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B-SIDE

A daily CTF challenge with a fun new puzzle every day

What is B-SIDE?

This side program features challenges with a different flavor from Daily AlpacaHack. We publish one harder or more unconventional challenge every few days.

Join Anytime

Solve each challenge within its time window to appear on the leaderboard.

Not a Competition

Discussion with friends or AI is welcome (account sharing is prohibited).

Solution Sharing Rules

Sharing solutions is allowed only after the challenge period has ended.

New to CTFs?

This program features higher difficulty and unconventional challenges. Try the beginner-friendly Daily AlpacaHack first to warm up.

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Today's Challenge
arkark
nodebox
Misc
Very Very Hard
2 solves
Submissions (latest 3)
syn9

SOLVED!

Jul 26, 3:45 AM

nakamulab

SOLVED!

Jul 26, 12:55 AM

Leaderboard
Upcoming challenges reveal the , , and in advance.
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Jun 2026

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Upcoming
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1-5
minaminaominaminao
vanished
Misc
Very Hard
30 solves
6-9
tchentchen
YAuth
Misc
Hard
24 solves
 
tchentchen
YAuth
Misc
Hard
24 solves
10-15
ptr-yudaiptr-yudai
Gloinks
Misc
Very Very Hard
20 solves
 
ptr-yudaiptr-yudai
Gloinks
Misc
Very Very Hard
20 solves
16-20
tchentchen
InstaTalk
Web
Very Hard
23 solves
21-25
minaminaominaminao
Complete RSA
Crypto
Hard
25 solves
 
minaminaominaminao
Complete RSA
Crypto
Hard
25 solves
26-30
tan90909090tan90909090
New Directory
Misc
Hard
25 solves
 
tan90909090tan90909090
New Directory
Misc
Hard
25 solves
1-5
minaminaominaminao
missing ✌️
Crypto
Hard
31 solves

Writeups

Writeup for Long Flag Printer 2026

baumroll1234

ja
Long Flag Printer 2026

2026/07/22 03:07

Writeup for kappa maki

author
ja

2026/07/21 07:31

ojun

Writeup for kappa maki

ja

2026/07/18 09:11

kirehash

Writeup for invisible-grep

ja

2026/07/14 13:25

tchen

Writeup for InstaTalk

author
en

2026/07/06 07:37

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