UUID & Hash Generator

Generates unique IDs such as UUID v4, UUID v7, ULID and nanoid, and computes MD5, SHA-1, SHA-256, SHA-384, SHA-512 and CRC32 hashes of text or files. Use it when you need IDs for test data or want to verify the checksum of a downloaded file.

How to use

1. On the "UUID" tab, choose the "Type" and "How many" (up to 1,000); the IDs appear under "Generated IDs". Press "Generate again" for new ones, then copy them or press "Save as .txt".
2. Paste an existing ID into "Analyse a UUID or ULID" to see its version and the time stored inside it.
3. On the "Hash" tab, choose "Text" or "File" and add the content; a value appears for each algorithm.
4. Paste the published value into "Expected checksum" to see which result it matches. Enter an "HMAC key" to also get HMAC-SHA values.

How it works

• UUID v4 has 122 random bits from the browser's secure random generator. UUID v7 starts with the current Unix time in milliseconds (RFC 9562), so IDs sort in the order they were made.
• Text is hashed as UTF-8 bytes exactly as typed, so a trailing line break changes the result. Files are read in 4 MB pieces; for files over 1 GB, SHA is skipped and only MD5 and CRC32 are computed.
• Everything is computed in this browser. Text and files are never uploaded or saved.

Questions and answers

What is the difference between UUID v4 and v7?

A v4 UUID is completely random and has no order. A v7 UUID starts with its creation time, so IDs sort by when they were made, which suits database keys where order matters.

Can two UUIDs be the same?

A v4 UUID has 122 random bits, which gives 2 to the power of 122 possible values. A repeat is possible in theory, but so unlikely that UUIDs are treated as unique in practice.

How do I verify the SHA-256 checksum of a downloaded file?

On the "Hash" tab choose "File" and drop the file, then paste the value from the download page into "Expected checksum". If it matches, the page names the algorithm it matches.

Is MD5 safe for storing passwords?

No. MD5 and SHA-1 are broken for security. Use them only to detect accidental changes to a file.