Ulid compare

ulid-compare · version 1.0.0 · Identifiers & check digits · free, no key needed

Compare two canonical uppercase ULIDs by their specification-defined lexical order.

Use when you need to: compare canonical ULIDs · sort two ULID values · determine ULID lexical order.

Decide before calling

Read the versioned contract and the supported scope below. Reuse ulid-compare@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use ulid-compare@1.0.0 for compare canonical ULIDs. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• compare canonical ULIDs
• sort two ULID values
• determine ULID lexical order
• order ULIDs chronologically
• compare ULID strings strictly
• rank two canonical ULIDs

Not supported

• sort an unbounded ULID list
• normalize invalid ULIDs

Behavior

• Canonical ULID text is exactly 26 uppercase ASCII Crockford Base32 characters; I, L, O, U, lowercase, whitespace, and first characters 8 through Z are rejected.
• The 48-bit timestamp is represented as a canonical unsigned decimal string, avoiding JSON number precision loss.
• Inputs are never trimmed or normalized; operations are synchronous, pure, offline, bounded, and deterministic.

Input

• left (string, required): min length 26; max length 26; pattern ^[0-7][0-9A-HJKMNP-TV-Z]{25}$
• right (string, required): min length 26; max length 26; pattern ^[0-7][0-9A-HJKMNP-TV-Z]{25}$

Output

• order (integer, required): min -1; max 1

Limits

• max ulid bytes: 26
• max ulids: 2

Example

Request input:

{
  "left": "00000000000000000000000000",
  "right": "00000000000000000000000001"
}

Response:

{
  "result": {
    "order": -1
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "ulid-compare",
  "version": "1.0.0",
  "input": {
    "left": "00000000000000000000000000",
    "right": "00000000000000000000000001"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/ulid-compare/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"left":"00000000000000000000000000","right":"00000000000000000000000001"}'

The machine-readable contract is at /v1/tools/ulid-compare/versions/1.0.0.

CLI

node cli.mjs run ulid-compare 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Ulid parse canonical: Parse a canonical uppercase ULID into its exact timestamp, randomness, and 16 bytes.
• Ulid timestamp extract: Extract the exact unsigned 48-bit millisecond timestamp from a canonical uppercase ULID.
• Iban compute from bban: Compute the MOD 97-10 check digits and full IBAN for a country code and BBAN, using the pinned IBAN registry.
• Rf creditor reference compute: Compute the MOD 97-10 check digits and full ISO 11649 RF Creditor Reference for a base reference (invoice number).
• Ulid format: Format an explicit 48-bit timestamp and ten random bytes as one canonical uppercase ULID.
• Uuid inspect: Validate a canonical UUID and report its lowercase value, variant, version, and nil status.