Organizing a Successful Internal Hackathon: Mercari Hack Fest Spring 2023

Hello! I am afroscript from the Mercari Engineering Office.

Since September 2019, Mercari has been regularly organizing a biannual internal technology festival for its engineers called “Hack Fest.”

We are currently in the process of preparing the 7th Hack Fest, which will take place from April 19 to April 21, 2023.

We have been gradually updating the Hack Fest with each iteration. This time, I will introduce what this event entails at its current stage.

I hope that this article can serve as a useful reference for those who are currently organizing or planning similar internal events.

What is Hack Fest?

Hack Fest is a Technology Festival based on the concept of “Unlimited Hacktivity” aimed at fostering innovation that may not be possible within the constraints of “normal work”. By taking a break from routine tasks and dedicating a certain period of time to this event, engineers can concentrate on expanding their skills, or generating ideas that they may not have considered before.

Hack Fest Concept

As part of the preparations for the upcoming Hack Fest, we have decided to revamp the event"s logo and key visuals in order to infuse a more celebratory vibe. You may have noticed the thumbnail image of this article features the new key visual that our creative team has crafted to be both cute and stylish.

Why We Hold Hack Fest?

Hack Fest can be a powerful tool to foster creativity, encouraging teamwork and promoting out-of-the-box thinking for companies and organizations. The impact of such events can be seen in terms of three aspects: impact on the product, impact on the organization, and impact on the outside of the organization. We can identify five expected effects of holding Hack Fest by considering these three aspects.

  • 1.Impact on the Product : Creation of new ideas that innovate products
    • During Hack Fest, participants generate ideas can explore new possibilities that may not have been previously considered, and develop prototypes to bring these ideas to life.
  • 2-1 Impact on the organization : Increased motivation to work at Mercari
    • participants in Hack Fests can develop new skills and uncover untapped potential for the products they work on by examining ideas and outputs from diverse perspectives and collaborating with colleagues who have different areas of expertise. This exposure to different perspectives and experiences can help foster a culture of diversity and inclusivity within the company, leading to the growth of a talented and capable workforce. In addition, participating in Hack Fests offers employees the opportunity to connect with their colleagues and develop a deeper understanding of their work, which can serve as a motivation to work more effectively and efficiently at the company.
  • 2-2 Impact on the organization : Providing opportunities to improve skills
    • Hack Fest offers participants the chance to broaden their horizons by taking charge of projects from ideation to execution. This opportunity to take ownership of the entire process, from "what" needs to be done to "how" it should be accomplished, can help to foster an engineer-driven culture. In many organizations, product managers are responsible for determining "what" needs to be done, while engineers are responsible for figuring out "how" to accomplish it. By empowering engineers to take charge of both aspects, Hack Fest can help to break down silos and promote collaboration between different teams within the organization.
    • Participating in Hack Fest provides an opportunity for participants to strengthen and expand their expertise by exploring and experimenting with technologies and approaches that they may not use in their daily work. This can help to break down barriers between different areas of the organization and promote the idea that "everyone is a software engineer." By expanding their knowledge and skills, participants can also bring new insights and perspectives back to their daily work, driving innovation and improvement throughout the organization.
  • 2-3 Impact on the organization : Increased expectations for engineering possibilities
    • Participating in a Hack Fest can be a tremendous opportunity for companies to tap into the full potential of their engineers and foster a culture of innovation and excellence. By encouraging participants to explore new technologies, experiment with different approaches, and collaborate with colleagues across the organization, companies can help to build a foundation as a tech company and enhance their reputation as a leader in their field. In doing so, they can attract top talent, inspire their workforce, and drive growth and success in the long term.
  • 3.Impact on outside the organization : Contributing to branding as a tech company
    • Another important impact of Hack Fest is its potential to contribute to a company’s branding and reputation.

In addition, we believe that the five effects above will contribute to the long-term growth and success of both the products and companies.

Hack Fest Effects we expects

Flow of Hack Fest

The general flow of the event is team building -> exploring ideas -> entry -> development -> output. I will explain each stage in detail;

Outline of Hack Fest

Team Building

Participants can join Hack Fest both as individuals or teams

There are two ways of participating as a team. One way is to “build your own team”, and the other is to join a team by applying for a “shuffle team”

Participants can browse the Idea board (a worksheet where Hackfest participants write the detailed contents of their projects) to find and join existing teams in need of additional members.

Idea Board sample

Idea Board Example. In the “Recruiting Info” table located on the right side, people can easily check if a team is actively recruiting.

In addition, there is a system called "Shuffle Team", where 3 to 5 members are randomly selected to form a team and participate in Hack Fest. This system provides an opportunity to collaborate with individuals outside of your regular team, fostering knowledge exchange and creating a chance for teams to learn from one another. We introduced this system in our last event, with the aim of promoting cross-team collaboration and knowledge sharing.

Exploring ideas, entry

To participate in the Hack Fest, you need to fill out the idea board shown above. Each team is free to decide what to work on.

Each project should fall into one of these three categories: "things related to the product", "things related to refactoring and rearchitecturing of the system and development environment", and "things related to improving one"s own skills".

  • Things related to the product
    • Development of new features and services for Mercari and Merpay, as well as new apps/services related to Mercari that are not part of regular work. These projects offer a chance for innovative ideas to be explored and developed, and can potentially lead to new business opportunities for the company
  • Things related to refactoring and rearchitecturing of the system and development environment
    • Improvement/new development of internal tool and internal dashboard
    • Things that increase maintainability, developer experience, and productivity
    • Responding to security issues
    • Projects to reduce the complexity of the system
    • Remove unnecessary things (code, feature, repository, service,…)
    • Creating tools that promote refactoring
    • Creating guidelines to remove unnecessary things
    • Projects contributing to FinOps
  • Things related to improving one"s own skills
    • Learning new/unusually used technology and development using that technology

We collaborated with the Customer Success Team to create a dedicated Voice of Customer (VOC) page on our internal Hack Fest portal site. This page serves as a valuable resource for product-related inspiration and collects customer requests that are particularly relevant to Hack Fest. By incorporating customer feedback into the event, we aim to develop innovative solutions that meet the needs of our users and drive the continued growth of our platform.

VOC page for Hack Fest

We believe that Hack Fest can provide an opportunity to further enhance our customer-centric approach within the company, such as realizing customer requests that have not been addressed in our day-to-day operations, and finding solutions to customer challenges that have not yet been resolved. By incorporating these customer needs into the event, we aim to strengthen our commitment to customer satisfaction and drive innovation within our organization.

Development & output

Hack Fest is a 3-day event, with the first 2.5 days dedicated solely for development. During this period, participants are expected to produce tangible results in any format of their choosing. Examples include uploading code to GitHub, creating slides or documents to share with relevant stakeholders, or publishing content externally on the Engineering Blog. It is important to keep a record of the output in some way to ensure it is properly documented and can be leveraged for future projects.

Showcase Day

On the final day of the event, there is an opportunity for participants to showcase their output during an event called ”Showcase Day”, which takes place in the afternoon. This is a chance for teams to present their efforts to the wider group and share their accomplishments. It is a great way to celebrate the hard work put in by all participants and recognize their achievements during the event

Two types of presentation format:

  • Demo slot (Available up to 20 teams)
    • Participants will have 4 minutes to present
    • There will be 2 minutes Q&A time
    • This format should be used for projects with straightforward UI, projects with demos, and projects that require detailed explanation
  • Pitch slot (Available up to 10 teams)
    • Participants will have 1 minute to present
    • Presentation focusing on the purpose/summary/appeal points of the content we worked on.
    • Additionally, participants are required to submit some form of output (code, documentation, etc.) for evaluation based on its contents
    • For example, a presentation such as “I deleted unnecessary code for 100 lines!” would be suitable

Hack Fest Awards

Awards will be given on the Showcase day

The judges will examine the projects presented on the Showcase Day, and will select which ones will receive the Hack Fest awards. There are three basic award categories: Gold, Silver, and Bronze.

HACK Fest Award Criteria

Extra Award

In addition to the basic award categories, extra awards will be awarded in some special cases. For the upcoming Hack Fest #7, two extra awards will be given : FinOps Award and LLM Award.

FinOps Award is an award that recognizes an individual or team that promotes a cost-conscious culture and takes ownership of spending.

FinOps Award

In addition, the LLM Award aims to promote the use of LLM technology and further promote the understanding of LLM within the group.

LLM Award

Hack Fest KPIs

Until now, we have mainly relied on participant surveys to measure the effectiveness of our events. However, this time, we have reviewed our Key Performance Indicators (KPIs). It used to be difficult to accurately gauge the impact of the event because the number of responses to the survey were lower than what we were looking for.

To address this, we have added alternative metrics and are introducing our current KPIs, which are broadly classified into two types

KPIs that measure the excitement of the entire event

This KPI indicates the level of excitement generated by the event and how attractive it was to the attendees.

  • Number of entries to Hack Fest
    • At Hack Fest, filling out the Idea Board is considered an entry to the event. In other words, the number of entries equals the number of people who filled out the Idea Board
    • Participants can participate in the Hack Fest as an individual or as a team. For example, if a participant opts to participate as a team of 3, we will count it as 3 entries.
  • Number of participants on Showcase Day
    • This refers to the total number of participants at the results presentation event ”Showcase Day” which is held on the final day of Hack Fest

KPIs that align with the expected outcomes

This index is used to understand whether the "expected outcomes of Hack Fest" mentioned earlier are being achieved

  • 1 Impact on Products: Creation of new ideas that drive innovation in products.
    • Numbers of ideas on the idea board
    • (Long-term measurement) The numbers of ideas born at Hack Fest that are used in actual products/operations
  • 2-1 Impact inside the organization : Increased motivation to work at Mercari
    • (Survey-based measurement) Did participating in Hackfest increase your motivation to work at Mercari?
  • 2-2 Impact on the inside of the organization : Providing opportunities to improve skills
    • (Survey-based measurement) Did you learn new techniques that you don"t use in your daily work? Or did you have the opportunity to deepen a skill that you’re already somewhat familiar with?
    • (Survey-based measurement) Did you have the opportunity to work consistently from the "what" (what to make) to the "how" (how to make it)
  • 2-3 Impact on the inside of the organization : Increased expectations for engineering possibilities
    • Number of Showcase Day participants who are not Engineers or Product Managers (PdMs)
    • Number of participants at the After Party (where award announcements will be made) who are not Engineers or Product Managers (PdMs)
  • 3.Impact outside the organization : Contributing to branding as a tech company
    • Total number of unique users (UU) who viewed Hack Fest-related blog posts

We are still in the process of searching for suitable KPIs. Our plan is to measure the current KPIs and update them as needed, while striving to improve based on the results.


This article provides an overview of the current state of Hack Fest as of April 2023.

Hack Fest is a “Technology Festival” mainly for Engineers, Project Managers and Product Managers (PdM). However, excitement created by technology is not only felt by them but it also resounds to all Mercari employees.

Therefore, lately, my aim is to position Hack Fest as a festival that all employees can look forward to.
We worked with our in-house creative team to update the logo and key visuals of Hack Fest. We also added "improved expectations for engineering possibilities” to the expected effects of the event and focused on improving customer success. As part of this effort, we collaborated with the team to create a special VOC page and prepared FinOps Awards and LLM Awards. In addition to Mercari, Merpay members will also participate this time.

Hack Fest, which will be held for the 7th time, will be more exciting than ever.

(However, as the scale of the event grows and more people get involved, the excitement increases, but on the other hand, the complexity of the event also increases, making it difficult for participants to understand. The sense of balance has become more complicated.)

I"m very much looking forward to seeing all of the interesting results from Hack Fest.

I"m planning to write another article as an event report after the event, so please look forward to it as well!

Related Articles

If you want to know more about HACK WEEK, please refer to related past articles.

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