Behind the scenes: Chaos Communication Congress presale

A scanner, watching you. Beep!

A scanner, watching you. Beep!

Have you ever tried to solve a problem that is completely, utterly, ridiculously impossible?

Welcome to our world! We’re the team running the Chaos Communication Congress ticket sales, and we want to follow the good example set by the content teams, and explain a bit of our work.

Now, from the outside, our problems may not seem all that impossible. In fact, you may think we have very little problems indeed: We run the presale of a conference that is notoriously sold out, and that’s generally what you want when you organise an event, right? Well, yes and no. Our primary goal is neither to sell every last ticket nor to increase our prices knowing that we’ll be sold out anyways – our goal is to invite participants in a way that is consistent with the values represented by our event and our community.

The Chaos Communication Congress is first and foremost a community event. Its unique beauty as well as its unique challenges originate in the fact that we are a huge distributed anarchical group of unpaid volunteers who manage to build an event for over 16000 people, every year. To make matters even harder, our completely self-organised decentralised structures work without a single point of authority. If you think that this cannot possibly work, you’re not alone: It’s hard to explain to people on the outside, and when we try, we’re usually met with a blank stare or disbelief.

None of our Congresses would work without two overlapping, vaguely-defined groups of people: The teams who spend inordinate amounts of time before and during the event organising and working, and the local groups and hackerspaces who do a lot of great work throughout the year that has nothing to do with Congress at all. Without the people tinkering in hackerspaces, running smaller events, creating awesome new hacks, educating people, visiting schools to talk to kids, running workshops, discussing positions and organising protests … we wouldn’t have the vibrant community that turns Congress into an event without its like.

Consequently one of our goals is to make sure that both organising teams and active people from other groups have a chance of attending Congress – but at the same time, we don’t want to limit ourselves completely to people who have already done their part. We’d be completely caught in our own filter bubble, and therefore we also want Congress to be accessible to new people.

This is a tough one. Fundamentally, there cannot be a perfect solution: We sell less tickets than people want to buy and our community grows larger every year. Period. Which means that some people will not be able to buy a ticket, no matter how much they want to, or how good a fit they’d be for the event.

Possible solutions to this are manifold: We could turn the event into a private event only for people who are already part of the community. We could just increase our ticket prices until the demand balances with the available tickets. We could go by “seniority” within the community, or by capability by introducing artificial technical barriers (a quiz? a hidden ticket sales server via ssh?). We could insist on a personal recommendation from a trusted person, or expand this into a dystopian voting system where only people with a sufficient number of votes get in. We could set certain quotas by demographics and then distribute tickets according to age, gender, social status, income, text editor, or hair color. We could make ticket sales entirely random (more on that later), or just sell as many tickets as we can, ignoring the problems that start when you let a community grow faster than it can support itself. But we don’t think any of these are a good idea.

Our current solution works like this: We don’t sell all tickets to the general public. Instead, we start by handing vouchers to all dedicated volunteers from last year’s Congress, so they can buy a ticket for this year if they want to. Simultaneously, we also give vouchers to local groups, like hackerspaces, and some activist groups. Their vouchers spawn new ones once they have been used, so that these groups can distribute the vouchers among themselves. Roughly half of our tickets are sold to somebody with a voucher. (The truth is slightly more complex, and if you like reading rule books, you can read up on them in our documentation).

Once the tickets reserved for the active community are used up, we turn to the remaining tickets, and sell those in three open presale days. They are notoriously gone within minutes, if not seconds. The technical challenges of serving several thousand requests per second in an attempt to sell tickets is interesting in its own right, but we’ll leave that as an exercise for the reader for another post.

Obviously, this is not an ideal system and it fails in a variety of interesting ways. For example, local groups may have questionable priorities when distributing their vouchers. People may have broken mailservers and will never receive their voucher. People who use a reproducing voucher may take a long time to pay, blocking people who wait for their replicated voucher. If you have very slow internet or slow reflexes or are not aware of the urgency, buying a ticket in the open presale is nearly impossible. It’s frankly heartbreaking to talk to people who will not be able to attend Congress.

And that’s a significant part of what we do: As the presale team, we answer all emails sent to our address, usually within a day. Last year, we received a total of 2690 emails and sent 1764 in 1623 threads, so roughly 10% of attendees contacted us. This excludes spam, but includes bounces – because we look at those, and try to figure out if there was a typo in the mail address, or if we know somebody who knows this person and can get in touch with them. If you write us, you don’t receive a canned response either – every response is more-or-less lovingly created by one of the four of us.

Other than that, what do we do? We usually deal with requests for vouchers from various groups, which has served to expand our knowledge of geography. Occasionally we help settle local conflicts when one group won’t talk to the other – it’s the Chaos *Communication* Congress, after all. To keep our workload at an unreasonable-but-possible level, we try to send vouchers to only one place per city, region, or thematic community. We also help people who found one of several tempting ways to make errors in their ordering process (typos in email addresses or payment references are the favourite). We help with payment difficulties and supply people with documentation for their visa application. We prepare the on-site ticket checkin – scanning this many tickets is a challenge of its own, of which we have written more here. We also administrate the servers, which is especially challenging when preparing for the open presale days, which can see request spikes of more than 16.000 requests per second, and requires a bit of careful planning. Before the presale starts, we negotiate conditions with the local public transport company, and help determine the ticket prices and what average ticket price we need to reach – you can always see the chart of average ticket prices here.

We’re also constantly looking for ways to improve the presale. Every year we make some minor changes and adjustments that go mostly unnoticed (which is good!). We have experimented with simulating parts of the presale, to get a feeling for the results that we would introduce with different replication rates, spawn times, and distribution mechanisms. This also involves talking to lots of people to help us balance the needs of different groups: Within Germany and from abroad, from within the community and newcomers, marginalised groups and people who have been around for most of CCC’s history, people who cannot participate in a regular presale for health reasons, and so on.

We’re nearly always happy to discuss your ideas, and we only have two requests if you want to let us know what you think: First off, please assume that we’re trying our best – because we are, and people who send us very angry mails about our malice or our incompetence just make us sad, but won’t improve the presale process.

Secondly: Please do not suggest that we try a lottery. We know, it’s tempting – it’s the first solution that springs to mind to solve this problem, but it’s also just not going to happen. The short explanation is: Any lottery that can’t be cheated easily will require us to check people’s IDs at the entrance, and that’s not something we are willing to do – both due to the logistical challenge of slowing down the entire check-in process extremely, and because we follow the principles of minimal data retention. We don’t care about your official names, we don’t want to check your ID, and we run screaming when thinking about the implications of this level of data aggregation.

A last note: While we have seen a lot of bitter, or angry, and occasionally hateful messages, we have also seen plenty of support, humour, and good-natured snark, which makes the whole effort more than worth it. Thank you!

34C3 Presale

[English version below.]

Es ist wieder soweit – der Vorverkauf für den diesjährigen Chaos Communication Congress beginnt!

Wie schon im letzten Jahr läuft der Vorverkauf für den diesjährigen Congress in zwei Phasen ab. In der ersten Phase möchten wir den aktiven Kern unserer Community einladen, am Vorverkauf teilzunehmen: Diese Phase beginnt heute und endet, sobald das Kontingent für diese Phase erschöpft ist, spätestens jedoch am 15.10.2017.

In der zweiten Phase verkaufen wir zu mehreren Terminen Tickets frei nach Reihenfolge der Bestellungen. Die Termine für den freien Verkauf werden wir hier mindestens zwei Wochen vorab bekanntgeben.

Wir werden alle verfügbaren Tickets in den Vorverkauf geben. Falls am Ende der zweiten Vorverkaufsphase noch Tickets verfügbar sind, werden diese an der Abendkasse verkauft.
Ob dies der Fall sein wird, kündigen wir an dieser Stelle bis zum 20.12.2017 an.

Der neue Veranstaltungsort bringt eine Reihe finanzieller Unwägbarkeiten mit sich – nach mehreren Konsultationen verschiedener Glaskugeln haben wir den notwendigen durchschnittlichen Ticketpreis berechnet. Auf findet ihr Details und einen Graphen, der den Durchschnittspreis der bisher verkauften Tickets zeigt.
Bitte unterstützt uns, wenn ihr könnt.

Die Vorverkaufsphasen sind unter im Detail beschrieben. Wenn ihr noch Fragen zum Vorverkauf habt, schaut bitte in unsere FAQ unter oder schickt uns eine E-Mail an

Wir sehen uns im Dezember!
Euer 34C3-Presale-Team

It’s that time of the year again – we’re opening the presale for this year’s Chaos Communication Congress!

Again, there will be two phases, with the first one starting today.
During the first phase, we’d like to invite the core of our community to participate in the presale.
It will end as soon as no more tickets are left in the pool for this phase, but by 2017-10-15 at the latest.

During the second phase we’ll open the presale to everybody on a number of pre-announced time slots. We’ll announce these open presale dates at least two weeks ahead of time on this site.

We’ll offer all tickets for presale. Im case they don’t sell out, we’ll offer the rest on-site in Leipzig. We’ll tell you until 2017-12-20 whether this is going to be the case or not.

Planning an event of this scale at a new location comes with many uncertainties. As best as we could, we have calculated the average price necessary to make 34C3 pay for itself – you’ll find details and a chart plotting the average ticket price of currently sold tickets at
If you are able to support us, please do!

You can find a more detailed explanation of the presale phases and the voucher system at If you have any questions, please refer to the FAQ at or contact us at

See you in December!
The 34C3 presale team

Easterhegg 2017 – Vorerst Ausverkauft

vorerst_ausverkauftDie Easterhegg 2017 ist leider vorerst ausverkauft. Wir hatten ein Kontingent von 500 Tickets, die ihr uns, in nur neun Tagen, buchstäblich aus den Händen gerissen habt. In voraussichtlich zwei Wochen wird es eine zweite Runde geben, bei der die Rückläufer und nicht bezahlten Tickets wieder in den Vorverkauf gehen.

Daher auch die große Bitte an alle die ihr Ticket noch nicht bezahlt haben: Zahle dein Ticket bitte bis zum 3.2. damit wir dann in der Woche ab dem 6. Februar die restlichen Tickets in den Vorverkauf geben können. Solltest du bis dahin – aus Gründen – nicht in der Lage sein dein Ticket zu bezahlen, schreibe bitte eine kurze Mail (ohne Begründung, der Wunsch ist ausreichend) an damit wir dein Ticket nicht wieder in den Verkauf geben.

Weiterhin freut sich natürlich auch unser Frab weiterhin über Einreichungen. Wenn du schon immer Mal einen spannenden Workshop anbieten oder einen kurzweiligen Vortrag halten wolltest, dann ist das deine Chance!

Easterhegg 2017 – Es gibt Tickets

Es ist soweit, es gibt Tickets für die Easterhegg 2017 in Mühlheim / Main. Der Vorverkauf findet sich unter:

Das Ticket für das Wochenende kostet 42 Euro. Wenn du freiwillig mehr bezahlen möchtest, freuen wir uns, wenn du ein Supporter-Ticket nimmst. Damit gibst du Leuten, die sich den Eintritt nicht leisten können, die Chance an der Veranstaltung teil zu haben. Weiterhin gibt es die Möglichkeit auf dem Gelände mit einem Wohnwagen zu campen. Leider ist der Platz sehr grob geschottert, so dass wir vom Campen mit einem Zelt auf dem Platz abraten müssen. Das Campingticket kostet 23€ für die Dauer der Veranstaltung (1 Fahrzeug & maximal vier intergalaktische Lebensformen. Es beinhaltet Strom und bedingt Wasser (kein Abwasser!), sowie warme Duschen im Gebäude. Neben den Tickets gibt es auch auch T-Shirts, Hoodies und Zipper im Shop sowie zusätzliche Tassen.

Camp 2015 Ticket Shop is open now!

We all are very much looking forward to Camp 2015 – the new location makes things very exciting but such a new location also makes it very costly: We’ll need to get at least 950.000 EUR from ticket sales, which brings us down to an average ticket price of ~212 EUR.

When we moved the Congress to the new venue in 2012 we have been facing the same issue, remember?
Back then, we didn’t want to raise the price above 100 EUR and right now we don’t want to go above 200 EUR: We leave this, again, up to everyone of you to contribute as much as you can afford to – to make the Camp affordable for everyone in sum.

You can get:

  • Standard tickets for 220 EUR,
  • Supporter tickets for 240, 260, 280 and 300 EUR,
  • Business tickets for 450, 600 and 750 EUR,
  • Up-and-coming tickets for 50 EUR.
  • If you are on a low budget, there is the option to buy a ticket for 200 or even 180.
  • As usual there is also the friends request available, so that everybody is able to attend.

We provide you in the ticket system a graph that shows the average ticket price and how far away we are from the goal of 950.000 EUR. Please help us to create a nice graph! :)


Please be aware that there will be no ticket sale on site! So go ahead and get your ticket right now: – if you have further questions please refer to our wikipage.

Shame on us, we forgot the Up-and-coming tickets for our young generation! This is fixed now.

If you are under 12 you get in for free! Between the age of 12 and 18 you are eligible for an Up-and-coming ticket for 50 EUR. That means, you must convince us to be born before August 13th 1997. Please bring a (sufficiently convincing fake of a) document / photo ID stating your age.

easterhegg 2015 presale eröffnet

Wie bereits auf easterhegg 2015 (Pr3zale is open.) zu lesen war: Es können jetzt Tickets für #eh15 vorbestellt werden.

In unserem eigens dafür gebauten Pr3zale könnt ihr euch die begehrten Tickets vorbestellen.
Und nicht nur das: Was wäre das EH15 für eine Hackerveranstaltung, wenn es nicht auch T-Shirts und Tassen geben würde!

Außerdem läuft auch der CfP noch. ;-)

easterhegg: Ende des Presales naht


Hallo zusammen! Der Presale zum Easterhegg ist fast vorüber. Konkret bedeutet das, es gibt von nun an keine Extratassen und Zipper-Hoodies mehr.

Tickets und T-Shirts bekommt ihr noch eine weitere Woche lang. Danach wird der Presale endgültig geschlossen und Tickets sind nurnoch über die Abendkasse erhältlich. Abendkassentickets enthalten selbstverständlich auch eine Tasse. T-Shirts halten wir in begrenztem Umfang auch vor Ort noch vor.

Falls ihr euch ein Ticket nicht leisten könnt, meldet euch bitte bei der Orga, wir finden eine Lösung.

Falls ihr euch mehr leisten könnt, klickt bitte eine der Sponsorenstufen.

DEADLINE PRESALE: Mittwoch, 9. April 2014


Wir dressieren noch den schwäbischen Amtsschimmel. Dieser wiehert aktuell, dass wir nicht cool genug für Ausnahmeregeln am Karfreitag sind. Wir arbeiten an kreativen Hacks und werden in Kürze berichten.


Die Hausverwaltung benötigt zur erfolgreichen Durchführung der diesjährigen kEHrwoche noch viele, fleißige Engel (der Terminus Technicus ist “kEHrtaker”). Bitte tragt euch unbedingt im ein, und vergesst nicht eure T-Shirt Größe anzugeben, damit wir entsprechend planen können.

Bitte beachtet, dass wir eure Anmeldung bis spätestens 09. April (kommenden Mittwoche!) brauchen, um die T-Shirts entsprechend bestellen zu können.

Eventphone / DECT

Zur Sorge um besseren Kommunikation bei kEHrarbeiten konnten wir das POC begeistern. Für euch bedeutet das, ihr könnt wie gewohnt eure DECT Telefone mitbringen. Die Anmeldung auf wird in Kürze freigeschalten.

Vergünstigte Nahverkehrstickets

Die Stuttgart Marketing GmbH bietet für Übernachtungsgäste und/oder Kongressbesucher ein 3-Tage Ticket an (4 Tage gibt’s leider nicht). Das bekommt ihr gegen Vorlage eures ausgedruckten EH Tickets oder einer Hotelbuchung an einem der beiden i-Punkte der Tourismusinformation. i-Punkte gibt es direkt links im ersten Gebäude der Königstraße gegenüber vom Hauptbahnhof oder für unsere fliegenden Mithacker in Terminal 3 des Flughafen Stuttgart.

Achtung: Ihr braucht das netzweite Ticket für 15 €, da die Location knapp in Zone 20 und damit außerhalb der Mittelzone 10 liegt.

Mehr Informationen unter


Falls ihr für euer Projekt Spezialwünsche wie z.B. mehr Strom als ein paar Laptops, meldet euch bitte ASAP beim Orga Team.


Der Fahrplan ist – wie üblich – noch nicht ganz rund. Der Inhalt stimmt prinzipiell, die Zeiten noch nicht ganz.

Bei Fragen einfach eine kurze Mail an
Wir sehen uns zur Kehrwoche in Stuttgart! Mit freundlichen Grüßen, die Hausverwaltung.