Coding & Decoding

Practice coding and decoding: apply substitution rules to encode and decode letters, numbers, and symbols. Free reasoning practice with instant feedback.

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Using the code below, decode the message:

Select the decoded word:

Explanation

 
How It Works
Coding and decoding tests measure your ability to understand and apply substitution rules. You'll be given a key that maps letters or symbols, then asked to encode or decode words using that system.
The generator ships 17 cipher systems across four tiers: substitution (letter-to-number, number-to-letter, Atbash, Caesar shift, symbol substitution, vowel-consonant mapping, keyboard shift), transposition (reverse word, skip cipher, rail fence), polyalphabetic (variable shift, Vigenère, ROT13), and special encodings (Polybius square, phone keypad, binary). Combined ciphers at expert difficulty chain two methods.
All codes are generated locally in your browser. Your progress and answers are stored only on your device — we never collect personal data.
Frequently Asked Questions
You'll encounter letter-to-number codes (A=1, B=2), reverse alphabet (A=Z, B=Y), shifted alphabets (each letter replaced by one N positions away), and symbol substitutions. Harder levels combine multiple rules.
Government agencies, civil service, banks, military, intelligence services, and organizations requiring security clearance. These tests are common in IBPS, SSC, and other competitive exams in many countries.
First, understand the code rule by examining the key carefully. Apply the rule letter by letter. For complex codes, write down intermediate steps. Check your answer by encoding it back to verify.
Each code system is procedurally generated using random substitution rules. The system selects a cipher type (letter shift, number mapping, reverse alphabet, or symbol substitution), applies it consistently to create encoded words, and generates distractors that contain specific decoding errors. Harder levels combine multiple rules. This ensures every question is unique.
Commonly Used In
Coding & Decoding skills are frequently assessed in recruitment and professional development across a range of industries and roles. Practicing these question types will help you prepare for aptitude tests from providers like SHL, Korn Ferry, Cubiks, and Talent Q.
Intelligence TestsCryptographyGovernment Aptitude Tests
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