Advent of Code 2025 in Kotlin: Puzzles, Prizes, and Community

Ksenia Shneyveys

Thank you to everyone who participated in Advent of Code 2025 in Kotlin! Once again, it was a joy to see so many of you sharing solutions, cheering each other on in Slack, and keeping the holiday coding spirit alive.

This year, we kicked things off with five days of livestreams on December 1–5, with Sebastian Aigner and fantastic guests solving puzzles live, discussing strategies, and showing off idiomatic Kotlin approaches.

If you missed the streams or want to revisit a clever trick, you can still catch up with the recordings:

Community

The Advent of Code puzzles remain available all year round, and so does the community energy. The #advent-of-code channel in the Kotlinlang Slack was once again full of:

• Creative Kotlin snippets
• Non-spoiler hints
• Lots of encouragement

Whether you took part in discussions every day or just lurked and learned, thank you for making the channel such a friendly, collaborative space.

Join the AoC channel in Slack

Winners

As in previous years, we invited you to solve Advent of Code puzzles in Kotlin, join our Kotlin leaderboards, and share your solutions on GitHub with the aoc-2025-in-kotlin topic for a chance to win special Kotlin prizes.

This year, we’re celebrating nine winners across three categories: Fastest to Solve, Random, and Community.

Fastest to Solve

These three contestants topped the combined Kotlin leaderboards, consistently solving the puzzles at impressive speed:

• Kroppeb
• AndrejStratmann
• 770grappenmaker
  

Congratulations on those lightning-fast stars and Kotlin-powered solutions!

Random winners

To give everyone a chance regardless of speed, we also randomly selected three prize winners from all the participants:

• lbcp
• FelixDombek
• bjdupuis

If you see your name here, keep an eye on your inbox. We’ll be in touch about your prize soon.

Community winners

Finally, Advent of Code in Kotlin wouldn’t be the same without the people who answer questions, share insights and alternative solutions, help newcomers get started, and keep the #advent-of-code channel buzzing throughout December.

This year, we’d like to give a special shout-out to these three community stars:

• jakubgwozdz
• bj0
• ephemient
  

Thank you for your team spirit in the Kotlin community!

Keep learning and solving

Advent of Code might be over for this year, but the puzzles and the learning opportunities remain. If you’d like to keep sharpening your skills and prepare for future events, here are some resources:

• Advent of Code 2025 in Kotlin YouTube playlist.
• Solutions to Advent of Code puzzles from previous years in idiomatic Kotlin.
• A tutorial on how to explore and solve programming puzzles using Kotlin Notebooks.

We want to say a huge thank-you, as always, to Eric Wastl and the Advent of Code team for creating such a beloved set of puzzles year after year.

Let’s keep exploring Kotlin, solving algorithmic challenges, and supporting each other. We hope to see you for the next Advent of Code in Kotlin! 🎄

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