Engineers at LINE Fukuoka Participated in a Virtual Hackathon

At the LINE Fukuoka development department, 80 engineers participated in a remote ideathon and hackathon for two weeks. I’ll introduce how we prepared the event remotely and the deliverables that were presented at the event.

Engineers at LINE Fukuoka participate in a hackathon every year (except last year when we couldn’t run the event). This year the event was held remotely to prevent the spread of COVID-19.


In previous years, the general flow of the event was as follows:

Run an ideathon -> participants perform an elevator pitch -> participants finalize their teams -> run the hackathon -> participants give presentations.

There was a phase before the hackathon where participants brainstormed ideas together and pitched their ideas to others in order to gather teammates.

There are more than 80 engineers at LINE Fukuoka, so participants like to form small groups based on similar interests and move between these groups to brainstorm ideas. However, as you may have guessed, it’s hard to do this remotely.

Therefore, different topics that the participants were likely to come up with were listed into different categories. Zoom rooms and Box notes (an online note pad that facilitates collaborative editing) were then created for each category and their links were pasted onto a Confluence page.

The online note pad made it possible for participants to keep track of what others have said at a Zoom meeting.

The online note pad was useful for remote work because it helped them share and discuss ideas during the two-week long ideathon.

At the end of the second ideathon session, participants used SpatialChat for online drinks/casual brainstorming, which also helped them generate innovative ideas.

In previous years, participants had to have at least two people in their team, but since it’s hard to find teammates when working remotely, one-person teams were allowed this year. Nevertheless, 18 out of 32 participating teams had multiple team members.

In addition, all the participants had to give a presentation, which took up almost a whole day. However, that was optional this year as they could take part in the hackathon to simply study about their chosen topic, and presenting in the form of text, such as a blog, were suitable for some projects.

Day of Hackathon

We didn’t think all participants should get together in the office on the day of the hackathon, but allowed them to use the office if they wanted (a survey asking whether they’ll come to the office was conducted beforehand).

Of course, many teams participated remotely, and a lot of them created their own Slack channel and stayed connected to each other via Zoom for the whole day.

Project Presentations

The LINE Fukuoka development department has a diverse group of engineers with different nationalities, and the main languages used are Japanese and English. Engineers can use either language for their presentation, but for those who are not so good at speaking either languages, they can ask an interpreter to simultaneously interpret their presentation. However, unlike the usual development projects, the interpreter may not know the context or jargon. Therefore, the interpreter prepares to interpret for the presentations by reading the presentation materials and asking questions beforehand. On the day of the event, the interpreter joins each team’s Slack channel to receive updated information.


Visualization of CO2 Concentration in the Air

In the IoT category (which is a field we rarely get to work on), three teams developed systems that measure, visualize, and notify CO2 concentration in the air. Each team had different and interesting ways of developing the system. One implemented an orthodox method of combining an ESP32 module-installed Arduino with a CO2 sensor, and another used a Smart Citizen Kit to switch data from multiple devices to visualize CO2 concentration. The third team already had a monitor-equipped CO2 sensor that did not connect to the internet, so they digitized it using image recognition to process the monitor screen.

AR Copy and Paste

One team developed a smartphone app which can copy an object that was captured on camera and reposition it in the same photo. The team used interesting technology, including a machine learning platform called Tensorflow Lite to detect and copy objects, and AR core to detect the ground and paste objects.

Laser Harp

Motivated to make a laser harp, an instrument played by Susumu Hirasawa, a Japanese musician, one team built a laser harp using LEGO, lasers, sensors and an Arduino.

Watch our engineers play the harp in the video below.

Visualization of Degree of Collaboration with Colleagues Using Slack (Slack Chat Map)

Our company conducts peer reviews once every six months, but it’s hard to remember who you’ve worked with over those months. To overcome this issue, one team created social graphs based on conversations with their colleagues via Slack. This helps visualize workplace relationships easily as Slack and other chat tools are being used more often to communicate with colleagues due to the shift to remote work.

Creating a “Map” of Must-Read Books

One team of engineers, who love to read books, created an app that recommends books in the form of a map. Recommendations are based on information of books that they gained from the internet, and the idea of a map was inspired by the reading map of Iwanami Shoten (link in Japanese only), a publishing house in Japan.

Not only did they try out Neo4J, a graph database platform, they managed to create two apps: one that opens the map using WebView , as well as an iOS app that can search for books.


At LINE, engineers use the company’s proprietary deployment tool called PMC for many of the company’s products. PMC has a UI that works on browsers, but since it’s an old tool, first-time users find it unwieldy and users want to view the deploy log on chat tools. Therefore, one participant created a tool that can deploy using a Slack bot called PMC BOT. This was in fact his second project this year—during the hackathon, he took the opportunity to implement a rollback feature that he always wanted to implement to this tool. The project was interesting as well because the feature was implemented using a state machine.

Custom Tag Search for LINE Stickers

A feature called “tag search” for stickers was recently added to the LINE app. Currently, you can choose from a fixed set of frequently used words such as “okay” or “thanks,” but one team made these tags customizable. A team member, also a developer of LINE’s client application, wanted to add this feature to the product he was developing, so he made a prototype of the feature during the hackathon. He said that he was going to share this prototype with his client application project team members. I believe that the best part of participating in LINE’s hackathon is to be able to implement your original features in the LINE app.

There were many other brilliant ideas. There were more than 80 people watching the presentations, so some of them were probably non-engineers but took their time to visit our event.

Reflection of Event

Some of the participants felt that it would’ve been more enjoyable if the hackathon was held offline, but overall the feedback was positive:

  • It was fun to be able to build devices that can actually move.
  • Using work hours to focus on making something was a lot of fun. I also got to meet and collaborate with interesting people.
  • Studying a specific topic for the hackathon project was relaxing.
  • It was awesome to have the opportunity to make something based on our own interests and ideas.
  • I got the time to focus on a research topic that I’ve been wishing to work on.
  • It was interesting to research/create something that is different to my usual work, and the projects were diverse.
  • However, it was a pity that we couldn’t see how the other teams worked on their projects.
  • It was great to take a break from work and write lots of code! However, it was a bit disappointing that we couldn’t physically get together because of COVID-19. It would’ve been livelier that way and we could’ve celebrated at the end.

Many participants enjoyed using devices, like sensors, that they seldom use for work, and do other things that interests them but don’t get to do everyday. They also enjoyed collaborating with people that they don’t normally interact with. Everyone enjoyed the event, so I’m very glad that we were able to run the hackathon, even though we had to run it virtually this year. Going forward, we’ll continue to run a hackathon every year at LINE.