24-26 September 2025, CityCube Berlin. Three days at droidcon Berlin, the biggest Android event in Europe, and at Fluttercon Europe, the biggest Flutter and Dart gathering on the continent — two conferences held in the same building, on the same days, with a single badge that opens both.

I did not go only as an attendee: on the third morning I was on the droidcon stage, co-hosting the talk Inside Android: Context, Binder IPC, Zygote with my Deloitte Digital colleague Ioannis Anifantakis. Below is what those three days looked like — the talk, the two show floors, and the city in between.

• dcbln25
• ftcon25eu
• Android
• Flutter
• Kotlin
• Dart
• Binder IPC
• Zygote
• Berlin

From a room in Berlin to two conferences in one building

droidcon started in Berlin as a grassroots meet-up of Android developers, and sixteen editions later it is back in the same city — this time with a Flutter conference attached to it.

1. 2009 Berlin The first droidcon, a couple of hundred developers
2. 2022 London One of the largest editions so far, 1,400+ attendees
3. 2023 Berlin The first Fluttercon, co-located with droidcon: 2,000+ together
4. 2025 Berlin, CityCube 16th edition — where #dcbln25 and #ftcon25eu were held

Getting there

840 km from Via Santa Sofia 28 in Milano to Berlin, then an S-Bahn ride across the city every morning — the Fernsehturm showing up in the window somewhere around Alexanderplatz — and out at Messe Berlin, where the CityCube sits at the end of a long ramp.

The Fernsehturm from the S-Bahn, every morning

The commute, twice a day

The S-Bahn out to Messe Berlin

Messe Berlin, the walk in

"Welcome to droidcon Berlin"

...and, on the next door, "Welcome to Fluttercon"

Inside the CityCube: registration, and then pick a side

One badge, two conferences

The two events are co-located: one ticket registers you for both, and for three days the CityCube is split down the middle. On one side the Android tracks — Compose, Kotlin, architecture, AI on device, security. On the other the Flutter and Dart ones. Between the two, a shared expo floor, a shared lunch queue, and a lot of people wandering across the line because the interesting talk happened to be on the other side.

droidcon Berlin brought 1,300+ developers from more than 30 countries and 90+ talks and workshops across five tracks, with Google, JetBrains, Qualcomm, Gradle and Uber on the floor; Fluttercon added 1,000+ Flutter developers and 75+ tech talks, with keynotes from Kevin Moore ("Let's go far with Flutter") and Eric Seidel ("The Future is Written in Dart").

One badge, both lanyards

The speaker lounge, shared between the two

"Together we are droidcon"

"We are fluttering together"

24-26 September, #ftcon25eu

Day one, before the doors opened

Long benches on the floor, laptops open between talks

The lounge, where half the conference actually happens

Inside Android: Context, Binder IPC, Zygote

Friday morning, droidcon stage. Inside Android: Context, Binder IPC, Zygote, co-hosted with Ioannis Anifantakis — a talk about the parts of Android nobody puts in a getting-started guide: what the Context actually is, how a process gets born, and why any of it matters when you are writing an app.

The first half is the Context as the real handle to the operating system, and the Manifest as the contract the system reads before your code ever runs. The second half is the one I took: Zygote, the process every Android app is forked from. Zygote boots once, loads the framework classes and the heap, and then every app launch is a fork of that already-warm process — a photocopier rather than a new machine — with copy-on-write memory shared between all of them. From Android 10 on, USAP (Unspecialized App Process) keeps a small pool of pre-forked, neutral processes waiting, so the fork does not even have to happen at tap time.

Ioannis opens with the Context

The handover, halfway through

"Every Android app is the child of a single parent cell"

My half: how a process gets born

Mid-Zygote

The process photocopier: fork, don't rebuild

Explaining copy-on-write to a room at ten in the morning

Zygote, the parent cell

Pre-Android 10 vs Android 10+: USAP

A pool of unspecialized processes, waiting for a job

The minions, at full stage width

Two of us, one Context

"Meet the speakers", right after the talk

Fluttercon: Dash everywhere

The Flutter half of the building is impossible to mistake for anything else: a three-metre inflatable Dash in the middle of the floor, the same bird on every screen, and rooms full of people arguing about state management. The talks I sat through were the ones about pushing Flutter and Dart outside the phone: Jaspr, a web framework for Dart developers that renders real HTML and CSS instead of a canvas, and a deep dive on Flutter embedding — how to drop a Flutter view inside an app you did not write in Flutter.

Dash, three metres of hummingbird

A full room, Fluttercon side

Jaspr: "the framework for Dart developers"

Flutter and Jaspr, side by side

Every talk opens with a "That's me!" slide

From the back of the room

Ten minutes before, the room fills from the back

Flutter embedded inside somebody else's app

Every talk ends with a QR code

"Enjoy lunch in Hall B"

Flutter Community, Codemagic and friends

Flutter Berlin, the local meetup

The expo floor

One hall, both communities: an inflatable green Android next to an air hockey table, a "Dependency Den" room, pallets and cushions in place of chairs, and the usual line of stands giving away a Meta Quest to whoever scans the QR code.

Air hockey, under an inflatable Android

"Dependency Den", the best room name of the fair

Pallets, cushions and palms

A demo, between two talks

Scan the QR code, win a Meta Quest 3

The floor, between sessions

BREAK: the most-watched slide of any conference

The main hall between two sessions

Between talks

The part of a conference that never makes it into the agenda: the terrace outside the halls between sessions, a beer at four in the afternoon because the schedule said "networking", a laminated card on the bar with the WiFi password on it, and a German bakery on the way in every morning.

Outside the halls, badge still on

Day one, badges collected

"Networking", officially

The most photographed object of any conference

The bakery on the way in

Breakfast before the first session

Two Maß at the Hofbräu, end of day one

Schweinshaxe, served with a knife in it

Kebab: Berlin runs on this

Dinner, day three

"Checkpoint Kebap", inevitably

Lunch, day four

Berlin

Then Berlin, which is a very hard city to visit casually. What is left of the Wall runs through the middle of it — 1.3 km of it painted at the East Side Gallery, a bare stretch behind the Topography of Terror, a line of cobbles across the asphalt where there is nothing left at all. Checkpoint Charlie is now a photo op between a KFC and a souvenir shop, with the original sign still telling you that you are leaving the American sector. And the Memorial to the Murdered Jews of Europe is 2,711 concrete slabs a few hundred metres from the Brandenburg Gate: you walk in at street level and the ground drops away under you until the city disappears.

Brandenburger Tor, blue hour

And the same gate on a Saturday morning

2,711 slabs, and the ground drops away

Looking out, where the slabs drop back to nothing

The same field, the morning after

From the edge, where the slabs are still ankle-high

"You are leaving the American sector"

The other face of it, in Russian and German

Checkpoint Charlie, from the floor above

The guard house, rebuilt where the real one stood

Friedrichstraße, the crossing point

At the museum: the cars people escaped in

East Side Gallery, 1.3 km of it still standing

The sign, painted on the wall itself

Painted, repainted, tagged over

One of the 1990 originals

And one of the stranger ones

Colour on concrete

The far end, all tags

The Spree, on the other side of it

East Side Mall: the name outlived the border

Breakfast, eaten against the Wall

The tower, over the death strip

Under the arches, back towards the middle

"My God, Help Me to Survive This Deadly Love"

The compulsory photo

The unpainted side, under a Mercedes star

The rest of the city is easier: Museum Island and the Berliner Dom on the Spree, the Reichstag and its glass dome, the Siegessäule at the end of a two-kilometre avenue through the Tiergarten, and the view from the Fernsehturm — 203 metres up, one full turn of the observation deck, an espresso martini, and the sun going down over the whole thing.

Berliner Dom, from the Spree

The same, at night, with the tower behind

Neptunbrunnen

Reichstag

The Siegessäule at the end of the avenue

Goldelse, 67 metres up

Schloss Bellevue, across the Tiergarten

The Sony Center roof, from Potsdamer Platz

The skyline, and the tower again

Alexanderplatz, looking up

The same view, twelve hours later

Alexanderplatz at midnight, all of it to yourself

It is visible from most of the city, which is the point

Nord–Süd, a line that used to stop at the border

A Trabant, parked at Potsdamer Platz

Glass roof, on the way out

The Spree from 203 metres

One turn of the deck takes about half an hour

Sunset, from the top

Urban Nation: street art, indoors

Where the paint does not stop at the Wall

Walk west along the Spree from the East Side Gallery and the painting simply carries on, off the Wall and onto whatever is standing. Holzmarkt is the clearest case: a stretch of riverbank rebuilt as a village of timber shacks, bars and clubs, every surface of it decorated. It looks nothing like the government quarter forty minutes away.

Holzmarkt, built out of timber and paint

Every surface, including the ones nobody asked about

Eleven in the morning, still recovering from Friday

"Love letter to the city"

The same building, all the way up

And, by pure luck, Oktoberfest

Nobody plans this: the last weekend of September, Alexanderplatz is taken over by a full Oktoberfest — beer tents, Lederhosen, a brass band on a stage under the Fernsehturm and long blue-and-white tables in the middle of a square that is otherwise all concrete and trams. We came down from the tower and walked straight into it.

The band, under the tower

Long tables, on a Saturday afternoon

Spotted from the tower, an hour earlier

Lederhosen, in Berlin

A Maß, with the Fernsehturm behind it

Bratwurst, longer than the bread

The same square after dark

A carousel under the Fernsehturm

A Brezel, held up against the Fernsehturm

Everybody sits with everybody

Munchies: a smash burger, not a Bratwurst

Blue-and-white stalls, all the way to the tower

The other compulsory photo

And again, because it was that good

The Fernsehturm's shadow, thrown across the Park Inn

Flying home

Sunday evening at Brandenburg, on the tarmac, with the sun going down behind the wing. Four days, two conferences, one talk, and a phone full of photographs of the same tower from thirty different streets.

BER, waiting to board

From the steps

And from above, on the way back to Milano

Fluttercon Europe 2025 + droidcon Berlin 2025, CityCube Berlin, 24-26 September 2025.