A comprehensive comparison of all ID types supported by idt.
Type Bits Sortable Timestamp Random Bits String Length
UUIDv1 128 No Yes ~14 36 UUIDv3 128 No No 0 36 UUIDv4 128 No No 122 36 UUIDv5 128 No No 0 36 UUIDv6 128 Yes Yes ~62 36 UUIDv7 128 Yes Yes 62 36 ULID 128 Yes Yes 80 26 NanoID ~126 No No ~126 21 Snowflake 64 Yes Yes 0 ~19 KSUID 160 Yes Yes 128 27 ObjectId 96 Partial Yes ~40 24 XID 96 Yes Yes ~40 20 TSID 64 Yes Yes ~22 13-17
Type Precision Epoch
UUIDv1 100 nanoseconds October 15, 1582 UUIDv6 100 nanoseconds October 15, 1582 UUIDv7 Milliseconds Unix epoch (1970) ULID Milliseconds Unix epoch (1970) Snowflake Milliseconds Custom (e.g., 2010, 2015) KSUID Seconds May 13, 2014 ObjectId Seconds Unix epoch (1970) XID Seconds Unix epoch (1970) TSID Milliseconds Unix epoch (1970)
Type Same Millisecond Different Nodes Notes
UUIDv4 Excellent Excellent 122 random bits UUIDv7 Good Excellent 62 random bits + timestamp ULID Excellent Excellent Monotonic + 80 random bits NanoID Excellent Excellent ~126 random bits Snowflake Limited Requires coordination 4096/ms per worker
Type Encoding Case Sensitive Alphabet
UUID Hexadecimal No 0-9, a-f ULID Crockford Base32 No 0-9, A-Z (excluding I, L, O, U) NanoID Custom (default URL-safe) Yes A-Z, a-z, 0-9, -, _ Snowflake Decimal N/A 0-9 KSUID Base62 Yes 0-9, A-Z, a-z ObjectId Hexadecimal No 0-9, a-f XID Base32 No 0-9, a-v
Requirement Recommended Type
UUID compatibility required UUIDv7 Compact storage ULID or Snowflake Time-sortable queries UUIDv7, ULID, or Snowflake Maximum randomness UUIDv4 64-bit integer column Snowflake or TSID
Requirement Recommended Type
No coordination needed UUIDv7, ULID, UUIDv4 Very high throughput Snowflake Cross-datacenter UUIDv7 or ULID Compact wire format Snowflake (64-bit)
Requirement Recommended Type
Short URL slugs NanoID (custom length) Readable codes NanoID (custom alphabet) Compact but sortable ULID Standard format UUID (canonical)
Requirement Recommended Type
Non-sequential UUIDv4 or NanoID Hide creation time UUIDv4 or NanoID Cryptographic randomness UUIDv4 or NanoID
Since ULID and UUID are both 128-bit, they can be converted between each other:
# ULID to UUID hex
idt convert 01ARZ3NDEKTSV4RRFFQ69G5FAV -f hex
# Can be stored in UUID column
# UUID to various formats
idt convert 550e8400-e29b-41d4-a716-446655440000 -f base64
Type Binary (bytes) String (chars) Typical DB Type
UUID 16 36 UUID, CHAR(36), BINARY(16) ULID 16 26 CHAR(26), BINARY(16) NanoID ~16 21 VARCHAR(21+) Snowflake 8 ~19 BIGINT ObjectId 12 24 ObjectId, CHAR(24)
Feature UUIDv4 UUIDv7 ULID NanoID Snowflake
Time-sortable - Yes Yes - Yes Extract timestamp - Yes Yes - Yes URL-safe - - Yes Yes Yes Fits in 64-bit - - - - Yes No coordination Yes Yes Yes Yes - Customizable - - - Yes Yes RFC standard Yes Yes - - - Widely supported Yes Growing Growing Growing Yes