ULID Generator — Free Online ULID Decoder & ULID to UUID Converter

ULID Generator — Free Online ULID Decoder & ULID to UUID Converter. Free online ULID generator. Create up to 500 sortable ULIDs (monotonic or lowercase), decode any ULID to its timestamp and convert ULID to UUID and back — 100% in your browser.

Our free online ULID generator creates Universally Unique Lexicographically Sortable Identifiers in bulk — from 1 up to 500 at a time — and lets you export them as plain lines, a JSON array or CSV.

Every ULID is 26 characters of Crockford base32: the first 10 characters encode a 48-bit millisecond timestamp and the last 16 carry 80 bits of cryptographically secure randomness, so IDs sort by creation time as plain strings.

Turn on monotonic mode to guarantee strictly increasing IDs even when many are generated in the same millisecond, or switch to lowercase output for case-sensitive systems. Copy the list, download it as a file, or share a link that restores your settings.

The built-in ULID decoder reads any ULID and extracts its ULID timestamp (Unix milliseconds, ISO 8601 UTC and your local time) along with the time and randomness components, and it validates the Crockford alphabet so typos are caught instantly.

Because a ULID and a UUID are both 128-bit values, the tool also works as a ULID converter: see the ULID to UUID form of every decoded ID, or paste a UUID to convert UUID to ULID — handy when a database column is typed uuid but you want sortable keys.

If you need classic random identifiers instead, use our UUID Generator; to turn raw timestamps into dates, try the Date-Time Converter.

ULID vs UUID: a random UUID v4 is unordered, which fragments B-tree indexes and makes "newest first" queries slower, while a ULID keeps inserts append-only and remains URL-safe, case-insensitive and shorter (26 vs 36 characters).

ULIDs are a great fit for primary keys in PostgreSQL, MySQL and DynamoDB, event IDs in Kafka streams, log correlation IDs and file names that must sort chronologically.

Every ID is generated locally in your browser with the Web Crypto API — nothing is sent to a server. Related tools: UUID Generator, Token Generator and Date-Time Converter.

Frequently asked questions

How do I generate ULIDs online?

Set Quantity (1 to 500) and choose a Format: Raw puts one ULID per line, JSON gives an array and CSV a comma-separated list. Click Refresh for new IDs, Copy to copy them or Download to save a .txt, .json or .csv file. Your quantity and options are remembered in this browser.

What is a ULID?

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit ID written as 26 Crockford base32 characters. The first 10 characters encode a millisecond timestamp and the last 16 are random, so ULIDs sort by creation time as plain text, unlike random UUID v4 values.

What does Monotonic mode do?

All IDs in one batch share the same timestamp. With Monotonic on, the random part is incremented for each ID, so the list is strictly increasing and stays in generation order when sorted. With it off, each ID gets fresh random bits and IDs from the same millisecond can sort in any order.

How do I get the timestamp from a ULID?

Paste it into ULID to decode, or click Decode first ULID. The table shows the Unix timestamp in milliseconds, the UTC date in ISO 8601, your local date, the time and random components and the equivalent UUID. Input with the wrong length or the letters I, L, O or U shows an error.

Can I convert a UUID to a ULID and back?

Yes. Both are 128-bit values, so the conversion is lossless. The decoder shows the UUID form of any ULID, and the UUID to ULID converter turns a UUID, with or without hyphens, into a ULID. A converted UUID v4 does not contain a meaningful timestamp.

Are the ULIDs generated securely and privately?

Yes. IDs are generated in your browser with the ulid library, which uses the Web Crypto random generator, and nothing is sent to a server.

How to use this online tool

ULID Generator — Free Online ULID Decoder & ULID to UUID Converter is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.

Private processing in your browser

ULID Generator — Free Online ULID Decoder & ULID to UUID Converter keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.

When this tool is useful

Use ULID Generator — Free Online ULID Decoder & ULID to UUID Converter for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.

Practical tips

Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.