Korea's largest algorithm training platform, Baekjoon Online Judge (BOJ), will shut down on April 28, 2026, after 16 years of operation.
What Was Baekjoon?
If LeetCode is the default for US developers, Baekjoon (acmicpc.net) was THE default for Korean developers. Founded in March 2010 by Baekjun Choi, a Sogang University CS student, it grew into the backbone of Korea's programming education ecosystem.
The scale is staggering:
| Metric | Number |
|---|---|
| Registered users | 634,000+ |
| Total submissions | 103,000,000+ |
| Problems | 34,500+ |
| Supported languages | 73 |
| Problems solved | 31,900+ (92%) |
Yes, you read that right — 73 languages, including Brainfuck and Aheui (a Korean esoteric programming language). The platform wasn't just a coding test prep tool; it was a celebration of programming culture.
The One-Person Operation
Here's the most remarkable part: one person ran this for 16 years. Baekjun Choi single-handedly maintained servers, curated problems, managed the judging system, and kept everything running for 634K users.
"I spent most of my 20s and 30s with this site," he wrote in his farewell announcement. "It was a small dream of mine to someday see users who joined as elementary school students bring their own children to use this platform."
Why Is It Shutting Down?
The official announcement is vague: "Due to various changes in circumstances." The community speculates:
- Sustainability — One person can only carry 634K users for so long
- Revenue model — BOJ was essentially free; commercial platforms took over enterprise coding tests
- Market shift — Companies moved to Programmers, HackerRank for hiring assessments
Data Preservation
- ✅ Problems, submissions, and contest data will be preserved
- ❌ Everything else will be deleted
- 🔄 Possibility of problems returning in a read-only format
- 💡 Founder is open to resuming service "if circumstances change"
What Made BOJ Special
solved.ac: A third-party difficulty rating system by Suhyeon Park that became integral to the BOJ experience — like a difficulty tier system for every problem.
Korean language support: 34,500+ problems available in Korean, making algorithm education accessible to students who weren't comfortable with English.
Unique culture: "Guddegi Cup" (a meme-problem contest), creative problem statements with humor, and a community that turned competitive programming into a cultural experience.
Alternatives
| Platform | Best For | Korean Support |
|---|---|---|
| Programmers | Enterprise coding tests | Full |
| LeetCode | Interview prep | Partial |
| Codeforces | Competitive programming | None |
| CodeTree | Structured learning | Full |
| AtCoder | Quality contest problems | Partial |
The Bigger Picture
BOJ's shutdown raises an important question: Should critical educational infrastructure depend on individual heroism?
634,000 users. 103 million submissions. One person. That's both a testament to what one dedicated developer can build — and a warning about sustainability in the open educational ecosystem.
If there are 12 days left, and you've never tried a Korean algorithm problem, now's your chance: acmicpc.net
Thank you, Baekjoon. One person's dedication raised an entire generation of Korean developers.
Source: Official shutdown announcement
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