Introduction
I have been using an auction bot in my MMO guild for five years.
I built it around 2021 when Lineage2M was released to automate the distribution of boss drops for the guild. I also used it for HIT The World. Members place bids, and the bot divides the highest bid by the number of participants and manages the distribution. Tasks that would normally leave you staring at a spreadsheet if done manually were all handled by the bot.
It had been running constantly in my guild for five years. It was convenient, but it was strictly for my personal use.
The Reality of "Personal Use"
Even though I had spent five years developing it, the internals were a mess.
Guild names were hardcoded. Time zones were fixed. The only language supported was Japanese. There were no configuration files; if I wanted to change a value, I had to rewrite the source code directly.
When I wanted to use it on multiple servers, I would copy the entire container. I would set up another identical bot, change just the token, and run it. Multi-tenancy? What's that?
Billing systems were out of the question. There were no subscriptions, terms of service, or payment screens. I never intended to sell it to anyone. As long as it worked for me, that was enough.
Reasons for Deciding to turn it into a SaaS
I suddenly thought, "Couldn't I sell this bot?"
Many MMO guilds face the same problem. A rare boss drop appears. Who gets it? Let's decide with an auction. But managing an auction is a massive headache. Manually aggregating bids, calculating distribution amounts, and notifying everyone of the results. Many guilds want to do this, but it's impossible to handle manually.
However, turning a personal bot into a service requires massive refactoring: multi-tenancy, billing, an admin dashboard, multi-language support, and legal compliance. I had absolutely no motivation to do it by myself.
But we are now in the age of AI coding. For routine tasks without high uncertainty—tasks unlike research or experiments where you don't know what you'll find until you look—AI can finish them in a single sweep. That was my bet, so I decided to go for it.
Code Refactoring
Multi-tenancy, Stripe billing integration, OAuth2 authentication, web admin dashboard, and four-language support. The to-do list was long, but they were all routine tasks. The patterns were established, and there was official documentation. The goal was clear.
I defined the design policy and left the implementation to the AI. Individually, none of these tasks were difficult, but the volume was massive, and it was the kind of work I didn't want to do manually.
The initial plan Claude proposed was, "Split the 856-line server.js into 8 modules and create a structure that holds settings per guild. It's a major refactoring." It sounded intimidating, but since the program was already working and the logic was clear, I expected it might actually be finished fairly easily, as there were no unknown variables. I felt like this was exactly the kind of work AI excels at.
In fact, the code refactoring was finished in one day.
What Was Difficult Was Outside the Code
There was much more to think about regarding the work required to "make it a product" than there was for the code refactoring itself.
Legal
If you are going to charge money via subscriptions, you need to provide information based on the Act on Specified Commercial Transactions. You also have to write terms of service. Disclaimer clauses compliant with the Consumer Contract Act, refund policies, and the handling of personal information are unavoidable parts of selling a service as an individual developer.
I went through these one by one with the help of AI as well. By discussing things like, "What should I write for the Specified Commercial Transactions Act?" and "Do I need this clause?", I was finally able to create terms of service with 17 articles in total. Since I am not a legal expert, I cannot guarantee accuracy, but at least I escaped the state of having "thought about nothing."
Stripe Review
I use Stripe for payments, but to run it in a production environment, it needs to pass a Stripe review. They also check whether security is properly implemented.
So, I had the AI conduct a security audit of the entire project. 13 issues were pointed out. Missing JWT expiration checks, OAuth2 open redirect vulnerabilities, duplicate notifications for auction endings, and a lack of API rate limiting—I had the AI fix everything on the spot, including issues I hadn't even noticed myself.
Areas I had ignored for five years because "only I was using it" surfaced all at once during the productization phase.
Deployment
For production deployment of the Bot, I use my own home server. As I wrote in a previous article, I use a style where the AI accesses the server directly via SSH. Once I run deploy.sh, everything from the build to the container update is finished.
The web management dashboard is deployed on Vercel. For that, it is just a git push.
AuctionBOT
A bot that has only been running for my own guild for five years has been released as a service today.
AuctionBOT — Fully automated guild auction management via Discord.
-
/setupto automatically create channels,/auctionto start an auction - Members register to participate via reactions and bid by posting numbers
- After finishing, it automatically calculates the winning bid divided by the number of participants and notifies of the distribution results
- Anti-snipe (automatic extension for bids made just before the end)
- Supports 4 languages (English, Japanese, Korean, and Chinese)
- Free (1 concurrent auction) / Pro (500 yen/month, unlimited)
If there are guilds struggling with boss drop distributions or guild leaders tired of manual aggregation, please give it a try.
Conclusion
To be honest, the era has arrived where code refactoring is finished once you leave it to AI. Multi-tenancy, payment integration, and multilingual support—tasks with fixed patterns can be cleared away in one go.
However, "making it a product" does not end with just the code. Law, security, pricing, and landing pages—there are heaps of things you must decide yourself. AI can be a consultant, but you are the one who makes the final decision.
A tool that only I have used for five years can now be used by someone else starting today. I don't know if it will sell, but well, nothing starts unless you put it out there.
