app /wiki


A competition to create an application using only 5K (5120 bytes) of code and resources.


5K is pretty small. It's about enough to show an idea. Working the constraint will require some creative thinking. With a 5K app you ain't gonna need it, so you're forced to really pare down your app to make it just do what it's meant to do. It also shouldn't take long to write a 5K app, so it's a great way to try some experimental ideas out.

The Rules

  • 5K is the total size of the app as distributed:
    • You may zip/tar etc to decrease the size of the distributed app.
    • Obfuscators etc are allowed and may be needed to help reduce compiled code size.
  • Network access is allowed, but:
    • You will not load more executable code or resources over the network.
    • You must disclose all net access.
    • Your app should not break when no network access is available.
    • You may only access servers you do not run (no writing a webapp that does all the work for your 5K app).
    • Preferably all network access should use standard APIs (e.g. Flickr or Twitter APIs), though this is not a requirement.
  • All resources (images etc) count towards the 5K limit.
  • You may specify certain (reasonable) installation requirements (e.g. Java/.Net/Firefox/Greasemonkey)
  • Browser-based apps must work in at least one major browser - cross-browser compatibility is a bonus not a requirement.


The winner will be determined by a vote (possibly a preference vote) at the event.

Ideally the applications will be made publicly available prior to the event for everyone to see. Applications will also be demoed at the event, so everyone gets a chance to see them in action before voting.

Voters should judge applications based on their:

  • Utility/Fun - does the app do something useful or if it's a game is it good fun?
  • Awesomeness - does the app achieve something technically impressive within the 5K budget?

Applications will be reviewed before hand to ensure they meet the rules.

Applications that are slightly (e.g. a few bytes) over the 5K budget may be allowed, but that will be at the discretion of the organisers. We might even arrange some sort of scoring system whereby you lose points for being over budget - so there would be a trade-off between adding a new feature that may get more votes and going over budget.


That all depends on how much interest there is. Once we have enough entrants we'll organise a £5app meet to do the judging.

See Also


  • 5KTwit - example app by John
  • 5KTODO - another example by John (Javascript with local storage of TODO items)


The rules are open for amendment/discussion.

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