fatcousin
search
⌘
K
→
jump to any tool — keyboard-first launcher.
tools
→
browse every utility in one place.
manifesto
→
why fatcousin exists — local-first, no uploads.
install
→
save this toolset to your device — works offline.
search
⌘
K
→
jump to any tool — keyboard-first launcher.
←
home
i
s
b
n
v
a
l
i
d
a
t
o
r
validate isbn-10 and isbn-13 · check digit calc · convert between formats · runs locally
[
input
]
978-3-16-148410-0
0-306-40615-2
9780306406157
[
result
]
✓ valid
isbn-13
check digit
0
isbn-10
3-16-148410-X
copy
isbn-13
978-3-16-148410-0
copy
[
calculate check digit
]
check digit
7
[
status
]
>
ready
ready
local
verify
→