!

 April 11, 2002
Site Update - New Categories
Two new bot categories have been added to support the new team oriented features in Robocode: 'Extends TeamRobot' and 'Implements Droid'. This will allow people to be able to easily find bots that have been designed specifically to work with the new team features. These new categories were suggested in our forums. Are there any others that we should be thinking about? Let us know in our forums!

 April 10, 2002
Site Update - Downloads Everywhere!
Download links for bots now appear everywhere that you see a list of bots. This includes the Bots Summary, Category List, and Search screens. Furthermore, the download link is replaced by "(No JAR)" if the bot has no JAR, ZIP, or class associated with it.

We would like to put download links on the 'Most Popular Downloads' section of the Bots Summary screen - but there are already a bunch of columns and we can't quite figure out a way to do it and make it look good. If you have any ideas or just want to let us know what you think of the change then, please, let us know about it in our forums!

 April 6, 2002
This is a HUGE accomplishment! Go get it here. Read the release notes here. This is the official 1.0 release and it is looking really good. Let us know what you think in our forums!

 Mar 24, 2002
Site Update - Downloads on Bots Summary Page
In response to a request in our forums, we have added a download link next to each bot in the Newest Bot Uploads section of the Bots Summary page. This makes it easier for everyone to download the new bots each day. Let us know what you think in our forums and keep those suggestions coming!

 Mar 8, 2002
Site Update - Better Searches
Now all search features on the site are case insensitive. All searches also perform a 'contains' search. Therefore, if you type 'lynn' in the Author field on the Bots Search page then it will return a list of all the bots submitted by both 'Dan Lynn' and 'flynn'. This should simplify searching for specific bots.

 Mar 7, 2002
Robocode Version 0.99 Available!
Now your bots can work in teams! The new APIs let you construct bots that can work together and communicate as a team. Wow! This is a great feature that has been in the works for quite a while. So, what are you waiting for? Go download the latest version now! You can read through the full list of changes here.

 Mar 7, 2002
Fantastic New Tutorial for Advanced Bots!
Nicator has put together a great new tutorial that covers many of the concepts involved in creating more advanced bots. He basically disects SnippetBot and exhaustively comments the code. This is a great learn-by-example tutorial. You can access the tutorial here.

 Mar 7, 2002
Site Update
We've spent some time going back through the site and testing browser compatibility. As a result, the site should now look much better on Mozilla and some older browsers. Also, we've added some new surprises for those with the latest browsers.

The 'FAQs and Tutorials' section of the 'Other Sites' page has been updated with all the tutorials and FAQs that we know of. Are there any other learning resources out there that should be added? Let us know in our forums!

 Mar 6, 2002
New and Improved Domain Name!
Well, it looks like our site has become a permanent part of the Robocode landscape. Therefore, we've decided to change our domain name from to The old domain name will continue to work for a while - but we will nag you with a little reminder at the top of the page to update your bookmarks if you continue to access the site with the old domain name. Let us know what you think of the new domain name in our forums.

 Feb 25, 2002
Now, Bigger Bots!
We received a request from a member of our Robocode community that the maximum bot size be increased. Currently, we were limiting uploaded JARs to a maximum size of 80k. This limit has now been increased to 160k. If there are any other great suggestions or requests out there, please speak-up in the forums! [UPDATE] There are some real mosters lurking out there. I've been informed that some may be over 200k with source. Thus, I've bumped the max up to 250k!!

 Feb 02, 2002
Ouch! Bad Month for Our Servers!
Early in January, we lost the root drive on our server. As a result, we were offline for a couple days while Jason (our fabled server guru) worked diligently to resurrect our poor server. Thanks to Jason's great skill, we were able to go back online without losing any forum or bot info. We backup all data weekly. Since the database is stored on a different drive, we didn't lose a single day's info.

Disaster strikes again! Vast regions of the midwestern United States encountered power outages lasting days after a massive ice storm passed through. Our servers rebooted three times and suffered unknown power surges and drops during this period. In fact, I'm posting this story from home where I still have no power and may not for several more days!

The only reason that I am able to use my laptop (or more importantly heat my home) is because of the heroic efforts of my brother-in-law, Mike, who lent me his backup power generator and stayed-up until 1:30am with me trying to get it running. (He had to get up and go to work a few hours later at 4:30am). Thanks Mike!

The fabled Jason's faithful sidekick Jono helped get the Robocode Repository back online (at least for now) while Jason is away on a 'work' trip in Las Vegas. We have been told that we might encounter further outages as the utility companies continue their repairs in the surrounding areas. Therefore, if you notice that the site is down, just check back a little later.

On the brighter side, development on our new News section is progressing nicely and we're preparing to launch it soon.

 Jan 06, 2002
Excellent New Robocode Tutorial
Sing Li of Wrox Press has just published a great article on Robocode over at IBM's DeveloperWorks. It is a pretty complete tutorial on how to construct a bot and better understand the whole battle simulator architecture. This is a must read!

 Jan 06, 2002
Updated Other Sites Section
Added The Gladiatorial League to the Other Sites page. It is a division-based Robocode competition site where battles are fought and result stats posted. Go check it out! If there are any other hot Robocode sites out there that should be posted in our Other Sites page, please let us know in the Suggestions for RoboCode Repository Website forum.

 Dec 21, 2001
Updated Other Sites Section
As pointed-out in our forums, some of the site links on the Other Sites page needed to be updated. Thanks!

 Dec 07, 2001
Version 0.98.2 Released! (last week)
In case anybody hasn't noticed yet, there is a new version of Robocode available over at

This is a very impressive update. Some of the major enhancements include: vastly improved performance when minimized, colorized robots, and an overall very solid fit and finish. The full list of changes can be found at

 Dec 06, 2001
Look & Feel Refinements
Notice that the left margin now has a 3D effect to it. This effect is mirrored in most page body sections. What do you think? Is it an improvement? Ideas to make it better? Let us know in the forums!

The syntax colored view source page no longer performs a hard wrap at 80 chars. Due to popular demand the source page does not wrap at all any more. These changes added about 1.5 hours to the project time.

 Dec 06, 2001
Updated Bots Summary Page
The Newest Bots Uploads and Most Popular Downloads sections have been updated to use new algorithms for determining which bots qualify.

The Newest Bots Uploads was incorrectly showing only the most recent four uploads plus any others uploaded on the same date as the fourth bot. This has been modified to display at least the last 5 uploads.

The Most Popular Downloads section has had its popularity calculation modified. This section displays the bots which are ranked as most popular by dividing the total number of downloads by the number of days since the bot was uploaded. However, the number of days was being calculated using the fractional amount of the current day elapsed minus the date uploaded at 12am. Thus, if you uploaded your bot at 1:00am then viewed the popularity rating for your bot at 1:00am then their popularity would be based on the total number of downloads divided by 1/24. Thus, the number of downloads was essentially multiplied by 24 giving very exciting popularity ratings. This has now been changed to use the number for integer days since uploaded plus one. Thus, if your bot was uploaded as described above then the popularity rating would be the number of downloads divided by one.

This change was made in response to user feedback in the forums. If anyone has ideas on better ways to calculate popularity then head on over to the forums and let us know! This modification adds 2 hours to the project time.

 Dec 06, 2001
Stocking Stuffers!
Now you can fight your battles with your friends in the real world using these really cool 4 inch long remote control tanks found at:

They can even battle each other using laser tag guns and sensors that disable the bot after enough hits. These are definately the cool stocking stuffers for this year's Robocode addict!

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