What is Base62 encoding?

Base62 encoding is a binary-to-text encoding scheme that uses a 62-character alphabet consisting of digits 0-9 (10 characters), uppercase letters A-Z (26 characters), and lowercase letters a-z (26 characters). Unlike Base36 which is case-insensitive, Base62 is case-sensitive, allowing it to represent more data in fewer characters. It is commonly used by URL shorteners like bit.ly and YouTube for video IDs, and various systems that need compact, alphanumeric identifiers. Base62 uses only URL-safe characters without special symbols, making it perfect for creating short, memorable links and identifiers that can be easily typed, shared, and embedded in URLs without encoding issues.

What is the overhead of Base62 encoding?

Base62 encoding has approximately 35% overhead, meaning encoded data is about 35% larger than the original binary data. This is more efficient than Base32 (60% overhead), Base36 (50% overhead), and slightly more efficient than Base58 (37% overhead). It is close to Base64's 33% overhead but uses only alphanumeric characters, making it URL-safe without special characters like plus signs or slashes. For example, if you encode 100 bytes of binary data, the resulting Base62 string will be approximately 135 characters. This makes Base62 an excellent middle ground between compactness and simplicity—compact enough for short URLs but simple enough to type manually without confusion from special characters.

Is Base62 encoding case-sensitive?

Yes! Base62 encoding is case-sensitive. It distinguishes between uppercase and lowercase letters, treating "A" and "a" as different characters. This case sensitivity is what allows Base62 to use 62 characters instead of 36 (which would be case-insensitive like Base36). When decoding Base62 strings, you must preserve the exact case of each character, or the decoding will produce incorrect results. For example, "Hello" encodes to a different Base62 string than "hello". This case sensitivity is both a strength (more compact encoding) and a potential pitfall (case typos cause decoding errors). Always copy Base62 strings exactly, preserving uppercase and lowercase letters.

Should I use Base62 or Base64?

Choose Base62 when you need URL-safe encoding without special characters. Base62 uses only alphanumeric characters (0-9, A-Z, a-z), making it ideal for URLs, filenames, and identifiers that might be manually typed or displayed. Choose Base64 when efficiency is more important and you can handle special characters like plus signs, slashes, and equals signs. Base64 is slightly more compact (33% overhead vs 35%) and is standardized for email attachments and data URIs. Use Base62 for URL shorteners, database IDs, session tokens, and anywhere humans might read or type the encoded value. Use Base64 for API responses, image embedding, file attachments, and anywhere compactness matters more than manual typing.

Why do URL shorteners use Base62?

URL shorteners use Base62 because it maximizes the number of unique IDs in the shortest possible string using only URL-safe alphanumeric characters. By using 62 characters instead of 36 (Base36) or 10 (decimal), shorteners can create billions of unique short URLs with just 6-7 characters. For example, 6 Base62 characters can represent over 56 billion unique values (62^6), compared to only 2 billion with Base36 (36^6). The case-sensitivity and lack of special characters make Base62 perfect for memorable, typeable short URLs. Services like bit.ly, YouTube, and Twitter use Base62 to convert numeric IDs into compact strings like "dQw4w9WgXcQ" that fit easily in tweets, messages, and printed materials.

What character order does Base62 use?

The standard Base62 alphabet order is: digits first (0-9), then uppercase letters (A-Z), then lowercase letters (a-z). This gives the sequence: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz. This ordering is consistent across most implementations, though some systems may use different orders like alphabetical sorting or lowercase-first. When encoding and decoding, both sides must use the exact same alphabet order and agree on whether it is case-sensitive. This tool uses the standard digit-uppercase-lowercase order. If decoding fails, verify the alphabet order matches what was used during encoding.

Can I encode files with Base62?

Yes, Base62 can encode any file type including images, PDFs, documents, and executables. The file is converted to binary data, then encoded to a Base62 string. However, Base62 produces 35% larger output and is less efficient for large files compared to Base64. For file transmission, Base64 is usually preferred due to better compression and widespread support in email and HTTP. Base62 is better suited for encoding small pieces of data like file hashes, unique identifiers, or tokens that need to be URL-safe and easy to type. For example, encoding a file's SHA-256 hash (32 bytes) to Base62 produces a compact 43-character identifier perfect for file tracking systems or database keys.

Why does my Base62 string fail to decode?

Common Base62 decoding errors occur when: the string contains invalid characters (anything other than 0-9, A-Z, a-z); the case is incorrect (Base62 is case-sensitive, so "A" is not "a"); or the string was encoded with a different Base62 alphabet order. Ensure your string contains only valid Base62 characters, preserve the exact case from the original encoding, and verify that both encoding and decoding use the same alphabet order. Spaces and line breaks are typically ignored during decoding. If you receive a Base62 string from another system, confirm they use the standard 0-9A-Za-z alphabet order. Even a single case mismatch will corrupt the entire decoded output.

What is the difference between Base62 and Base58?

Base58 uses 58 characters and excludes visually similar characters (0, O, I, l) to prevent confusion when manually transcribing codes, while Base62 uses all 62 alphanumeric characters for slightly better efficiency. Base58 is popular in cryptocurrency (Bitcoin addresses, IPFS hashes) where humans need to read and type values without mistakes. Base62 is common in URL shorteners where case sensitivity is acceptable and maximum compactness is desired. Base62 produces slightly shorter output (35% overhead vs 37%) but requires careful attention to case and includes confusable characters like "0" vs "O". Choose Base58 for hand-typed crypto addresses; choose Base62 for copy-paste URL shortening and identifiers where efficiency matters more than transcription safety.

Is Base62 encoding secure or encrypted?

No! Base62 encoding is not encryption or a security measure. It is simply a way to represent binary data using alphanumeric characters. Base62-encoded data can be easily decoded by anyone with access to the string—it provides absolutely no confidentiality or protection. For security, you must encrypt data first using proper encryption algorithms like AES-256 or RSA, then optionally encode the encrypted bytes with Base62 for transmission or storage. Base62 is about representation and compatibility, not security. Never use Base62 alone to hide sensitive information like passwords or API keys. URL shorteners using Base62 rely on the unpredictability of random IDs, not on the encoding itself, for obscurity.

Free Base62 Encoder Online

Encode text to Base62 format instantly. Perfect for URL shorteners, compact identifiers, and short URLs. Case-sensitive 62-character alphabet. 100% free, secure, and works in your browser.

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