CLID - Clean ID Formats

A collection of clean, human-readable identifier formats without unnecessary complexity.

Format Specifications

CLID-1

<4 char>-<4 char>-<4 char>-<4 char>-<4 char>-<4 char>

• Total length: 24 characters (excluding hyphens)
• Hyphens included for readability
• Character set: A-Z, a-z, 0-9 (case sensitive)
• Example: AbC1-dEfG-89Hi-JkL0-mNoP-QrS2
• 0.0048% collision probability on 31,622,776,601,683,790,000 generated ID's.

CLID-1-TS

<timestamp>-<4 char>-<4 char>-<4 char>-<4 char>-<4 char>

• Timestamp (Base62 encoded) + 20 random characters
• Total length: timestamp length varies + 20 chars (excluding hyphens)
• Example: aB3xY-7kLm-NpQ9-RsTu-VwX0-YzA1

CLID-2

<4 char><4 char><4 char><4 char><4 char><4 char>

• Total length: 24 characters (no separators)
• Character set: A-Z, a-z, 0-9 (case sensitive)
• Example: AbC1dEfG89HiJkL0mNoPQrS2
• 0.0048% collision probability on 31,622,776,601,683,790,000 generated ID's.

CLID-2-TS

<timestamp><4 char><4 char><4 char><4 char><4 char>

• Timestamp (Base62 encoded) + 20 random characters
• Total length: timestamp length varies + 20 chars (no separators)
• Example: aB3xY7kLmNpQ9RsTuVwX0YzA1

CLID-3

21 characters using Base62 encoding (A-Z, a-z, 0-9)

• Example: aB3xY7kLmNpQ9RsTuVwX0

CLID-3-TS

<timestamp> + 15 random characters (Base62)

• Total length: timestamp length varies + 15 chars
• Example: xY9kLmNpQ9RsTuVwX0

CLID-4

20 characters using Base62 encoding

• Example: aB3xY7kLmNpQ9RsTuVw

CLID-4-TS

<timestamp> + 14 random characters (Base62)

• Total length: timestamp length varies + 14 chars
• Example: xY9kLmNpQ9RsTuVw

CLID-5

16 characters using Base62 encoding

• Example: aB3xY7kLmNpQ9RsT

CLID-5-TS

<timestamp> + 10 random characters (Base62)

• Total length: timestamp length varies + 10 chars
• Example: xY9kLmNpQ9R

Summary Table

Format	Separators	Total Char Length	Timestamp Support
CLID-1	Yes (hyphen)	24 (excl. hyphens)	Optional (TS variant)
CLID-2	No	24	Optional (TS variant)
CLID-3	No	21	Optional (TS variant)
CLID-4	No	20	Optional (TS variant)
CLID-5	No	16	Optional (TS variant)

Character Set

All CLID formats use Base62 character set:

• Uppercase: A-Z (26 chars)
• Lowercase: a-z (26 chars)
• Numbers: 0-9 (10 chars)

Total: 62 possible characters per position

Timestamp Encoding

When Timestamp (TS) variants are used:

• Current Unix timestamp is encoded to Base62
• Encoded length is typically 6 characters
• Timestamp always appears at the beginning of the ID

Collision Probability

All formats use Base62 (62 possible characters per position).

Format	Keyspace	Safe up to (1% risk)	50% collision at
CLID-1/2	~10^43	~4.6 × 10^20 IDs	~2.7 × 10^21 IDs
CLID-3	~10^37	~9.3 × 10^17 IDs	~1.7 × 10^18 IDs
CLID-4	~10^35	~3.7 × 10^17 IDs	~7.0 × 10^17 IDs
CLID-5	~10^28	~3.1 × 10^13 IDs	~5.8 × 10^14 IDs
CLID-1-TS/2-TS	~10^35 (random part)	~3.7 × 10^17 per second	~7.0 × 10^17/s
CLID-3-TS	~10^26 (random part)	~2.9 × 10^13 per second	~5.5 × 10^13/s
CLID-4-TS	~10^25 (random part)	~1.6 × 10^12 per second	~2.9 × 10^12/s
CLID-5-TS	~10^17 (random part)	~4.1 × 10^7 per second	~7.6 × 10^8/s

Collision probability is calculated using the birthday paradox approximation: P ≈ n² / 2N, where n = IDs generated and N = total keyspace.

Note on TS variants: The timestamp prefix is shared by all IDs generated within the same second, so collision resistance depends only on the random suffix. CLID-5-TS in particular is limited to ~41 million safe IDs per second — fine for most use cases, but worth knowing at high throughput.

Usage Notes

• All formats are case sensitive
• No external dependencies or third-party recommendations
• Simple, self-contained specification
• Compatible with any programming language that supports Base62 encoding

License

This specification is free to use and implement.