ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character string format that combines a timestamp with random data to create identifiers that are both unique and sortable by creation time. ULIDs are an alternative to UUIDs with better sorting capabilities.

Why use ULIDs instead of UUIDs?

ULIDs offer several advantages over UUIDs: they are lexicographically sortable by generation time, they use a more compact representation (26 characters vs 36 for UUIDs), they're case-insensitive, and they avoid problematic characters like hyphens.

How do I convert a UUID to a ULID?

You can convert a UUID to a ULID using our UUID Converter tool. Simply paste your UUID into the input field and click Convert. The tool supports UUID v1, v4, v7, and any hex string, converting them losslessly to ULID format and back.

Can I decode a ULID to see its timestamp?

Yes, you can decode a ULID using our ULID Decoder tool. It will show you the timestamp in various formats (Unix timestamp, ISO string, human-readable date) and the random component in different representations.

Are ULIDs suitable for database primary keys?

Yes, ULIDs are excellent for database primary keys. They're sortable by creation time which improves database performance, they're URL-safe, and they can be generated without a central coordinator, making them ideal for distributed systems.

What is NanoID and when should I use it?

NanoID is a tiny, secure, URL-friendly unique string ID generator. It's smaller and faster than UUID and is ideal for generating short unique IDs for URLs, session tokens, or any situation where a compact random identifier is needed. Unlike ULID, NanoID is not time-sortable.

What is a Snowflake ID?

Snowflake ID is a 64-bit unique identifier format originally developed by Twitter. It encodes a timestamp, datacenter ID, machine ID, and sequence number. Snowflake IDs are sortable by time, extremely fast to generate, and widely used in distributed systems like Twitter, Discord, and Instagram.

How do I decode a JWT token?

Paste your JWT token into our JWT Decoder tool to instantly see the decoded header, payload, and signature. The tool shows all claims including expiry time (exp), issued-at (iat), and custom claims. No data is sent to any server — decoding is done entirely in your browser.

What is CUID and CUID2?

CUID (Collision-resistant Unique Identifier) is designed for horizontal scalability and sequential IDs for databases and distributed systems. CUID2 is the improved next generation with better security and randomness properties. Both are excellent alternatives to UUID for Node.js applications.

ULID Generator

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Tools Menu

ULID Decoder

Decode any ULID to reveal its embedded timestamp and random bits. Instantly see the exact creation time (UTC & local), Unix timestamp in milliseconds, and the 80-bit randomness component.

Decode ULID

Extract timestamp and randomness from ULID

ULID

Embedded Metadata Decoder

OFF

Metadata extraction is OFF

Enable to extract structured user-defined fields from the 80-bit randomness segment of the ULID.

ULID Visual Anatomy

01ARZ3NDEK TSV4RRFFQ69G5FAV

Timestamp Part (10 chars)

Represents 48 bits of Unix milliseconds. Encoded using Crockford's Base32. Gives ULIDs their natural chronological ordering.

Randomness Part (16 chars)

Represents 80 bits of cryptographically secure pseudorandomness (or monotonic progression). Prevents collisions.

Timestamp

Unix (ms):

ISO:

Local:

Randomness

Hex:

Base32:

Bits:

Validation Results

Format Check:

Timestamp Range:

Monotonicity Check:

ULID Structure Explained

01ARZ3NDEK

48-bit timestamp

7YF53YGHJ9EMZP8

80-bit randomness

Timestamp (10 chars): Milliseconds since Unix epoch — sortable and unique per millisecond
Randomness (16 chars): 80 bits of cryptographic randomness from crypto.getRandomValues()
Encoding: Crockford's Base32 — case-insensitive, excludes I, L, O, U to avoid ambiguity
Total: 26 characters, 128 bits — same entropy as UUID v4

Why Decode a ULID?

Audit when a database record was created from just its primary key
Debug distributed systems by correlating IDs across services
Verify monotonic ordering in high-throughput scenarios
Extract creation timestamps without a separate created_at column

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