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Daily AlpacaHack

A daily CTF challenge with a fun new puzzle every day

What is Daily AlpacaHack?

We publish one simple, beginner-friendly or educational CTF challenge every day!

Join Anytime

Solve within 24 hours of release to appear on the leaderboard.

Not a Competition

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

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Sharing solutions is allowed only after 24 hours have passed since release.

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Today's Challenge
k0080k0080
what-is-my-size
Pwn
Hard
20 solves
Submissions (latest 3)
toto1010orange

SOLVED!

Jun 20, 5:37 PM

Leaderboard

Try the first challenge

Is this your first CTF? Let's begin by tackling the first challenge released on Daily AlpacaHack.

View challenge
admin
AlpacaHack 2100
Misc
Welcome🌱
1,901 solves
Upcoming challenges reveal the , , and in advance.
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Jun 2026

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Upcoming
Mon
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1
admin
Half-Year Recap
Misc
Welcome🌱
228 solves
2
minaminaominaminao
Cache Me If You Can
Web
Easy🌱
191 solves
3
minaminaominaminao
vm1
Misc
Medium
93 solves
4
pppp4649pppp4649
Small e
Crypto
Easy🌱
131 solves
5
minaminaominaminao
RPS GAME
Misc
Crypto
Medium
96 solves
6
nozokare
Flag for localhost
Web
Easy🌱
151 solves
7
tan90909090tan90909090
C++ flag checker
Rev
Hard
83 solves
8
shiragishiragi
Guess IP
Misc
Easy🌱
137 solves
9
nozokare
A Piece of DHKE
Crypto
Medium
81 solves
10
shiragishiragi
chmod-swapper
Misc
Medium
81 solves
11
tchentchen
Alpaca Certification
Web
Easy🌱
147 solves
12
rsk0315
Floating Equality
Misc
Medium
89 solves
13
pppp4649pppp4649
Elliptic Equation
Crypto
Hard
57 solves
14
tchentchen
CAuth
Web
Hard
62 solves
15
minaminaominaminao
SITE/2
Web
Easy🌱
114 solves
16
tan90909090tan90909090
Xored PNG
Misc
Medium
84 solves
17
tchentchen
Looks like Alpacahack
Web
Medium
79 solves
18
shiragishiragi
Catrunner 2
Misc
Easy🌱
96 solves
19
minaminaominaminao
Flag Printer 20XX
Misc
Medium
59 solves
20
nozokare
xorshift521
Crypto
Hard
52 solves
21
k0080k0080
what-is-my-size
Pwn
Hard
20 solves
22
minaminaominaminao
Planned topicSecret Sharing
Crypto
Easy🌱
23
Planned topicNginx
Web
Medium
24
Planned topicBlock Cipher
Crypto
Medium
26
Coming soon
28
Planned topicTBA
Pwn
Hard
29
Coming soon
30
Coming soon
2
Planned topicMathematics
Crypto
Easy🌱
3
Coming soon
4
Coming soon
5
Coming soon

Want a harder challenge?

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Writeups

Daily AlpacaHackに挑戦するつくよみちゃん 06/20/xorshift521/nozokare

tsukuyomi-chan

ja
xorshift521

4 hours ago

Daily AlpacaHackに挑戦するつくよみちゃん 06/19/Flag Printer 20XX/minaminao

nirvana

Writeup for Catrunner 2

ja

2026/06/19 08:56

Daily AlpacaHackに挑戦するつくよみちゃん 06/18/Catrunner 2/shiragi

ja

2026/06/18 15:02

nirvana

Writeup for Looks like Alpacahack

Daily AlpacaHackに挑戦するつくよみちゃん 06/17/Looks like Alpacahack/tchen

Rows:

Half-Year Recap

Topic: WelcomeReleased: Jun 1, 2026

228 solves
Misc
Welcome🌱

by

admin

It has been half a year since Daily AlpacaHack started!

The stats for the first half-year:

  • Published challenges: 182
  • Submitted flags: 44,846
  • Correct flags: 34,818
  • Players who solved at least one challenge: 2,572
  • Writeups: 615
  • Challenge authors: 36
  • Players who solved every challenge: 24 ... 🦙 < wow!

The flag is Alpaca{thx_for_6_months_lets_build_next_gen_ctf_in_ai_era_see_u_tmr}

Please sign in to submit the flag.

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