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🎁 Free Developer Encoding Cheatsheet

Base64, URL encoding, JSON, Hash types, Regex basics — all in one place. Print it or save as PDF.

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Developer Encoding Cheatsheet

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🔐Base64 Encoding
What it isWhen to useExample
Converts binary data to text using 64 characters (A-Z, a-z, 0-9, +, /)Embedding images in HTML/CSS, email attachments, API data transferHello → SGVsbG8=
RuleDetail
Output lengthAlways ~33% longer than input. Every 3 bytes → 4 Base64 chars
Padding= or == at end means padding was added to complete 4-char group
URL-safe variantReplace + with - and / with _ for use in URLs
NOT encryptionBase64 is encoding, not security — anyone can decode it instantly
🔗URL Encoding (Percent Encoding)
CharacterEncoded
Space%20
!%21
#%23
$%24
&%26
'%27
(%28
)%29
CharacterEncoded
*%2A
+%2B
,%2C
/%2F
:%3A
=%3D
?%3F
@%40
Safe characters (no encoding needed): A-Z a-z 0-9 - _ . ~
🛡️Hash Functions — Quick Reference
HashOutput LengthUse ForSecurity
MD532 hex chars (128-bit)File checksums, non-security useWeak — do not use for passwords
SHA-140 hex chars (160-bit)Legacy systems, Git commitsWeak — deprecated for security
SHA-25664 hex chars (256-bit)File verification, digital signaturesStrong — current standard
SHA-512128 hex chars (512-bit)High-security applicationsVery Strong
bcrypt60 charsPassword storage (with salt)Best for passwords
⚠️ Hashes are one-way. You cannot reverse a hash — only compare. Same input always gives same output.
📋JSON Rules & Common Errors
Valid JSON Data Types
String"hello world"
Number42 or 3.14
Booleantrue or false
Nullnull
Array[1, 2, 3]
Object{"key": "value"}
Common JSON Errors
Trailing comma{"a":1,} ← invalid
Single quotes{'key':'val'} ← invalid
Unquoted keys{key:"val"} ← invalid
Comments// comment ← not allowed
Undefinedundefined ← not a type
NaN/InfinityNot valid JSON values
🔎Regex Quick Reference
PatternMatches
.Any character except newline
\dAny digit (0-9)
\wWord char (a-z, A-Z, 0-9, _)
\sWhitespace (space, tab, newline)
^Start of string
$End of string
[abc]Any of: a, b, or c
[^abc]Not a, b, or c
QuantifierMeaning
*0 or more times
+1 or more times
?0 or 1 time (optional)
{3}Exactly 3 times
{2,5}Between 2 and 5 times
(abc)Capture group
a|ba or b
\bWord boundary
Common Regex PatternsPattern
Email address^[\w.-]+@[\w.-]+\.\w{2,}$
URLhttps?:\/\/(www\.)?[-a-zA-Z0-9@:%._+~#=]{2,256}\.[a-z]{2,6}
Phone (US)^\+?1?\s?\(?\d{3}\)?[\s.-]?\d{3}[\s.-]?\d{4}$
Strong password^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$
📡Morse Code — Letters & Numbers
LetterMorseLetterMorse
A.-N-.
B-...O---
C-.-.P.--.
D-..Q--.-
E.R.-.
F..-.S...
G--.T-
H....U..-
I..V...-
J.---W.--
K-.-X-..-
L.-..Y-.--
M--Z--..
NumberMorse
0-----
1.----
2..---
3...--
4....-
5.....
6-....
7--...
8---..
9----.
Word separator: 3 spaces. Letter separator: 1 space.
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Password Generatortheencodedbox.com/password-generator.html
ToolURL
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Word Countertheencodedbox.com/word-counter.html
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